PowerAuth Mobile SDK for Android
Installation
To get PowerAuth SDK for Android up and running in your app, add the following dependency in your gradle.build file:
repositories {
mavenCentral() // if not defined elsewhere...
}
dependencies {
compile 'com.wultra.android.powerauth:powerauth-sdk:1.x.y'
}
Note that this documentation is using version 1.x.y as an example. You can find the latest version in our List of Releases. The Android Studio IDE can also find and offer updates for your application’s dependencies.
From now on, you can use PowerAuthSDK class in your project.
To use development version, you need to install it in your local Maven repository and make this repository available to your Gradle script.
$ git clone --recurse-submodules https://github.com/wultra/powerauth-mobile-sdk.git
$ cd powerauth-mobile-sdk/proj-android
$ sh build-publish-local.sh
In your Gradle script:
apply plugin: "maven"
repositories {
mavenLocal()
}
You also need to install base Java modules in your maven repository:
$ git clone --recurse-submodules https://github.com/wultra/powerauth-restful-integration.git
$ cd powerauth-restful-integration
$ mvn clean install -DskipTests=true
Configuration
In order to be able to configure your PowerAuthSDK instance, you need the following values from the PowerAuth Server:
MOBILE_SDK_CONFIG- String that contains cryptographic configuration.
You also need to specify your instance ID (by default, this can be for example an app package name). This is because one application may use more than one custom instance of PowerAuthSDK, and the identifier is the way to distinguish these instances while working with Keychain data.
Finally, you need to know the location of your PowerAuth Standard RESTful API endpoints. That path should contain everything that goes before the /pa/** prefix of the API endpoints.
To sum it up, in order to configure the PowerAuthSDK default instance, add the following code to your application main activity onCreate() method:
val INSTANCE_ID = applicationContext.packageName
val MOBILE_SDK_CONFIG = "MTIzNDU2Nz...jc4OTAxMg=="
val API_SERVER = "https://localhost:8080/demo-server"
try {
val configuration = PowerAuthConfiguration.Builder(
INSTANCE_ID,
API_SERVER,
MOBILE_SDK_CONFIG)
.build()
val powerAuthSDK = PowerAuthSDK.Builder(configuration)
.build(applicationContext)
} catch (exception: PowerAuthErrorException) {
// Failed to construct `PowerAuthSDK` due to insufficient keychain protection.
// (See next chapter for details)
}
String INSTANCE_ID = getApplicationContext().getPackageName();
String MOBILE_SDK_CONFIG = "MTIzNDU2Nz...jc4OTAxMg==";
String API_SERVER = "https://localhost:8080/demo-server";
try {
final PowerAuthConfiguration configuration = new PowerAuthConfiguration.Builder(
INSTANCE_ID,
MOBILE_SDK_CONFIG)
.build();
PowerAuthSDK powerAuthSDK = new PowerAuthSDK.Builder(configuration)
.build(getApplicationContext());
} catch (PowerAuthErrorException e) {
// Failed to construct `PowerAuthSDK` due to insufficient keychain protection.
// (See next chapter for details)
}
If you don’t provide the application’s context to the build() method, then PowerAuthSDK will fail to register its components for the application’s lifecycle callbacks. To fix this, please use the following code in your application’s onCreate() method:
PowerAuthAppLifecycleListener.getInstance().registerForActivityLifecycleCallbacks(this) // "this" is Application
Additional configuration methods
The PowerAuthConfiguration.Builder class provides the following additional methods that can alter the configuration:
offlineSignatureComponentLength()- Alters the default component length for the offline signature. The values between 4 and 8 are allowed. The default value is 8.externalEncryptionKey()- See External Encryption Key chapter for more details.disableAutomaticProtocolUpgrade()- Disables the automatic protocol upgrade. This option should be used only for debugging purposes.
Activation Data Protection
By default, the PowerAuth Mobile SDK for Android encrypts the local activation data with a symmetric key generated by the Android KeyStore on Android 6 and newer devices. On older devices, or if the device has an unreliable KeyStore implementation, then the fallback to unencrypted storage, based on private SharedPreferences is used. If your application requires a higher level of activation data protection, then you can enforce the level of protection in PowerAuthKeychainConfiguration:
try {
val keychainConfig = PowerAuthKeychainConfiguration.Builder()
.minimalRequiredKeychainProtection(KeychainProtection.HARDWARE)
.build()
// Apply keychain configuration
val powerAuthSDK = PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(context)
} catch (e: PowerAuthErrorException) {
// Failed to construct `PowerAuthSDK` due to insufficient keychain protection.
}
try {
PowerAuthKeychainConfiguration keychainConfig = new PowerAuthKeychainConfiguration.Builder()
.minimalRequiredKeychainProtection(KeychainProtection.HARDWARE)
.build();
// Apply keychain configuration
PowerAuthSDK powerAuthSDK = new PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(getApplicationContext());
} catch (PowerAuthErrorException e) {
// Failed to construct `PowerAuthSDK` due to insufficient keychain protection.
}
You can also determine the level of keychain protection before PowerAuthSDK object creation by calling:
val keychainProtectionLevel = KeychainFactory.getKeychainProtectionSupportedOnDevice(context)
@KeychainProtection int keychainProtectionLevel = KeychainFactory.getKeychainProtectionSupportedOnDevice(context));
The following levels of keychain protection are defined:
-
NONE- The content of the keychain is not encrypted and therefore not protected. This level of protection is typically reported on devices older than Android Marshmallow, or in case the device has faulty KeyStore implementation. -
SOFTWARE- The content of the keychain is encrypted with a key generated by Android KeyStore, but the key is protected only on the operating system level. The security of the key material relies solely on software measures, which means that a compromise of the Android OS (such as a “root” exploit) might up revealing this key. -
HARDWARE- The content of the keychain is encrypted with a key generated by Android KeyStore and the key is stored and managed by Trusted Execution Environment. -
STRONGBOX- The content of the keychain is encrypted with a key generated by Android KeyStore and the key is stored inside of Secure Element (e.g. StrongBox). This is the highest level of Keychain protection currently available, but not enabled by default. See note below.
Be aware, that enforcing the required level of protection must be properly reflected in your application’s user interface. That means that you should inform the user in case the device has insufficient capabilities to run your application securely.
StrongBox Support Note
The StrongBox-backed keys are by default turned off due to poor reliability and low performance of StrongBox implementations on the current Android devices. If you want to turn support on in your application, then use the following code at your application’s startup:
try {
KeychainFactory.setStrongBoxEnabled(context, true)
} catch (e: PowerAuthErrorException) {
// You must alter the configuration before any keychain is accessed.
// Basically, you should not create any PowerAuthSDK instance before the change.
}
try {
KeychainFactory.setStrongBoxEnabled(context, true);
} catch (PowerAuthErrorException e) {
// You must alter the configuration before any keychain is accessed.
// Basically, you should not create any PowerAuthSDK instance before the change.
}
Activation
After you configure the SDK instance, you are ready to make your first activation.
Activation via Activation Code
The original activation method uses a one-time activation code generated in PowerAuth Server. To create an activation using this method, some external application (Internet banking, ATM application, branch / kiosk application) must generate an activation code for you and display it (as a text or in a QR code).
In case you would like to use QR code scanning to enter an activation code, you can use any library of your choice, for example Barcode Scanner open-source library based on ZBar lib.
Use the following code to create an activation once you have an activation code:
val deviceName = "Petr's Leagoo T5C"
val activationCode = "VVVVV-VVVVV-VVVVV-VTFVA" // let user type or QR-scan this value
// Create activation object with given activation code.
val activation: PowerAuthActivation
try {
activation = PowerAuthActivation.Builder.activation(activationCode, deviceName).build()
} catch (e: PowerAuthErrorException) {
// Invalid activation code
}
// Create a new activation with the given activation object
powerAuthSDK.createActivation(activation, object: ICreateActivationListener {
override fun onActivationCreateSucceed(result: CreateActivationResult) {
val fingerprint = result.activationFingerprint
val activationRecovery = result.recoveryData
// No error occurred, proceed to credentials entry (PIN prompt, Enable "Fingerprint Authentication" switch, ...) and persist
// The 'fingerprint' value represents the combination of device and server public keys - it may be used as visual confirmation
// If the server supports recovery codes for activation, then `activationRecovery` contains object with information about activation recovery.
}
override fun onActivationCreateFailed(t: Throwable) {
// Error occurred, report it to the user
}
})
String deviceName = "Petr's Leagoo T5C";
String activationCode = "VVVVV-VVVVV-VVVVV-VTFVA"; // let user type or QR-scan this value
// Create an activation object with the given activation code.
final PowerAuthActivation activation;
try {
activation = PowerAuthActivation.Builder.activation(activationCode, deviceName).build();
} catch (PowerAuthErrorException e) {
// Invalid activation code
}
// Create a new activation with the given activation object
powerAuthSDK.createActivation(activation, new ICreateActivationListener() {
@Override
public void onActivationCreateSucceed(CreateActivationResult result) {
final String fingerprint = result.getActivationFingerprint();
final RecoveryData activationRecovery = result.getRecoveryData();
// No error occurred, proceed to credentials entry (PIN prompt, Enable "Fingerprint Authentication" switch, ...) and persist
// The 'fingerprint' value represents the combination of device and server public keys - it may be used as visual confirmation
// If the server supports recovery codes for activation, then `activationRecovery` contains object with information about activation recovery.
}
@Override
public void onActivationCreateFailed(Throwable t) {
// Error occurred, report it to the user
}
});
If the received activation result also contains recovery data, then you should display those values to the user. To do that, please read the Getting Recovery Data section of this document, which describes how to treat that sensitive information. This is relevant for all types of activation you use.
Additional Activation OTP
If an additional activation OTP is required to complete the activation, then use the following code to configure the PowerAuthActivation object:
val deviceName = "Petr's iPhone 7" // or UIDevice.current.name
val activationCode = "VVVVV-VVVVV-VVVVV-VTFVA" // let user type or QR-scan this value
val activationOtp = "12345"
// Create an activation object with the given activation code and OTP.
val activation: PowerAuthActivation
try {
activation = PowerAuthActivation.Builder.activation(activationCode, deviceName)
.setAdditionalActivationOtp(activationOtp)
.build();
} catch (e: PowerAuthErrorException) {
// Invalid activation code
}
// The rest of the activation routine is the same.
String deviceName = "Petr's iPhone 7" // or UIDevice.current.name
String activationCode = "VVVVV-VVVVV-VVVVV-VTFVA" // let user type or QR-scan this value
String activationOtp = "12345"
// Create activation object with given activation code and OTP.
final PowerAuthActivation activation;
try {
activation = PowerAuthActivation.Builder.activation(activationCode, deviceName)
.setAdditionalActivationOtp(activationOtp)
.build();
} catch (PowerAuthErrorException e) {
// Invalid activation code
}
// The rest of the activation routine is the same.
Be aware that OTP can be used only if the activation is configured for ON_KEY_EXCHANGE validation on the PowerAuth server. See our crypto documentation for details.
Activation via Custom Credentials
You may also create an activation using any custom login data - it can be anything that the server can use to obtain the user ID to associate with a new activation. Since the credentials are custom, the server’s implementation must be able to process such a request. Unlike the previous versions of SDK, the custom activation no longer requires a custom activation endpoint.
Use the following code to create an activation using custom credentials:
// Create a new activation with a given device name and login credentials
val deviceName = "Juraj's JiaYu S3"
val credentials = mapOf("username" to "[email protected]", "password" to "YBzBEM")
// Create an activation object with the given credentials.
val activation: PowerAuthActivation
try {
activation = PowerAuthActivation.Builder.customActivation(credentials, deviceName).build()
} catch (e: PowerAuthErrorException) {
// Credentials dictionary is empty
}
// Create a new activation with the given activation object
powerAuthSDK.createActivation(activation, object: ICreateActivationListener {
override fun onActivationCreateSucceed(result: CreateActivationResult) {
val fingerprint = result.activationFingerprint
val activationRecovery = result.recoveryData
// No error occurred, proceed to credentials entry (PIN prompt, Enable "Biometric Authentication" switch, ...) and persist
// The 'fingerprint' value represents the combination of device and server public keys - it may be used as visual confirmation
// If the server supports recovery codes for activation, then `activationRecovery` contains object with information about activation recovery.
}
override fun onActivationCreateFailed(t: Throwable) {
// Error occurred, report it to the user
}
})
// Create a new activation with a given device name and login credentials
String deviceName = "Juraj's JiaYu S3";
Map<String, String> credentials = new HashMap<>();
credentials.put("username", "[email protected]");
credentials.put("password", "YBzBEM");
// Create an activation object with the given credentials.
final PowerAuthActivation activation;
try {
activation = PowerAuthActivation.Builder.customActivation(credentials, deviceName).build();
} catch (PowerAuthErrorException e) {
// Credentials dictionary is empty
}
// Create a new activation with the given activation object
powerAuthSDK.createActivation(activation, new ICreateActivationListener() {
@Override
public void onActivationCreateSucceed(CreateActivationResult result) {
final String fingerprint = result.getActivationFingerprint();
final RecoveryData activationRecovery = result.getRecoveryData();
// No error occurred, proceed to credentials entry (PIN prompt, Enable "Biometric Authentication" switch, ...) and persist
// The 'fingerprint' value represents the combination of device and server public keys - it may be used as visual confirmation
// If the server supports recovery codes for activation, then `activationRecovery` contains object with information about activation recovery.
}
@Override
public void onActivationCreateFailed(Throwable t) {
// Error occurred, report it to the user
}
});
Note that by using weak identity attributes to create an activation, the resulting activation confirms a “blurry identity”. This may greatly limit the legal weight and usability of a signature. We recommend using a strong identity verification before activation can actually be created.
Activation via Recovery Code
If the PowerAuth Server is configured to support Recovery Codes, then also you can create an activation via the recovery code and PUK.
Use the following code to create an activation using the recovery code:
val deviceName = "John Tramonta"
val recoveryCode = "55555-55555-55555-55YMA" // User's input
val puk = "0123456789" // User's input. You should validate RC & PUK with using ActivationCodeUtil
// Create an activation object with the given recovery code and PUK.
val activation: PowerAuthActivation
try {
activation = PowerAuthActivation.Builder.recoveryActivation(recoveryCode, puk, deviceName).build();
} catch (e: PowerAuthErrorException) {
// Invalid recovery code or PUK
}
// Create a new activation with the given activation object
powerAuthSDK.createActivation(activation, object: ICreateActivationListener {
override fun onActivationCreateSucceed(result: CreateActivationResult) {
val fingerprint = result.activationFingerprint
val activationRecovery = result.recoveryData
// No error occurred, proceed to credentials entry (PIN prompt, Enable "Biometric Authentication" switch, ...) and persist
// The 'fingerprint' value represents the combination of device and server public keys - it may be used as visual confirmation
// If the server supports recovery codes for activation, then `activationRecovery` contains object with information about activation recovery.
}
override fun onActivationCreateFailed(t: Throwable) {
// Error occurred, report it to the user
// On top of regular error processing, you should handle a special situation, when the server gives additional information
// about which PUK must be used for the recovery. The information is valid only when recovery code from a postcard is applied.
if (t is ErrorResponseApiException) {
val errorResponse = t.errorResponse
val currentRecoveryPukIndex = t.currentRecoveryPukIndex
if (currentRecoveryPukIndex > 0) {
// The PUK index is known, you should inform the user that it has to rewrite PUK from a specific position.
}
}
}
})
final String deviceName = "John Tramonta"
final String recoveryCode = "55555-55555-55555-55YMA" // User's input
final String puk = "0123456789" // User's input. You should validate RC & PUK with using ActivationCodeUtil
// Create an activation object with the given recovery code and PUK.
final PowerAuthActivation activation;
try {
activation = PowerAuthActivation.Builder.recoveryActivation(recoveryCode, puk, deviceName).build();
} catch (PowerAuthErrorException e) {
// Invalid recovery code or PUK
}
// Create a new activation with the given activation object
powerAuthSDK.createActivation(activation, new ICreateActivationListener() {
@Override
public void onActivationCreateSucceed(CreateActivationResult result) {
final String fingerprint = result.getActivationFingerprint();
final RecoveryData activationRecovery = result.getRecoveryData();
// No error occurred, proceed to credentials entry (PIN prompt, Enable "Biometric Authentication" switch, ...) and persist
// The 'fingerprint' value represents the combination of device and server public keys - it may be used as visual confirmation
// If the server supports recovery codes for activation, then `activationRecovery` contains object with information about activation recovery.
}
@Override
public void onActivationCreateFailed(Throwable t) {
// Error occurred, report it to the user
// On top of regular error processing, you should handle a special situation, when the server gives an additional information
// about which PUK must be used for the recovery. The information is valid only when a recovery code from a postcard is applied.
if (t instanceof ErrorResponseApiException) {
ErrorResponseApiException exception = (ErrorResponseApiException) t;
Error errorResponse = exception.getErrorResponse();
int currentRecoveryPukIndex = exception.getCurrentRecoveryPukIndex();
if (currentRecoveryPukIndex > 0) {
// The PUK index is known, you should inform the user that it has to rewrite PUK from a specific position.
}
}
}
});
Customize Activation
You can set additional properties to PowerAuthActivation object before any type of activation is created. For example:
val deviceName = "Petr's Leagoo T5C"
val activationCode = "VVVVV-VVVVV-VVVVV-VTFVA" // let user type or QR-scan this value
// Custom attributes that can be processed before the activation is created on PowerAuth Server.
// The dictionary may contain only values that can be serialized to JSON.
val otherIds = arrayOf(
"e43f5f99-e2e9-49f2-bcae-5e32a5e96d22",
"41dd704c-65e6-4d4b-b28f-0bc0e4eb9715"
)
val customAttributes = mapOf<String, Any>(
"isPrimaryActivation" to true,
"otherActivationIds" to otherIds
)
// Extra flags that will be associated with the activation record on PowerAuth Server.
val extraFlags = "EXTRA_FLAGS"
// Now create the activation object with all that extra data
val activation: PowerAuthActivation
try {
activation = PowerAuthActivation.Builder.activation(activationCode, deviceName)
.setCustomAttributes(customAttributes)
.setExtras(extraFlags)
.build();
} catch (e: PowerAuthErrorException) {
// Invalid activation code
}
// The rest of the activation routine is the same.
String deviceName = "Petr's Leagoo T5C";
String activationCode = "VVVVV-VVVVV-VVVVV-VTFVA"; // let user type or QR-scan this value
// Custom attributes that can be processed before the activation is created on PowerAuth Server.
// The dictionary may contain only values that can be serialized to JSON.
List<String> otherIds = new ArrayList<>();
otherIds.add("e43f5f99-e2e9-49f2-bcae-5e32a5e96d22");
otherIds.add("41dd704c-65e6-4d4b-b28f-0bc0e4eb9715");
Map<String, Object> customAttributes = new HashMap<>();
customAttributes.put("isPrimaryActivation", true);
customAttributes.put("otherActivationIds", otherIds);
// Extra flags that will be associated with the activation record on PowerAuth Server.
String extraFlags = "EXTRA_FLAGS"
// Now create the activation object with all that extra data
final PowerAuthActivation activation;
try {
activation = PowerAuthActivation.Builder.activation(activationCode, deviceName)
.setCustomAttributes(customAttributes)
.setExtras(extraFlags)
.build();
} catch (PowerAuthErrorException e) {
// Invalid activation code
}
// The rest of the activation routine is the same.
Persisting Activation Data
After you create an activation using one of the methods mentioned above, you need to persist the activation - to use provided user credentials to store the activation data on the device. Use the following code to do this.
// Persist activation using given PIN
val result = powerAuthSDK.persistActivationWithPassword(context, pin)
if (result != PowerAuthErrorCodes.SUCCEED) {
// happens only in case SDK was not configured or activation is not in the state to be persisted
}
// Persist activation using given PIN
int result = powerAuthSDK.persistActivationWithPassword(context, pin);
if (result != PowerAuthErrorCodes.SUCCEED) {
// happens only in case SDK was not configured or activation is not in the state to be persisted
}
This code has created activation with two factors: possession (key stored using a key derived from a device fingerprint) and knowledge (password, in our case, a simple PIN code). If you would like to enable biometric authentication support at this moment, use the following code instead of the one above:
// Persist activation using given PIN and ad-hoc generated biometric related key
powerAuthSDK.persistActivation(context, fragment, "Enable Biometric Authentication", "To enable biometric authentication, use the biometric sensor on your device.", pin, object: IPersistActivationWithBiometricsListener {
override fun onBiometricDialogCancelled() {
// Biometric enrolment cancelled by user
}
override fun onBiometricDialogSuccess() {
// success, activation has been persisted
}
override fun onBiometricDialogFailed(error: PowerAuthErrorException) {
// failure, typically as a result of API misuse, or a biometric authentication failure
}
})
// Persist activation using given PIN and ad-hoc generated biometric related key
powerAuthSDK.persistActivation(context, fragment, "Enable Biometric Authentication", "To enable biometric authentication, use the biometric sensor on your device.", pin, new IPersistActivationWithBiometricsListener() {
@Override
public void onBiometricDialogCancelled() {
// Biometric enrolment cancelled by user
}
@Override
public void onBiometricDialogSuccess() {
// success, activation has been persisted
}
@Override
public void onBiometricDialogFailed(@NonNull PowerAuthErrorException error) {
// failure, typically as a result of API misuse, or a biometric authentication failure
}
});
Also, you can use the following code to create activation with the best granularity control:
val authentication = PowerAuthAuthentication.persistWithPasswordAndBiometry(pin, biometryFactorRelatedKey)
val result = powerAuthSDK.persistActivationWithAuthentication(context, authentication)
if (result != PowerAuthErrorCodes.SUCCEED) {
// happens only in case SDK was not configured or activation is not in the state to be persisted
}
PowerAuthAuthentication authentication = PowerAuthAuthentication.persistWithPasswordAndBiometry(pin, biometryFactorRelatedKey);
int result = powerAuthSDK.persistActivationWithAuthentication(context, authentication);
if (result != PowerAuthErrorCodes.SUCCEED) {
// happens only in case SDK was not configured or activation is not in the state to be persisted
}
Note that you currently need to obtain the biometry factor-related key yourself - you have to use BiometricPrompt.CryptoObject or integration with Android KeyStore to do so.
Validating User Inputs
The mobile SDK provides a couple of functions in ActivationCodeUtil class, helping with user input validation. You can:
- Parse activation code when it’s scanned from QR code
- Validate a whole code at once
- Validate recovery code or PUK
- Auto-correct characters typed on the fly
Validating Scanned QR Code
To validate an activation code scanned from QR code, you can use ActivationCodeUtil.parseFromActivationCode() function. You have to provide the code with or without the signature part. For example:
val scannedCode = "VVVVV-VVVVV-VVVVV-VTFVA#aGVsbG8.....gd29ybGQ="
val code = ActivationCodeUtil.parseFromActivationCode(scannedCode);
if (code?.activationCode == null) {
// Invalid code, QR code should contain a signature
return;
}
final String scannedCode = "VVVVV-VVVVV-VVVVV-VTFVA#aGVsbG8.....gd29ybGQ=";
final ActivationCode code = ActivationCodeUtil.parseFromActivationCode(scannedCode);
if (code == null || code.activationCode == null) {
// Invalid code, QR code should contain a signature
return;
}
Note that the signature is only formally validated in the function above. The actual signature verification is done in the activation process, or you can do it on your own:
val scannedCode = "VVVVV-VVVVV-VVVVV-VTFVA#aGVsbG8......gd29ybGQ="
val code = ActivationCodeUtil.parseFromActivationCode(scannedCode)
if (code?.activationCode == null) {
return
}
val codeBytes = code.activationCode.toByteArray()
val signatureBytes = Base64.decode(code.activationSignature, Base64.NO_WRAP)
if (!powerAuthSDK.verifyServerSignedData(codeBytes, signatureBytes, true)) {
// Invalid signature
}
final String scannedCode = "VVVVV-VVVVV-VVVVV-VTFVA#aGVsbG8......gd29ybGQ=";
final ActivationCode code = ActivationCodeUtil.parseFromActivationCode(scannedCode);
if (code == null || code.activationCode == null) {
return;
}
final byte[] codeBytes = code.activationCode.getBytes(Charset.defaultCharset());
final byte[] signatureBytes = Base64.decode(code.activationSignature, Base64.NO_WRAP);
if (!powerAuthSDK.verifyServerSignedData(codeBytes, signatureBytes, true)) {
// Invalid signature
}
Validating Entered Activation Code
To validate an activation code at once, you can call ActivationCodeUtil.validateActivationCode() function. You have to provide the code without the signature part. For example:
val isValid = ActivationCodeUtil.validateActivationCode("VVVVV-VVVVV-VVVVV-VTFVA")
val isInvalid = ActivationCodeUtil.validateActivationCode("VVVVV-VVVVV-VVVVV-VTFVA#aGVsbG8gd29ybGQ=")
boolean isValid = ActivationCodeUtil.validateActivationCode("VVVVV-VVVVV-VVVVV-VTFVA");
boolean isInvalid = ActivationCodeUtil.validateActivationCode("VVVVV-VVVVV-VVVVV-VTFVA#aGVsbG8gd29ybGQ=");
If your application is using your own validation, then you should switch to functions provided by SDK. The reason for that is that since SDK 1.0.0, all activation codes contain a checksum, so it’s possible to detect mistyped characters before you start the activation. Check our Activation Code documentation for more details.
Validating Recovery Code and PUK
To validate a recovery code at once, you can call ActivationCodeUtil.validateRecoveryCode() function. You can provide the whole code, which may or may not contain "R:" prefix. So, you can validate manually entered codes, but also codes scanned from QR. For example:
val isValid1 = ActivationCodeUtil.validateRecoveryCode("VVVVV-VVVVV-VVVVV-VTFVA")
val isValid2 = ActivationCodeUtil.validateRecoveryCode("R:VVVVV-VVVVV-VVVVV-VTFVA")
boolean isValid1 = ActivationCodeUtil.validateRecoveryCode("VVVVV-VVVVV-VVVVV-VTFVA");
boolean isValid2 = ActivationCodeUtil.validateRecoveryCode("R:VVVVV-VVVVV-VVVVV-VTFVA");
To validate PUK at once, you can call ActivationCodeUtil.validateRecoveryPuk() function:
val isValid = ActivationCodeUtil.validateRecoveryPuk("0123456789")
boolean isValid = ActivationCodeUtil.validateRecoveryPuk("0123456789");
Auto-Correcting Typed Characters
You can implement auto-correcting of typed characters by using ActivationCodeUtil.validateAndCorrectTypedCharacter() function in screens, where the user is supposed to enter an activation or recovery code. This technique is possible due to the fact that Base32 is constructed so that it doesn’t contain visually confusing characters. For example, 1 (number one) and I (capital I) are confusing, so only I is allowed. The benefit is that the provided function can correct typed 1 and translate it to I.
Here’s an example how to iterate over the string and validate it character by character:
/// Returns corrected character or null in case of error.
fun validateTypedCharacters(input: String): String? {
val length = input.length
val output = StringBuilder(length)
var offset = 0
while (offset < length) {
val codepoint = input.codePointAt(offset)
offset += Character.charCount(codepoint)
val corrected = ActivationCodeUtil.validateAndCorrectTypedCharacter(codepoint)
if (corrected == 0) {
return null
}
// Character.isBmpCodePoint(corrected) is always true
output.append(corrected.toChar())
}
return output.toString()
}
// validateTypedCharacter("v1") == "VI"
// validateTypedCharacter("9") == null
/// Returns corrected character or null in case of error.
@Nullable String validateTypedCharacters(@NonNull String input) {
final int length = input.length();
final StringBuilder output = new StringBuilder(length);
for (int offset = 0; offset < length; ) {
final int codepoint = input.codePointAt(offset);
offset += Character.charCount(codepoint);
final int corrected = ActivationCodeUtil.validateAndCorrectTypedCharacter(codepoint);
if (corrected == 0) {
return null;
}
// Character.isBmpCodePoint(corrected) is always true
output.append((char)corrected);
}
return output.toString();
}
// validateTypedCharacter("v1") == "VI"
// validateTypedCharacter("9") == null
Requesting Activation Status
To obtain detailed activation status information, use the following code:
// Check if there is some activation on the device
if (powerAuthSDK.hasValidActivation()) {
// If there is an activation on the device, check the status with server
powerAuthSDK.fetchActivationStatusWithCallback(context, object: IActivationStatusListener {
override fun onActivationStatusSucceed(status: ActivationStatus) {
// Activation state: State_Created, State_Pending_Commit, State_Active, State_Blocked, State_Removed, State_Deadlock
when (status.state) {
ActivationStatus.State_Pending_Commit ->
// Activation is awaiting commit on the server.
Log.i(TAG, "Waiting for commit")
ActivationStatus.State_Active ->
// Activation is valid and active.
Log.i(TAG, "Activation is active")
ActivationStatus.State_Blocked ->
// Activation is blocked. You can display unblock
// instructions to the user.
Log.i(TAG, "Activation is blocked")
ActivationStatus.State_Removed -> {
// Activation is no longer valid on the server.
// You can inform user about this situation and remove
// activation locally.
Log.i(TAG, "Activation is no longer valid")
powerAuthSDK.removeActivationLocal(context)
}
ActivationStatus.State_Deadlock -> {
// Local activation is technically blocked and no longer
// can be used for the signature calculations. You can inform
// user about this situation and remove activation locally.
Log.i(TAG, "Activation is technically blocked")
powerAuthSDK.removeActivationLocal(context)
}
ActivationStatus.State_Created -> Log.i(TAG, "Unknown state")
else -> Log.i(TAG, "Unknown state")
}
// Failed login attempts, remaining = max - current
val currentFailCount: Int = status.failCount
val maxAllowedFailCount: Int = status.maxFailCount
val remainingFailCount: Int = status.remainingAttempts
if (status.customObject != null) {
// Custom object contains any proprietary server specific data
}
}
override fun onActivationStatusFailed(t: Throwable) {
// Network error occurred, report it to the user
}
})
} else {
// No activation present on device
}
// Check if there is some activation on the device
if (powerAuthSDK.hasValidActivation()) {
// If there is an activation on the device, check the status with server
powerAuthSDK.fetchActivationStatusWithCallback(context, new IActivationStatusListener() {
@Override
public void onActivationStatusSucceed(ActivationStatus status) {
// Activation state: State_Created, State_Pending_Commit, State_Active, State_Blocked, State_Removed, State_Deadlock
switch (status.state) {
case ActivationStatus.State_Pending_Commit:
// Activation is awaiting commit on the server.
android.util.Log.i(TAG, "Waiting for commit");
break;
case ActivationStatus.State_Active:
// Activation is valid and active.
android.util.Log.i(TAG, "Activation is active");
break;
case ActivationStatus.State_Blocked:
// Activation is blocked. You can display unblock
// instructions to the user.
android.util.Log.i(TAG, "Activation is blocked");
break;
case ActivationStatus.State_Removed:
// Activation is no longer valid on the server.
// You can inform user about this situation and remove
// activation locally.
android.util.Log.i(TAG, "Activation is no longer valid");
powerAuthSDK.removeActivationLocal(context);
break;
case ActivationStatus.State_Deadlock:
// Local activation is technically blocked and no longer
// can be used for the signature calculations. You can inform
// user about this situation and remove activation locally.
android.util.Log.i(TAG, "Activation is technically blocked");
powerAuthSDK.removeActivationLocal(context);
break;
case ActivationStatus.State_Created:
// Activation is just created. This is the internal
// state on the server and therefore can be ignored
// on the mobile application.
default:
android.util.Log.i(TAG, "Unknown state");
break;
}
// Failed login attempts, remaining = max - current
int currentFailCount = status.failCount;
int maxAllowedFailCount = status.maxFailCount;
int remainingFailCount = status.getRemainingAttempts();
if (status.getCustomObject() != null) {
// Custom object contains any proprietary server specific data
}
}
@Override
public void onActivationStatusFailed(Throwable t) {
// Network error occurred, report it to the user
}
});
} else {
// No activation present on device
}
Note that the status fetch may fail at an unrecoverable error PowerAuthErrorCodes.PROTOCOL_UPGRADE, meaning that it’s not possible to upgrade the PowerAuth protocol to a newer version. In this case, it’s recommended to remove the activation locally.
To get more information about activation lifecycle, check the Activation States chapter available in our powerauth-crypto repository.
Data Signing
The main feature of the PowerAuth protocol is data signing. PowerAuth has two types of signatures:
- Symmetric Multi-Factor Signature: Suitable for most operations, such as login, new payment, or confirming changes in settings.
- Asymmetric Private Key Signature: Suitable for documents where a strong one-sided signature is desired.
- Symmetric Offline Multi-Factor Signature: Suitable for very secure operations, where the signature is validated over the out-of-band channel.
- Verify server signed data: Suitable for receiving arbitrary data from the server.
Symmetric Multi-Factor Signature
To sign request data, you need to first obtain user credentials (password, PIN code, biometric image) from the user. The task of obtaining the user credentials is used in more use-cases covered by the SDK. The core class is PowerAuthAuthentication that holds information about the used authentication factors:
// 1FA signature, uses device related key only.
val oneFactor = PowerAuthAuthentication.possession()
// 2FA signature - uses device related key and user PIN code.
val twoFactorPassword = PowerAuthAuthentication.possessionWithPassword("1234")
// 2FA signature, uses biometry factor-related key as a 2nd. factor.
// To obtain biometryFactorRelatedKey see "Fetching the Biometry Factor-Related Key for Authentication" chapter.
val twoFactorBiometry = PowerAuthAuthentication.possessionWithBiometry(biometryFactorRelatedKey)
// 1FA signature, uses device related key only.
PowerAuthAuthentication oneFactor = PowerAuthAuthentication.possession();
// 2FA signature - uses device related key and user PIN code.
PowerAuthAuthentication twoFactorPassword = PowerAuthAuthentication.possessionWithPassword("1234");
// 2FA signature, uses biometry factor-related key as a 2nd. factor.
// To obtain biometryFactorRelatedKey see "Fetching the Biometry Factor-Related Key for Authentication" chapter.
PowerAuthAuthentication twoFactorBiometry = PowerAuthAuthentication.possessionWithBiometry(biometryFactorRelatedKey);
When signing POST, PUT or DELETE requests, use request body bytes (UTF-8) as request data and the following code:
// 2FA signature - uses device related key and user PIN code
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
// Sign POST call with provided data made to URI with custom identifier "/payment/create"
val header = powerAuthSDK.requestSignatureWithAuthentication(context, authentication, "POST", "/payment/create", requestBodyBytes)
if (header.isValid) {
val httpHeaderKey = header.getKey()
val httpHeaderValue = header.getValue()
} else {
// In case of invalid configuration, invalid activation state or corrupted state data
}
// 2FA signature - uses device-related key and user PIN code
PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
// Sign POST call with provided data made to URI with custom identifier "/payment/create"
PowerAuthAuthorizationHttpHeader header = powerAuthSDK.requestSignatureWithAuthentication(context, authentication, "POST", "/payment/create", requestBodyBytes);
if (header.isValid()) {
String httpHeaderKey = header.getKey();
String httpHeaderValue = header.getValue();
} else {
// In case of invalid configuration, invalid activation state or corrupted state data
}
When signing GET requests, use the same code as above with normalized request data as described in specification, or (preferably) use the following helper method:
// 2FA signature - uses device-related key and user PIN code
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
// Sign GET call with provided query parameters made to URI with custom identifier "/payment/create"
val params = mapOf("param1" to "value1", "param2" to "value2")
val header = powerAuthSDK.requestGetSignatureWithAuthentication(context, authentication, "/payment/create", params)
if (header.isValid) {
val httpHeaderKey = header.getKey()
val httpHeaderValue = header.getValue()
} else {
// In case of invalid configuration, invalid activation state or corrupted state data
}
// 2FA signature - uses device-related key and user PIN code
PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
// Sign GET call with provided query parameters made to URI with custom identifier "/payment/create"
Map<String, String> params = new HashMap<>();
params.put("param1", "value1");
params.put("param2", "value2");
PowerAuthAuthorizationHttpHeader header = powerAuthSDK.requestGetSignatureWithAuthentication(context, authentication, "/payment/create", params);
if (header.isValid()) {
String httpHeaderKey = header.getKey();
String httpHeaderValue = header.getValue();
} else {
// In case of invalid configuration, invalid activation state or corrupted state data
}
The result of the signature is appropriate HTTP header - you are responsible for hooking up the header value in your request correctly. The process with libraries like OkHttp goes like this:
// Prepare the request builder
val builder: Request.Builder = Builder().url(endpoint)
// Compute PA signature header
val header = powerAuthSDK.requestSignatureWithAuthentication(context, signatureUnlockKeys, "POST", "/session/login", jsonBody)
if (!header.isValid) {
// request signature failed, for example due to incorrect activation status - cancel the process
return
}
// Add HTTP header in the request builder
builder.header(header.getKey(), header.getValue())
// Build the request, send it, and process the response...
// ...
// Prepare the request builder
final Request.Builder builder = new Request.Builder().url(endpoint);
// Compute PA signature header
PowerAuthAuthorizationHttpHeader header = powerAuthSDK.requestSignatureWithAuthentication(context, signatureUnlockKeys, "POST", "/session/login", jsonBody);
if (!header.isValid()) {
// request signature failed, for example due to incorrect activation status - cancel the process
return;
}
// Add HTTP header in the request builder
builder.header(header.getKey(), header.getValue());
// Build the request, send it, and process the response...
// ...
Request Synchronization
It is recommended that your application executes only one signed request at the time. The reason for that is that our signature scheme is using a counter as a representation of logical time. In other words, the order of request validation on the server is very important. If you issue more than one signed request at the same time, then the order is not guaranteed, and therefore one of the requests may fail. On top of that, Mobile SDK itself is using this type of signatures for its own purposes. For example, if you ask for token, then the SDK is using signed request to obtain the token’s data. To deal with this problem, Mobile SDK is providing a custom serial Executor, which can be used for signed requests execution:
powerAuthSDK.serialExecutor.execute {
// Recommended practice:
// 1. You have to calculate the PowerAuth signature here.
// 2. In case that you start yet another asynchronous operation from run(),
// then you have to wait for that operation's execution.
}
final Executor serialExecutor = powerAuthSDK.getSerialExecutor();
serialExecutor.execute(new Runnable() {
@Override
public void run() {
// Recommended practice:
// 1. You have to calculate the PowerAuth signature here.
// 2. In case that you start yet another asynchronous operation from run(),
// then you have to wait for that operation's execution.
}
});
Asymmetric Private Key Signature
Asymmetric Private Key Signature uses a private key stored in the PowerAuth secure vault. In order to unlock the secure vault and retrieve the private key, the user has to first authenticate using the symmetric multi-factor signature with at least two factors. This mechanism protects the private key on the device - the server plays a role of a “doorkeeper” and holds the vault unlock key.
This process is completely transparent on the SDK level. To compute an asymmetric private key signature, request user credentials (password, PIN, biometric image) and use the following code:
// Prepare the authentication object
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
// Get the data to be signed
val data: ByteArray = this.getMyData()
powerAuthSDK.signDataWithDevicePrivateKey(context, authentication, data, object: IDataSignatureListener {
override fun onDataSignedSucceed(signature: ByteArray) {
// Use data signature...
}
override fun onDataSignedFailed(t: Throwable) {
// Report error
}
})
// Prepare the authentication object
PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
// Get the data to be signed
byte[] data = this.getMyData();
powerAuthSDK.signDataWithDevicePrivateKey(context, authentication, data, new IDataSignatureListener() {
@Override
public void onDataSignedSucceed(byte[] signature) {
// Use data signature...
}
@Override
public void onDataSignedFailed(Throwable t) {
// Report error
}
});
Producing Signed JWT with Provided Claims
The asymmetric private key signatures described above can be used to sign claims provided by the developer and construct a signed JWT (signed using ES256 algorithm).
// Construct claims array
val claims = mapOf(
"sub" to "user-id",
"first_name" to "John",
"last_name" to "Appleseed"
)
// 2FA signature - uses device related key and user PIN code
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
// Unlock the secure vault, fetch the private key and perform data signing
powerAuthSDK.signJwtWithDevicePrivateKey(context, authentication, claims, object : IJwtSignatureListener {
override fun onJwtSignatureSucceed(jwt: String) {
// Use JWT value
}
override fun onJwtSignatureFailed(t: Throwable) {
// Authentication or network error
}
})
Symmetric Offline Multi-Factor Signature
This type of signature is very similar to Symmetric Multi-Factor Signature but the result is provided in the form of a simple, human-readable string (unlike the online version, where the result is an HTTP header). To calculate the signature, you need a typical PowerAuthAuthentication object to define all required factors, nonce and data to sign. The nonce and data should also be transmitted to the application over the OOB channel (for example, by scanning a QR code). Then the signature calculation is straightforward:
// Prepare the authentication object
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
val signature = powerAuthSDK.offlineSignatureWithAuthentication(context, authentication, "/confirm/offline/operation", data, nonce)
if (signature != null) {
Log.d(TAG, "Offline signature is: $signature")
} else {
// failure: session is probably invalid, or some required data is missing
}
// Prepare the authentication object
PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
final String signature = powerAuthSDK.offlineSignatureWithAuthentication(context, authentication, "/confirm/offline/operation", data, nonce);
if (signature != null) {
android.util.Log.d(TAG, "Offline signature is: " + signature);
} else {
// failure: session is probably invalid, or some required data is missing
}
The application has to show that calculated signature to the user now, and the user has to re-type that code into the web application for the verification.
You can alter the lenght of the signature components by using offlineSignatureComponentLength() function of PowerAuthConfiguration.Builder class.
Verify Server-Signed Data
This task is useful whenever you need to receive arbitrary data from the server and you need to be able to verify that the server has issued the data. The PowerAuthSDK provides a high-level method for validating data and associated signature:
// Validate data signed with the master server key
if (powerAuthSDK.verifyServerSignedData(data, signature, true)) {
// data is signed with server's private master key
}
// Validate data signed with the personalized server key
if (powerAuthSDK.verifyServerSignedData(data, signature, false)) {
// data is signed with the server's private key
}
// Validate data signed with the master server key
if (powerAuthSDK.verifyServerSignedData(data, signature, true)) {
// data is signed with server's private master key
}
// Validate data signed with the personalized server key
if (powerAuthSDK.verifyServerSignedData(data, signature, false)) {
// data is signed with the server's private key
}
Password Change
Since the device does not know the password and is unable to verify the password without the help of the server-side, you need to first call an endpoint that verifies a signature computed with the password. SDK offers two ways to do that.
The safe but typically slower way is to use the following code:
// Change password from "oldPassword" to "newPassword".
powerAuthSDK.changePassword(context, "oldPassword", "newPassword", object: IChangePasswordListener {
override fun onPasswordChangeSucceed() {
// Password was changed
}
override fun onPasswordChangeFailed(t: Throwable) {
// Error occurred
}
})
// Change password from "oldPassword" to "newPassword".
powerAuthSDK.changePassword(context, "oldPassword", "newPassword", new IChangePasswordListener() {
@Override
public void onPasswordChangeSucceed() {
// Password was changed
}
@Override
public void onPasswordChangeFailed(Throwable t) {
// Error occurred
}
})
This method calls /pa/v3/signature/validate under the hood with a 2FA signature with provided original password to verify the password correctness.
However, using this method does not usually fit the typical UI workflow of a password change. The method may be used in cases where an old password and a new password are on a single screen, and therefore are both available at the same time. In most mobile apps, however, the user first visits a screen to enter an old password, and then (if the password is OK), the user proceeds to the two-screen flow of a new password setup (select password, confirm password). In other words, the workflow works like this:
- Show a screen to enter an old password.
- Check an old password on the server.
- If the old password is OK, then let the user chose and confirm a new one.
- Change the password by re-encrypting the activation data.
For this purpose, you can use the following code:
// [1] Ask for an old password
val oldPassword = "1234"
// [2] Validate password on the server
powerAuthSDK.validatePassword(context, oldPassword, object: IValidatePasswordListener {
override fun onPasswordValid() {
// Proceed to the new password setup
}
override fun onPasswordValidationFailed(t: Throwable) {
// Retry entering an old password
}
})
// [3] Ask for new password
val newPassword = "2468"
// [4] Change the password locally
powerAuthSDK.changePasswordUnsafe(oldPassword, newPassword)
// [1] Ask for an old password
String oldPassword = "1234";
// [2] Validate password on the server
powerAuthSDK.validatePassword(context, oldPassword, new IValidatePasswordListener() {
@Override
public void onPasswordValid() {
// Proceed to the new password setup
}
@Override
public void onPasswordValidationFailed(Throwable t) {
// Retry entering an old password
}
});
// [3] Ask for new password
String newPassword = "2468";
// [4] Change the password locally
powerAuthSDK.changePasswordUnsafe(oldPassword, newPassword);
Now, beware! Since the device does not know the actual old password, you need to make sure that the old password is validated before you use it in unsafeChangePassword. In case you provide the wrong old password, it will be used to decrypt the original data, and these data will be encrypted using a new password. As a result, the activation data will be broken and irreversibly lost.
Working with passwords securely
PowerAuth mobile SDK uses the io.getlime.security.powerauth.core.Password object behind the scenes, to store the user’s password or PIN securely. The object automatically wipes out the plaintext password on its destroy, so there are no traces of sensitive data left in the memory. You can easily enhance your application’s runtime security by adopting this object in your code and this chapter explains in detail how to do it.
Problem explanation
If you store the user’s password in a simple string, there is a high probability that the content of the string will remain in the memory until the same region is reused by the underlying memory allocator. This is because the general memory allocator doesn’t clean up the region of memory being freed. It just updates its linked-list of free memory regions for future reuse, so the content of the allocated object typically remains intact. This has the following implications for your application:
-
If your application is using a system keyboard to enter the password or PIN, then the sensitive data will remain in memory in multiple copies for a while.
-
If the device’s memory is not stressed enough, then the application may remain in memory active for days.
The situation that the user’s password stays in memory for days may be critical in situations when the attacker has the device in possession. For example, if the device is lost or is in a repair shop. To minimize the risks, the Password object does the following things:
-
Always keeps the user’s password scrambled with random data, so it cannot be easily found by simple string search. The password in plaintext is revealed only for a short and well-defined time when it’s needed for the cryptographic operation.
-
Always clear buffer with the sensitive data before the object’s destruction.
-
Doesn’t provide a simple interface to reveal the password in plaintext1) and therefore it minimizes the risks of revealing the password by accident (like printing it to the log).
Note 1: There’s a validatePasswordComplexity() function that reveals the password in plaintext for a limited time for complexity validation purposes. The straightforward naming of the function allows you to find all its usages in your code and properly validate all code paths.
Special password object usage
PowerAuth mobile SDK allows you to use both strings and special password objects at input, so it’s up to you which way fits best for your purposes. For simplicity, this documentation uses strings for the passwords, but all code examples can be changed to utilize the Password object as well. For example, this is the modified code for Password Change:
// Change password from "oldPassword" to "newPassword".
val oldPass = Password("oldPassword")
val newPass = Password("newPassword")
powerAuthSDK.changePassword(context, oldPass, newPass, object: IChangePasswordListener {
override fun onPasswordChangeSucceed() {
// Password was changed
}
override fun onPasswordChangeFailed(t: Throwable) {
// Error occurred
}
})
// Change password from "oldPassword" to "newPassword".
Password oldPass = new Password("oldPassword");
Password newPass = new Password("newPassword")
powerAuthSDK.changePassword(context, oldPass, newPass, new IChangePasswordListener() {
@Override
public void onPasswordChangeSucceed() {
// Password was changed
}
@Override
public void onPasswordChangeFailed(Throwable t) {
// Error occurred
}
})
Entering PIN
If your application is using a system numeric keyboard to enter the user’s PIN then you can migrate to the Password object right now. We recommend you do the following things:
-
Implement your own PIN keyboard UI
-
Make sure that the password object is allocated and referenced only in the PIN keyboard controller and is deallocated when the user leaves the controller.
-
Use the
Password()object that allows you to manipulate the content of the PIN
Here’s the simple pseudo-controller example:
class EnterPinScene(val desiredPinLength: Int = 4) {
private var pinInstance: Password? = null
private val pin: Password get() = pinInstance ?: throw IllegalStateException()
fun onEnterScene() {
// Allocate password when entering to the scene.
// Constructor with no parameters creates a mutable Password.
pinInstance = Password()
}
fun onLeaveScene() {
// Dereference and destroy the password object, when the user is leaving
// the scene to safely wipe the content out of the memory.
//
// Make sure that this is done only after PowerAuth SDK finishes all operations
// started with this object at input.
pinInstance?.destroy()
pinInstance = null
}
fun onDeleteButtonAction() {
pin.removeLastCharacter()
}
fun onPinButtonAction(pinCharacter: Char) {
// Mutable password works with Unicode scalars, this is the example
// that works with an arbitrary character up to code point 0xFFFF.
// To add an arbitrary Unicode character, you need to convert it to code point first.
// See https://stackoverflow.com/questions/9834964/char-to-unicode-more-than-uffff-in-java
pin.addCharacter(pinCharacter.code)
if (pin.length() == desiredPinLength) {
onContinueAction(pin)
}
}
fun onPinButtonActionSimplified(pinIndex: Int) {
// This is a simplified version of onPinButtonAction() that use
// simple PIN button index as input.
if (pinIndex < 0 || pinIndex > 9) {
throw IllegalArgumentException("Wrong PIN index")
}
// You don't need to add 48 (code for character "0") to the index,
// unless your previous implementation was using number characters.
pin.addCharacter(48 + pinIndex)
if (pin.length() == desiredPinLength) {
onContinueAction(pin)
}
}
fun onContinueAction(pin: Password) {
// Do something with the entered pin...
}
}
Entering arbitrary password
Unfortunately, there’s no simple solution for this scenario. It’s quite difficult to re-implement the whole keyboard on your own, so we recommend you keep using the system keyboard. You can still create the Password object from an already entered string:
val passwordString = "nbusr123"
val password = Password(passwordString)
final String passwordString = "nbusr123";
final Password password = new Password(passwordString);
Create a password from the data
In case that passphrase is somehow created externally in the form of an array of bytes, then you can instantiate it from the Data object directly:
val passwordData = Base64.decode("bmJ1c3IxMjMK", Base64.NO_WRAP)
val password = Password(passwordData)
final byte[] passwordData = Base64.decode("bmJ1c3IxMjMK", Base64.NO_WRAP);
final Password password = new Password(passwordData);
Compare two passwords
To compare two passwords, use the isEqual(to:) method:
val password1 = Password("1234")
val password2 = Password("Hello")
val password3 = Password()
password3.addCharacter(0x31)
password3.addCharacter(0x32)
password3.addCharacter(0x33)
password3.addCharacter(0x34)
print("${password1.isEqualToPassword(password2)}") // false
print("${password1 == password3}") // true
final Password password1 = new Password("1234")
final Password password2 = new Password("Hello")
final Password password3 = new Password()
password3.addCharacter(0x31)
password3.addCharacter(0x32)
password3.addCharacter(0x33)
password3.addCharacter(0x34)
Log.d("TAG", (password1.isEqualToPassword(password2)).toString()) // false
Log.d("TAG", (password1.equals(password2)).toString()) // true
Validate password complexity
The Password object doesn’t provide functions that validate password complexity, but allows you to implement such functionality on your own:
enum class PasswordComplexity(val value: Int) {
WEAK(0),
GOOD(1),
STRONG(2);
companion object {
fun fromInt(value: Int): PasswordComplexity = values().first { it.value == value }
}
}
// This is an actual complexity validator that also accepts ByteArray at its input. You should avoid
// converting provided bytes into String or copy passphrase to another byte array to minimize risk
// of leaking the password in memory.
fun superPasswordValidator(password: ByteArray): PasswordComplexity {
// This is just an example, please do not use such trivial validation in your
// production application :)
if (password.size < 4) {
return PasswordComplexity.WEAK
} else if (password.size < 8) {
return PasswordComplexity.GOOD
}
return PasswordComplexity.STRONG
}
// Convenient wrapper to validatePasswordComplexity() method
fun Password.validateComplexity(): PasswordComplexity {
val resultValue = validatePasswordComplexity { passwordBytes ->
superPasswordValidator(passwordBytes).value
}
return PasswordComplexity.fromInt(resultValue)
}
You can use our Passphrase meter library as a proper password validation solution.
Biometric Authentication Setup
PowerAuth SDK for Android provides an abstraction on top of the base Biometric Authentication support. While the authentication / data signing itself is handled using the PowerAuthAuthentication object used in regular request signing, other biometry-related processes require their own API.
Check Biometric Authentication Status
You have to check for Biometric Authentication on three levels:
- System Availability: If a biometric scanner is present on the system.
- Activation Availability: If biometry factor data are available for given activation.
- Application Availability: If the user decides to use biometric authentication for the given app. (optional)
PowerAuth SDK for Android provides code for the first and second of these checks.
To check if you can use the biometric authentication, use our helper class:
// This method is equivalent to `BiometricManager.canAuthenticate() == BiometricManager.BIOMETRIC_SUCCESS`.
// Use it to check if the biometric authentication can be used at the moment.
val isBiometricAuthAvailable = BiometricAuthentication.isBiometricAuthenticationAvailable(context)
// For more fine-grained control about the actual biometric authentication status,
// you may use the following code:
when (BiometricAuthentication.canAuthenticate(context)) {
BiometricStatus.OK ->
print("Everything is OK")
BiometricStatus.NOT_SUPPORTED ->
print("device's hardware doesn't support biometry")
BiometricStatus.NOT_ENROLLED ->
print("there's no biometry data enrolled on the device")
BiometricStatus.NOT_AVAILABLE ->
print("The biometric authentication is not available at this time. Retry later.")
}
// If you want to adjust localized strings or icons presented to the user,
// you can use the following code to determine the type of biometry available
// on the system:
when (BiometricAuthentication.getBiometryType(context)) {
BiometryType.NONE ->
print("Biometry is not supported on the system.")
BiometryType.GENERIC ->
// It's not possible to determine the exact type of biometry.
// This occurs on Android 10+ systems when the device supports
// more than one type of biometric authentication. In this case,
// you should use generic terms in your UI, such as "Authenticate with biometry".
// This issue can also arise on devices that support a new type of biometry
// sensor, or on older, malfunctioning devices that fail to declare
// support for FEATURE_FINGERPRINT.
print("Biometry type is GENERIC")
BiometryType.FINGERPRINT ->
print("Fingerprint scanner is present on the device.")
BiometryType.FACE ->
print("Face scanner is present on the device.")
BiometryType.IRIS ->
print("Iris scanner is present on the device.")
}
// This method is equivalent to `BiometricManager.canAuthenticate() == BiometricManager.BIOMETRIC_SUCCESS`.
// Use it to check if the biometric authentication can be used at the moment.
boolean isBiometricAuthAvailable = BiometricAuthentication.isBiometricAuthenticationAvailable(context);
// For more fine-grained control about the actual biometric authentication status,
// you may use the following code:
switch (BiometricAuthentication.canAuthenticate(context)) {
case BiometricStatus.OK:
// everything's OK
case BiometricStatus.NOT_SUPPORTED:
// device's hardware doesn't support biometry
case BiometricStatus.NOT_ENROLLED:
// there's no biometry data enrolled on the device
case BiometricStatus.NOT_AVAILABLE:
// The biometric authentication is not available at this time.
// You may try to retry the operation later.
}
// If you want to adjust localized strings or icons presented to the user,
// you can use the following code to determine the type of biometry available
// on the system:
switch (BiometricAuthentication.getBiometryType(context)) {
case BiometryType.NONE:
// Biometry is not supported on the system.
case BiometryType.GENERIC:
// It's not possible to determine the exact type of biometry.
// This happens on Android 10+ systems, when the device supports
// more than one type of biometric authentication. In this case,
// you should use generic terms, like "Authenticate with biometry"
// for your UI.
case BiometryType.FINGERPRINT:
// Fingerprint scanner is present on the device.
case BiometryType.FACE:
// Face scanner is present on the device.
case BiometryType.IRIS:
// Iris scanner is present on the device.
}
To check if a given activation has biometry factor-related data available, use the following code:
// Does activation have biometric factor-related data in place?
val hasBiometryFactor = powerAuthSDK.hasBiometryFactor(context)
// Does activation have biometric factor-related data in place?
boolean hasBiometryFactor = powerAuthSDK.hasBiometryFactor(context);
The last check is fully under your control. By keeping the biometric settings flag, for example, a BOOL in SharedPreferences, you can show the user an expected biometric authentication status (in a disabled state, though) even in the case biometric authentication is not enabled or when no fingers are enrolled on the device.
Enable Biometric Authentication
In case an activation does not yet have biometry-related factor data, and you would like to enable biometric authentication support, the device must first retrieve the original private key from the secure vault for key derivation. As a result, you have to use a successful 2FA with a password to enable biometric authentication support.
Use the following code to enable biometric authentication using biometric authentication:
// Establish biometric data using the provided password
powerAuthSDK.addBiometryFactor(context, fragment, "Enable Biometric Authentication", "To enable biometric authentication, use the biometric sensor on your device.", "1234", object: IAddBiometryFactorListener {
override fun onAddBiometryFactorSucceed() {
// Everything went OK, biometric authentication is ready to be used
}
override fun onAddBiometryFactorFailed(error: PowerAuthErrorException) {
// Error occurred, report it to the user
}
})
// Establish biometric data using the provided password
powerAuthSDK.addBiometryFactor(context, fragment, "Enable Biometric Authentication", "To enable biometric authentication, use the biometric sensor on your device.", "1234", new IAddBiometryFactorListener() {
@Override
public void onAddBiometryFactorSucceed() {
// Everything went OK, biometric authentication is ready to be used
}
@Override
public void onAddBiometryFactorFailed(@NonNull PowerAuthErrorException error) {
// Error occurred, report it to the user
}
});
By default, PowerAuth SDK asks the user to authenticate with the biometric sensor also during the setup procedure (or during the activation persist). To alter this behavior, use the following code to change the PowerAuthKeychainConfiguration provided to the PowerAuthSDK instance:
val keychainConfig = PowerAuthKeychainConfiguration.Builder()
.authenticateOnBiometricKeySetup(false)
.build()
// Apply keychain configuration
val powerAuthSDK = PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(getApplicationContext())
PowerAuthKeychainConfiguration keychainConfig = new PowerAuthKeychainConfiguration.Builder()
.authenticateOnBiometricKeySetup(false)
.build();
// Apply keychain configuration
PowerAuthSDK powerAuthSDK = new PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(getApplicationContext());
Note that the RSA key pair is internally generated for the configuration above. That may take more time on older devices than the default configuration. Your application should display a waiting indicator on its own because SDK doesn’t display an authentication dialog during the key-pair generation.
Disable Biometric Authentication
You can remove biometric-related factor data used by biometric authentication support by simply removing the related key locally, using this one-liner:
powerAuthSDK.removeBiometryFactor(context)
// Remove biometric data
powerAuthSDK.removeBiometryFactor(context);
Fetching the Biometry Factor-Related Key for Authentication
To obtain an encrypted biometry factor-related key for authentication, call the following code:
// Authenticate user with biometry and obtain encrypted biometry factor related key.
powerAuthSDK.authenticateUsingBiometrics(context, fragment, "Sign in", "Use the biometric sensor on your device to continue", object: IAuthenticateWithBiometricsListener {
override fun onBiometricDialogCancelled(userCancel: Boolean) {
// User canceled the operation
}
override fun onBiometricDialogSuccess(authentication: PowerAuthAuthentication) {
// User authenticated to use the provided authentication object for other tasks.
}
override fun onBiometricDialogFailed(error: PowerAuthErrorException) {
// Biometric authentication failed
val biometricErrorInfo = error.additionalInformation as? BiometricErrorInfo
if (biometricErrorInfo != null) {
if (biometricErrorInfo.isErrorPresentationRequired) {
// The application should present the reason for the biometric authentication failure to the user.
//
// If you don't disable the error dialog provided by the PowerAuth mobile SDK, then this may happen
// only when you try to use the biometric authentication while the biometric factor is not configured
// in the PowerAuthSDK instance.
val localizedMessage = biometricErrorInfo.getLocalizedErrorMessage(context, null)
}
} else {
// Other reasons for failure
}
}
})
// Authenticate user with biometry and obtain encrypted biometry factor related key.
powerAuthSDK.authenticateUsingBiometrics(context, fragment, "Sign in", "Use the biometric sensor on your device to continue", new IAuthenticateWithBiometricsListener() {
@Override
public void onBiometricDialogCancelled(boolean userCancel) {
// User canceled the operation
}
@Override
public void onBiometricDialogSuccess(PowerAuthAuthentication authentication) {
// User authenticated to use the provided authentication object for other tasks.
}
@Override
public void onBiometricDialogFailed(PowerAuthErrorException error) {
// Biometric authentication failed
if (error.getAdditionalInfo() instanceof BiometricErrorInfo) {
BiometricErrorInfo biometricErrorInfo = (BiometricErrorInfo) error.getAdditionalInfo();
if (biometricErrorInfo.isErrorPresentationRequired()) {
// The application should present the reason for the biometric authentication failure to the user.
//
// If you don't disable the error dialog provided by the PowerAuth mobile SDK, then this may happen
// only when you try to use the biometric authentication while the biometric factor is not configured
// in the PowerAuthSDK instance.
String localizedMessage = biometricErrorInfo.getLocalizedErrorMessage(context, null);
}
} else {
// Other reasons for failure
}
}
});
Note that if the biometric authentication fails with too many attempts in a row (e.g. biometry is temporarily or permanently locked out), then PowerAuth SDK will generate an invalid biometry factor related key, and the success is reported. This is an intended behavior and as a result, it typically leads to unsuccessful authentication on the server and an increased counter of failed attempts. The purpose of this is to limit the number of attempts for attackers to deceive the biometry sensor.
Facial Biometrics on Android
Currently, facial authentication only works with several Android device models. This is because to implement facial authentication securely, the PowerAuth SDK needs to protect the biometry-related key in the Android Keystore with a biometric sensor. This type of secure storage is only supported on devices with the BIOMETRIC_STRONG (class 3) sensor type, as explained in the official documentation:
- https://source.android.com/docs/security/features/biometric
The Android source codes contain a list of devices with strong biometry support.
Biometry Factor-Related Key Lifetime
By default, the biometry factor-related key is invalidated after the biometry enrolled in the system is changed. For example, if the user adds or removes the finger or enrolls with a new face, then the biometry factor-related key is no longer available for the signing operation. To change this behavior, you have to provide the PowerAuthKeychainConfiguration object with the linkBiometricItemsToCurrentSet parameter set to false and use that configuration for the PowerAuthSDK instance construction:
// Use false for the 'linkBiometricItemsToCurrentSet' parameter.
val keychainConfig = PowerAuthKeychainConfiguration.Builder()
.linkBiometricItemsToCurrentSet(false)
.build()
// Apply keychain configuration
val powerAuthSDK = PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(getApplicationContext())
// Use false for the 'linkBiometricItemsToCurrentSet' parameter.
PowerAuthKeychainConfiguration keychainConfig = new PowerAuthKeychainConfiguration.Builder()
.linkBiometricItemsToCurrentSet(false)
.build();
// Apply keychain configuration
PowerAuthSDK powerAuthSDK = new PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(getApplicationContext());
Be aware that the configuration above is effective only for the new keys. So, if your application is already using the biometry factor-related key with a different configuration, then the configuration change doesn’t change the existing key. You have to disable and enable biometry to apply the change.
Biometric Authentication Details
The BiometricAuthentication class is a high-level interface that provides interfaces related to biometric authentication for the SDK or for application purposes. The class hides all technical details, so it can be safely used also on systems that don’t provide biometric interfaces, or if the system has no biometric sensor available. The implementation under the hood uses androidx.biometric.BiometricPrompt and androidx.biometric.BiometricManager classes.
Customize Biometric Dialog Resources
To customize the strings used in biometric authentication, you can use BiometricDialogResources in the following manner:
// Prepare new strings, colors, etc...
val newStrings = BiometricDialogResources.Strings(... constructor with string ids ...)
// Build new resources object.
// If you omit some custom resources object, then the Builder will replace that with resources bundled in SDK.
val resources = BiometricDialogResources.Builder()
.setStrings(newStrings)
.build()
// Set resources to BiometricAuthentication
BiometricAuthentication.setBiometricDialogResources(resources)
// Prepare new strings, colors, etc...
final BiometricDialogResources.Strings newStrings = new BiometricDialogResources.Strings(... constructor with string ids ...);
// Build new resources object.
// If you omit some custom resources object, then the Builder will replace that with resources bundled in SDK.
final BiometricDialogResources resources = new BiometricDialogResources.Builder()
.setStrings(newStrings)
.build();
// Set resources to BiometricAuthentication
BiometricAuthentication.setBiometricDialogResources(resources);
Disable Error Dialog After Failed Biometry
If you prefer not to allow the PowerAuth mobile SDK to display its own error dialog, you can disable this feature globally. In this case, your application will need to handle all error situations through its own user interface. Use the following code to disable the error dialog:
BiometricAuthentication.setBiometricErrorDialogDisabled(true)
When the error dialog is disabled, your application should inform the user of the reason for the failure. Handling this might be somewhat tricky because there are situations where the biometric authentication dialog is not displayed at all, and the failure is reported directly to the application. To address this, you can use the BiometricErrorInfo class, which is associated with the reported PowerAuthErrorException. The code snippet below outlines how to determine the situation:
// Authenticate user with biometry and obtain encrypted biometry factor related key.
powerAuthSDK.authenticateUsingBiometrics(context, fragment, "Sign in", "Use the biometric sensor on your device to continue", object: IAuthenticateWithBiometricsListener {
override fun onBiometricDialogCancelled(userCancel: Boolean) {
// User or system canceled the operation
}
override fun onBiometricDialogSuccess(authentication: PowerAuthAuthentication) {
// Success
}
override fun onBiometricDialogFailed(error: PowerAuthErrorException) {
val biometricErrorInfo = error.additionalInformation as? BiometricErrorInfo
if (biometricErrorInfo != null) {
if (biometricErrorInfo.isErrorPresentationRequired) {
// Application should present the reason of biometric authentication failure to the user
val localizedMessage = biometricErrorInfo.getLocalizedErrorMessage(context, null)
}
} else {
// Other reasons for failure
}
}
})
Note that you still should Customize Biometric Dialog Resources to get a proper localized error message.
Biometric Authentication Confirmation
On Android 10+ systems, it’s possible to configure BiometricPrompt to ask for an additional confirmation after the user is successfully authenticated. The default behavior for PowerAuth Mobile SDK is that such confirmation is not required. To change this behavior, you have to provide the PowerAuthKeychainConfiguration object with the confirmBiometricAuthentication parameter set to true and use that configuration for the PowerAuthSDK instance construction:
// Use true for the 'confirmBiometricAuthentication' parameter.
val keychainConfig = PowerAuthKeychainConfiguration.Builder()
.confirmBiometricAuthentication(true)
.build()
// Apply keychain configuration
val powerAuthSDK = PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(context)
// Use true for the 'confirmBiometricAuthentication' parameter.
PowerAuthKeychainConfiguration keychainConfig = new PowerAuthKeychainConfiguration.Builder()
.confirmBiometricAuthentication(true)
.build();
// Apply keychain configuration
PowerAuthSDK powerAuthSDK = new PowerAuthSDK.Builder(configuration)
.keychainConfiguration(keychainConfig)
.build(getApplicationContext());
Activation Removal
You can remove activation using several ways - the choice depends on the desired behavior.
Simple Device-Only Removal
You can clear activation data anytime from the SharedPreferences. The benefit of this method is that it does not require help from the server, and the user does not have to be logged in. The issue with this removal method is simple: The activation still remains active on the server side. This, however, does not have to be an issue in your case.
To remove only data related to PowerAuth SDK for Android, use the following code:
powerAuthSDK.removeActivationLocal(context)
powerAuthSDK.removeActivationLocal(context);
Removal via Authenticated Session
Suppose your server uses an authenticated session to keep the users logged in. In that case, you can combine the previous method with calling your proprietary endpoint to remove activation for the currently logged-in user. The advantage of this method is that activation does not remain active on the server. The issue is that the user has to be logged in (the session must be active and must have an activation ID stored) and that you have to publish your own method to handle this use case.
The code for this activation removal method is as follows:
// Use custom call to proprietary server endpoint to remove activation.
//The user must be logged in at this moment, so that the session can find
// associated activation ID
this.httpClient.post(null, "/custom/activation/remove", object: ICustomListener {
override fun onSucceed() {
powerAuthSDK.removeActivationLocal(context)
}
override fun onFailed(t: Throwable) {
// Error occurred, report it to the user
}
})
// Use custom call to proprietary server endpoint to remove activation.
//The user must be logged in at this moment, so that the session can find
// associated activation ID
this.httpClient.post(null, "/custom/activation/remove", new ICustomListener() {
@Override
public void onSucceed() {
powerAuthSDK.removeActivationLocal(context);
}
@Override
public void onFailed(Throwable t) {
// Error occurred, report it to the user
}
});
Removal via Signed Request
PowerAuth Standard RESTful API has a default endpoint /pa/v3/activation/remove for an activation removal. This endpoint uses a signature verification for looking up the activation to be removed. The benefit of this method is that it is already present in both PowerAuth SDK for Android and PowerAuth Standard RESTful API - nothing has to be programmed. Also, the user does not have to be logged in to use it. However, the user has to authenticate using 2FA with either password or biometric authentication.
Use the following code for an activation removal using a signed request:
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
// Remove activation using the provided authentication object
powerAuthSDK.removeActivationWithAuthentication(context, authentication, object: IActivationRemoveListener {
override fun onActivationRemoveSucceed() {
// OK, activation was removed
}
override fun onActivationRemoveFailed(t: Throwable) {
// Report error to user
}
})
PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
// Remove activation using the provided authentication object
powerAuthSDK.removeActivationWithAuthentication(context, authentication, new IActivationRemoveListener() {
@Override
public void onActivationRemoveSucceed() {
// OK, activation was removed
}
@Override
public void onActivationRemoveFailed(Throwable t) {
// Report error to user
}
})
End-To-End Encryption
Currently, PowerAuth SDK supports two basic modes of end-to-end encryption, based on the ECIES scheme:
- In an “application” scope, the encryptor can be acquired and used during the whole lifetime of the application.
- In an “activation” scope, the encryptor can be acquired only if
PowerAuthSDKhas a valid activation. The encryptor created for this mode is cryptographically bound to the parameters agreed during the activation process. You can combine this encryption with PowerAuth Symmetric Multi-Factor Signature in “encrypt-then-sign” mode.
For both scenarios, you need to acquire an EciesEncryptor object, which will then provide an interface for the request encryption and the response decryption. The object currently provides only low-level encryption and decryption methods, so you need to implement your own JSON (de)serialization and request and response processing.
The following steps are typically required for a full E2EE request and response processing:
- Acquire the right encryptor from the
PowerAuthSDKinstance. For example:// Encryptor for "application" scope. val encryptor = powerAuthSDK.eciesEncryptorForApplicationScope // ...or similar, for an "activation" scope. val encryptor = powerAuthSDK.getEciesEncryptorForActivationScope(context) -
Serialize your request payload, if needed, into a sequence of bytes. This step typically means that you need to serialize your model object into a JSON-formatted sequence of bytes.
- Make sure that the PowerAuth SDK instance has time synchronized with the server:
val timeService = powerAuthSDK.timeSynchronizationService if (!timeService.isTimeSynchronized) { timeService.synchronizeTime(object : ITimeSynchronizationListener { override fun onTimeSynchronizationSucceeded() { // Success } override fun onTimeSynchronizationFailed(t: Throwable) { // Failure } }) } - Encrypt your payload:
val cryptogram = encryptor.encryptRequest(payloadData) if (cryptogram == null) { // cannot encrypt data } - Construct a JSON from the provided cryptogram object. The dictionary with the following keys is expected:
ephemeralPublicKeyproperty fill withcryptogram.getKeyBase64()encryptedDataproperty fill withcryptogram.getBodyBase64()macproperty fill withcryptogram.getMacBase64()nonceproperty fill withcryptogram.getNonceBase64()timestampproperty fill withcryptogram.getTimestamp()
So, the final request JSON should look like this:
{ "ephemeralPublicKey" : "BASE64-DATA-BLOB", "encryptedData" : "BASE64-DATA-BLOB", "mac" : "BASE64-DATA-BLOB", "nonce" : "BASE64-NONCE", "timestamp" : 1694172789256 } - Add the following HTTP header (for signed requests, see note below):
// Acquire a "metadata" object, which contains additional information for the request construction val metadata = encryptor.metadata val httpHeaderName = metadata.httpHeaderKey val httpHeaderValue = metadata.httpHeaderValueNote, that if an “activation” scoped encryptor is combined with PowerAuth Symmetric Multi-Factor signature, then this step is not required. The signature’s header already contains all the information required for proper request decryption on the server.
- Fire your HTTP request and wait for a response
- In case that non-200 HTTP status code is received, then the error processing is identical to a standard RESTful response defined in our protocol. So, you can expect a JSON object with
"error"and"message"properties in the response.
- In case that non-200 HTTP status code is received, then the error processing is identical to a standard RESTful response defined in our protocol. So, you can expect a JSON object with
- Decrypt the response. The received JSON typically looks like this:
{ "encryptedData" : "BASE64-DATA-BLOB", "mac" : "BASE64-DATA-BLOB", "nonce" : "BASE64-NONCE", "timestamp" : 1694172789256 }So, you need to create yet another “cryptogram” object, but with only two properties set:
val responseCryptogram = EciesCryptogram(response.encryptedData, response.mac) val responseData = encryptor.decryptResponse(responseCryptogram) if (responseData == null) { // failed to decrypt response data } - And finally, you can process your received response.
As you can see, the E2EE is quite a non-trivial task. We recommend contacting us before using an application-specific E2EE. We can provide you with more support on a per-scenario basis, especially if we first understand what you are trying to achieve with end-to-end encryption in your application.
Secure Vault
PowerAuth SDK for Android has basic support for an encrypted secure vault. At this moment, the only supported method allows your application to establish an encryption / decryption key with a given index. The index represents a “key number” - your identifier for a given key. Different business logic purposes should have encryption keys with different index values.
On the server side, all secure vault-related work is concentrated in a /pa/v3/vault/unlock endpoint of PowerAuth Standard RESTful API. To receive data from this response, the call must be authenticated with at least 2FA (using a password or PIN).
The secure vault mechanism does not support biometry by default. Use PIN code or password-based authentication for unlocking the secure vault, or ask your server developers to enable biometry for vault unlock call by configuring the PowerAuth Server instance.
Obtaining Encryption Key
To obtain an encryption key with a given index, use the following code:
// 2FA signature. It uses device-related key and user PIN code.
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
// Select custom key index
val index = 1000L
// Fetch the encryption key with the given index
powerAuthSDK.fetchEncryptionKey(context, authentication, index, object: IFetchEncryptionKeyListener {
override fun onFetchEncryptionKeySucceed(encryptedEncryptionKey: ByteArray) {
// ... use the encryption key to encrypt or decrypt data
}
override fun onFetchEncryptionKeyFailed(t: Throwable) {
// Report error
}
})
// 2FA signature. It uses device device-related key and user PIN code.
PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
// Select custom key index
long index = 1000L;
// Fetch the encryption key with the given index
powerAuthSDK.fetchEncryptionKey(context, authentication, index, new IFetchEncryptionKeyListener() {
@Override
public void onFetchEncryptionKeySucceed(byte[] encryptedEncryptionKey) {
// ... use the encryption key to encrypt or decrypt data
}
@Override
public void onFetchEncryptionKeyFailed(Throwable t) {
// Report error
}
})
Recovery Codes
The recovery codes allow your users to recover their activation in case their device is lost or stolen. Before you start, please read the Activation Recovery document, available in our powerauth-crypto repository.
To recover an activation, the user has to re-type two separate values:
- Recovery Code itself, which is very similar to an activation code. So you can detect typing errors before you submit such code to the server.
- PUK, which is an additional numeric value and acts as a one-time password in the scheme.
PowerAuth currently supports two basic types of recovery codes:
- Recovery Code bound to a previous PowerAuth activation.
- This type of code can be obtained only in an already-activated application.
- This type of code has only one PUK available, so only one recovery operation is possible.
- The activation associated with the code is removed once the recovery operation succeeds.
- Recovery Code delivered via OOB channel, typically in the form of a securely printed postcard, delivered by the post service.
- This type of code has typically more than one PUK associated with the code, so it can be used multiple times.
- The user has to keep that postcard in a safe and secure place, and mark already used PUKs.
- The code delivery must be confirmed by the user before the code can be used for a recovery operation.
The feature is not automatically available. It must be enabled and configured on the PowerAuth Server. If it’s so, then your mobile application can use several methods related to this feature.
Getting Recovery Data
If the recovery data was received during the activation process, then you can later display that information to the user. To check the existence of recovery data and get that information, use the following code:
if (!powerAuthSDK.hasActivationRecoveryData()) {
// Recovery information is not available
return
}
// 2FA signature - uses device-related key and user PIN code
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
powerAuthSDK.getActivationRecoveryData(context, authentication, object: IGetRecoveryDataListener {
override fun onGetRecoveryDataSucceeded(recoveryData: RecoveryData) {
val recoveryCode = recoveryData.recoveryCode
val puk = recoveryData.puk
// Show values on the screen...
}
override fun onGetRecoveryDataFailed(t: Throwable) {
// Report error
}
})
if (!powerAuthSDK.hasActivationRecoveryData()) {
// Recovery information is not available
return;
}
// 2FA signature - uses device-related key and user PIN code
PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
powerAuthSDK.getActivationRecoveryData(context, authentication, new IGetRecoveryDataListener() {
@Override
public void onGetRecoveryDataSucceeded(RecoveryData recoveryData) {
final String recoveryCode = recoveryData.recoveryCode;
final String puk = recoveryData.puk;
// Show values on the screen...
}
@Override
public void onGetRecoveryDataFailed(Throwable t) {
// Report error
}
});
The obtained information is very sensitive, so you should be very careful how your application manipulates the received values:
- You should never store
recoveryCodeorpukon the device. - You should never print the values to the debug log.
- You should never send the values over the network.
- You should never copy the values to the clipboard.
- You should require a PIN code every time to display the values on the screen.
- You should warn the user that taking a screenshot of the values is not recommended.
- Do not cache the values in RAM.
You should inform the user that:
- Making a screenshot when values are displayed on the screen is dangerous.
- The user should write down those values on paper and keep it as safe as possible for future use.
Confirm Recovery Postcard
The recovery postcard can contain the recovery code and multiple PUK values on one printed card. Due to security reasons, this kind of recovery code cannot be used for the recovery operation before the user confirms its physical delivery. To confirm such recovery code, use the following code:
// 2FA signature with possession factor is required
val authentication = PowerAuthAuthentication.possessionWithPassword("1234")
val recoveryCode = "VVVVV-VVVVV-VVVVV-VTFVA" // You can also use code scanned from QR
powerAuthSDK.confirmRecoveryCode(context, authentication, recoveryCode, object: IConfirmRecoveryCodeListener {
override fun onRecoveryCodeConfirmed(alreadyConfirmed: Boolean) {
if (alreadyConfirmed) {
android.util.Log.d(TAG, "Recovery code has been already confirmed. This is not an error, just information.")
} else {
android.util.Log.d(TAG, "Recovery code has been successfully confirmed.")
}
}
override fun onRecoveryCodeConfirmFailed(t: Throwable) {
// Report error
}
})
// 2FA signature with possession factor is required
final PowerAuthAuthentication authentication = PowerAuthAuthentication.possessionWithPassword("1234");
final String recoveryCode = "VVVVV-VVVVV-VVVVV-VTFVA" // You can also use code scanned from QR
powerAuthSDK.confirmRecoveryCode(context, authentication, recoveryCode, new IConfirmRecoveryCodeListener{
@Override
public void onRecoveryCodeConfirmed(boolean alreadyConfirmed) {
if (alreadyConfirmed) {
android.util.Log.d(TAG, "Recovery code has been already confirmed. This is not an error, just information.");
} else {
android.util.Log.d(TAG, "Recovery code has been successfully confirmed.");
}
}
@Override
public void onRecoveryCodeConfirmFailed(Throwable t) {
// Report error
}
});
The alreadyConfirmed boolean indicates that the code was already confirmed in the past. You can choose a different “success” screen, describing that the user has already confirmed such code. Also, note that codes bound to the activations are already confirmed.
Token-Based Authentication
WARNING: Before you start using access tokens, please visit our wiki page for powerauth-crypto for more information about this feature.
The tokens are simple, locally cached objects, producing timestamp-based authorization headers. Be aware that tokens are NOT a replacement for general PowerAuth signatures. They are helpful in situations when the signatures are too heavy or too complicated for implementation. Each token has the following properties:
- It needs a PowerAuth signature for its creation (e.g., you need to provide a
PowerAuthAuthenticationobject) - It has a unique identifier on the server. This identifier is not exposed to the public API, but you can reveal that value in the debugger.
- It has a symbolic name (e.g., “MyToken”) defined by the application programmer to identify already created tokens.
- It can generate timestamp-based authorization HTTP headers.
- It can be used concurrently. Token’s private data doesn’t change over time.
- The token is associated with the
PowerAuthSDKinstance. So, you can use the same symbolic name in multiple SDK instances, and each created token will be unique. - Tokens are persisted in the
KeychainFactoryservice and cached in the memory. - Once the parent
PowerAuthSDKinstance loses its activation, all its tokens are removed from the local database.
Getting Token
To get an access token, you can use the following code:
// 1FA signature - uses device-related key
val authentication = PowerAuthAuthentication.possession()
val cancelableTask = powerAuthSDK.tokenStore.requestAccessToken(context, "MyToken", authentication, object: IGetTokenListener {
override fun onGetTokenSucceeded(powerAuthToken: PowerAuthToken) {
// the token has been successfully acquired
}
override fun onGetTokenFailed(throwable: Throwable) {
// an error occurred
}
})
// 1FA signature - uses device-related key
final PowerAuthAuthentication authentication = PowerAuthAuthentication.possession();
final PowerAuthTokenStore tokenStore = powerAuthSDK.getTokenStore();
final ICancelable task = tokenStore.requestAccessToken(context, "MyToken", authentication, new IGetTokenListener() {
@Override
public void onGetTokenSucceeded(@NonNull PowerAuthToken powerAuthToken) {
// the token has been successfully acquired
}
@Override
public void onGetTokenFailed(@NonNull Throwable throwable) {
// an error occurred
}
});
The request is performed synchronously or asynchronously depending on whether the token is locally cached on the device. You can test this situation by calling tokenStore.hasLocalToken(context, "MyToken"). If the operation is asynchronous, then requestAccessToken() returns a cancellable task.
Generating Authorization Header
Use the following code to generate an authorization header:
val task = tokenStore.generateAuthorizationHeader(context, "MyToken", object : IGenerateTokenHeaderListener {
override fun onGenerateTokenHeaderSucceeded(header: PowerAuthAuthorizationHttpHeader) {
val httpHeaderKey = header.key
val httpHeaderValue = header.value
}
override fun onGenerateTokenHeaderFailed(t: Throwable) {
// Failure
}
})
Once you have a PowerAuthToken object, then you can use also a synchronous code to generate an authorization header:
val header: PowerAuthAuthorizationHttpHeader = token.generateHeader()
if (header.isValid) {
// Header is valid, you can construct an HTTP header...
val httpHeaderKey = header.key
val httpHeaderValue = header.value
} else {
// handle error
}
PowerAuthAuthorizationHttpHeader header = token.generateHeader();
if (header.isValid()) {
// Header is valid, you can construct an HTTP header...
String httpHeaderKey = header.key;
String httpHeaderValue = header.value;
} else {
// handle error
}
The synchronous example above is safe to use only if you’re sure that the time is already synchronized with the server.
Removing Token From the Server
To remove the token from the server, you can use the following code:
powerAuthSDK.tokenStore.removeAccessToken(context, "MyToken", object: IRemoveTokenListener {
override fun onRemoveTokenSucceeded() {
Log.d(TAG, "Token has been removed")
}
override fun onRemoveTokenFailed(t: Throwable) {
// handle HTTP error
}
})
powerAuthSDK.getTokenStore().removeAccessToken(context, "MyToken", new IRemoveTokenListener() {
@Override
public void onRemoveTokenSucceeded() {
android.util.Log.d(TAG, "Token has been removed");
}
@Override
public void onRemoveTokenFailed(@NonNull Throwable t) {
// handle HTTP error
}
});
Removing Token Locally
To remove the token locally, you can simply use the following code:
// Remove just one token
powerAuthSDK.tokenStore.removeLocalToken(context, "MyToken")
// Remove all local tokens
powerAuthSDK.tokenStore.removeAllLocalTokens(context)
// Remove just one token
powerAuthSDK.getTokenStore().removeLocalToken(context, "MyToken");
// Remove all local tokens
powerAuthSDK.getTokenStore().removeAllLocalTokens(context);
Note that by removing tokens locally, you will lose control of the tokens stored on the server.
External Encryption Key
The PowerAuthSDK allows you to specify an external encryption key (called EEK in our terminology) that can additionally protect the knowledge and the biometry factor keys. This feature is typically used to create a chain of activations where one instance of PowerAuthSDK is primary and unlocks access to all secondary activations.
The external encryption key has to be set before the activation is created, or can be added later. The internal state of PowerAuthSDK contains information that the factor keys are protected with EEK, so EEK must be known at the time of PowerAuth signature is calculated. You have three options on how to configure the key:
- Assign EEK into
PowerAuthConfiguration.Builderat the time ofPowerAuthSDKobject creation.- This is the most convenient way of using EEK, but the key must be known at the time of the
PowerAuthSDKinstantiation. - Once the
PowerAuthSDKinstance creates a new activation, then the factor keys will be automatically protected with EEK.
- This is the most convenient way of using EEK, but the key must be known at the time of the
- Use
PowerAuthSDK.setExternalEncryptionKey()to set EEK after thePowerAuthSDKinstance is created.- This is useful in case EEK is not known during the
PowerAuthSDKinstance creation. - You can set the key in any
PowerAuthSDKstate, but be aware that the method will fail in case the instance has a valid activation that doesn’t use EEK. - It’s safe to set the same EEK multiple times.
- This is useful in case EEK is not known during the
- Use
PowerAuthSDK.addExternalEncryptionKey()to add EEK and protect the factor keys in casePowerAuthSDKhas already a valid activation.- This method is useful in case
PowerAuthSDKalready has a valid activation, but it doesn’t use EEK yet. - The method automatically adds EEK into the internal configuration structure, but be aware, that all future
PowerAuthSDKusages (e.g. after app restart) require setting EEK by configuration, or by thesetExternalEncryptionKey()method.
- This method is useful in case
You can remove EEK from an existing activation if the key is no longer required. To do this, use the PowerAuthSDK.removeExternalEncryptionKey() method. Be aware, that EEK must be set by configuration, or by the setExternalEncryptionKey() method before you call the remove method. You can also use the PowerAuthSDK.hasExternalEncryptionKey() function to test whether the key is already set and in use.
Synchronized Time
The PowerAuth mobile SDK internally uses time synchronized with the PowerAuth Server for its cryptographic functions, such as End-To-End Encryption or Token-Based Authentication. The synchronized time can also be beneficial for your application. For example, if you want to display a time-sensitive message or countdown to your users, you can take advantage of this service.
Use the following code to get the service responsible for the time synchronization:
val timeService = powerAuthSDK.timeSynchronizationService
Automatic Time Synchronization
The time is synchronized automatically in the following situations:
- After an activation is created
- After getting an activation status
- After receiving any response encrypted with our End-To-End Encryption scheme
The time synchronization is reset automatically once your application transitions from the background to the foreground.
Manually Synchronize Time
Use the following code to synchronize the time manually:
val task = timeService.synchronizeTime(object: ITimeSynchronizationListener {
override fun onTimeSynchronizationSucceeded() {
// Synchronization succeeded
}
override fun onTimeSynchronizationFailed(t: Throwable) {
// Synchronization failed
}
})
Get Synchronized Time
To get the synchronized time, use the following code:
if (timeService.isTimeSynchronized) {
// get synchronized timestamp in milliseconds, since 1.1.1970
val timestamp = timeService.currentTime
} else {
// Time is not synchronized yet. If you call currentTime then
// the returned timestamp is similar to System.currentTimeMillis()
val timestamp = timeService.currentTime
}
The time service provides additional information about time, such as how precisely the time is synchronized with the server:
if (timeService.isTimeSynchronized) {
val precision = timeService.localTimeAdjustmentPrecision
println("Time is now synchronized with precision ${precision}")
}
The precision value represents a maximum absolute deviation of synchronized time against the actual time on the server. For example, a value 500 means that the time provided by the currentTime method may be 0.5 seconds ahead or behind the actual time on the server. If the precision is not sufficient for your purpose, for example, if you need to display a real-time countdown in your application, then try to synchronize the time manually. The precision basically depends on how quickly is the synchronization response received and processed from the server. A faster response results in higher precision.
Common SDK Tasks
Error Handling
The PowerAuth SDK uses the following types of exceptions:
PowerAuthMissingConfigException- is typically thrown immediately when thePowerAuthSDKinstance is initialized with an invalid configuration.FailedApiException- is typically returned to callbacks when an asynchronous HTTP request ends on error.ErrorResponseApiException- is typically returned to callbacks when an asynchronous HTTP request ends on an error and the error model object is present in the response.PowerAuthErrorException- typically covers all other erroneous situations. You can investigate a detailed reason for failure by getting the integer, from the set ofPowerAuthErrorCodesconstants.
Here’s an example of a typical error-handling procedure:
val t: Throwable // reported in asynchronous callback
when (t) {
is PowerAuthErrorException -> {
when (t.powerAuthErrorCode) {
PowerAuthErrorCodes.NETWORK_ERROR -> Log.d(TAG, "Error code for error with network connectivity or download")
PowerAuthErrorCodes.SIGNATURE_ERROR -> Log.d(TAG, "Error code for error in signature calculation")
PowerAuthErrorCodes.INVALID_ACTIVATION_STATE -> Log.d(TAG, "Error code for error that occurs when activation state is invalid")
PowerAuthErrorCodes.INVALID_ACTIVATION_DATA -> Log.d(TAG, "Error code for error that occurs when activation data is invalid")
PowerAuthErrorCodes.MISSING_ACTIVATION -> Log.d(TAG, "Error code for error that occurs when activation is required but missing")
PowerAuthErrorCodes.PENDING_ACTIVATION -> Log.d(TAG, "Error code for error that occurs when pending activation is present and work with completed activation is required")
PowerAuthErrorCodes.INVALID_ACTIVATION_CODE -> Log.d(TAG, "Error code for error that occurs when invalid activation code is provided.")
PowerAuthErrorCodes.BIOMETRY_CANCEL -> Log.d(TAG, "Error code for Biometry action cancel error")
PowerAuthErrorCodes.BIOMETRY_NOT_SUPPORTED -> Log.d(TAG, "The device or operating system doesn't support biometric authentication.")
PowerAuthErrorCodes.BIOMETRY_NOT_AVAILABLE -> Log.d(TAG, "The biometric authentication is temporarily unavailable.")
PowerAuthErrorCodes.BIOMETRY_NOT_RECOGNIZED -> Log.d(TAG, "The biometric authentication did not recognize the biometric image") // Reported only during biometric authentication setup
PowerAuthErrorCodes.BIOMETRY_NOT_ENROLLED -> Log.d(TAG, "The biometric authentication failed because there's no biometry enrolled")
PowerAuthErrorCodes.BIOMETRY_LOCKOUT -> Log.d(TAG, "The biometric authentication is locked out due to too many failed attempts.")
PowerAuthErrorCodes.OPERATION_CANCELED -> Log.d(TAG, "Error code for cancelled operations")
PowerAuthErrorCodes.ENCRYPTION_ERROR -> Log.d(TAG, "Error code for errors related to end-to-end encryption")
PowerAuthErrorCodes.INVALID_TOKEN -> Log.d(TAG, "Error code for errors related to token-based auth.")
PowerAuthErrorCodes.PROTOCOL_UPGRADE -> Log.d(TAG, "Error code for error that occurs when protocol upgrade fails at unrecoverable error.")
PowerAuthErrorCodes.PENDING_PROTOCOL_UPGRADE -> Log.d(TAG, "The operation is temporarily unavailable, due to pending protocol upgrade.")
PowerAuthErrorCodes.TIME_SYNCHRONIZATION -> Log.d(TAG, "Failed to synchronize time with the server.")
}
// Process additional information
val additionalInfo = error.additionalInformation
when (additionalInfo) {
is BiometricErrorInfo -> {
if (additionalInfo.isErrorPresentationRequired) {
//The application should display an error dialog after failed biometric authentication. This is relevant only
// if you disabled the biometric error dialog provided by PowerAuth mobile SDK.
}
}
}
}
is ErrorResponseApiException -> {
val errorResponse: Error? = t.errorResponse
val httpResponseStatusCode = t.responseCode
// Additional, optional objects assigned to the exception.
val jsonResponseObject: JsonObject = t.responseJson
val responseBodyString = t.responseBody
}
is FailedApiException -> {
val httpStatusCode = t.responseCode
// Additional, optional objects assigned to the exception.
val jsonResponseObject: JsonObject = t.responseJson
val responseBodyString = t.responseBody
}
}
Throwable t; // reported in asynchronous callback
if (t instanceof PowerAuthErrorException) {
switch (((PowerAuthErrorException) t).getPowerAuthErrorCode()) {
case PowerAuthErrorCodes.NETWORK_ERROR:
android.util.Log.d(TAG, "Error code for error with network connectivity or download"); break;
case PowerAuthErrorCodes.SIGNATURE_ERROR:
android.util.Log.d(TAG,"Error code for error in signature calculation"); break;
case PowerAuthErrorCodes.INVALID_ACTIVATION_STATE:
android.util.Log.d(TAG,"Error code for error that occurs when activation state is invalid"); break;
case PowerAuthErrorCodes.INVALID_ACTIVATION_DATA:
android.util.Log.d(TAG,"Error code for error that occurs when activation data is invalid"); break;
case PowerAuthErrorCodes.MISSING_ACTIVATION:
android.util.Log.d(TAG,"Error code for error that occurs when activation is required but missing"); break;
case PowerAuthErrorCodes.PENDING_ACTIVATION:
android.util.Log.d(TAG,"Error code for error that occurs when pending activation is present and work with completed activation is required"); break;
case PowerAuthErrorCodes.INVALID_ACTIVATION_CODE:
android.util.Log.d(TAG,"Error code for error that occurs when invalid activation code is provided."); break;
case PowerAuthErrorCodes.BIOMETRY_CANCEL:
android.util.Log.d(TAG,"Error code for Biometry action cancel error"); break;
case PowerAuthErrorCodes.BIOMETRY_NOT_SUPPORTED:
android.util.Log.d(TAG,"The device or operating system doesn't support biometric authentication."); break;
case PowerAuthErrorCodes.BIOMETRY_NOT_AVAILABLE:
android.util.Log.d(TAG,"The biometric authentication is temporarily unavailable."); break;
case PowerAuthErrorCodes.BIOMETRY_NOT_RECOGNIZED:
// Reported only during biometric authentication setup
android.util.Log.d(TAG,"The biometric authentication did not recognize the biometric image (fingerprint, face, etc...)"); break;
case PowerAuthErrorCodes.BIOMETRY_NOT_ENROLLED:
android.util.Log.d(TAG,"The biometric authentication failed because there's no biometry enrolled"); break;
case PowerAuthErrorCodes.BIOMETRY_LOCKOUT:
android.util.Log.d(TAG,"The biometric authentication is locked out due to too many failed attempts."); break;
case PowerAuthErrorCodes.OPERATION_CANCELED:
android.util.Log.d(TAG,"Error code for cancelled operations"); break;
case PowerAuthErrorCodes.ENCRYPTION_ERROR:
android.util.Log.d(TAG,"Error code for errors related to end-to-end encryption"); break;
case PowerAuthErrorCodes.INVALID_TOKEN:
android.util.Log.d(TAG,"Error code for errors related to token-based auth."); break;
case PowerAuthErrorCodes.PROTOCOL_UPGRADE:
android.util.Log.d(TAG,"Error code for error that occurs when protocol upgrade fails at unrecoverable error."); break;
case PowerAuthErrorCodes.PENDING_PROTOCOL_UPGRADE:
android.util.Log.d(TAG,"The operation is temporarily unavailable, due to pending protocol upgrade."); break;
case PowerAuthErrorCodes.TIME_SYNCHRONIZATION:
android.util.Log.d(TAG,"Failed to synchronize time with the server."); break;
}
// Process additional information
if (exception.getAdditionalInformation() instanceof BiometricErrorInfo) {
BiometricErrorInfo biometricErrorInfo = (BiometricErrorInfo) exception.getAdditionalInformation();
if (biometricErrorInfo.isErrorPresentationRequired()) {
//The application should display an error dialog after failed biometric authentication. This is relevant only
// if you disabled the biometric error dialog provided by PowerAuth mobile SDK.
}
}
} else if (t instanceof ErrorResponseApiException) {
ErrorResponseApiException exception = (ErrorResponseApiException) t;
Error errorResponse = exception.getErrorResponse();
int httpResponseStatusCode = exception.getResponseCode();
// Additional, optional objects assigned to the exception.
JsonObject jsonResponseObject = exception.getResponseJson();
String responseBodyString = exception.getResponseBody();
} else if (t instanceof FailedApiException) {
FailedApiException exception = (FailedApiException) t;
int httpStatusCode = exception.getResponseCode();
// Additional, optional objects assigned to the exception.
JsonObject jsonResponseObject = exception.getResponseJson();
String responseBodyString = exception.getResponseBody();
}
Note that you typically don’t need to handle all error codes reported in the PowerAuthErrorException, or report all those situations to the user. Most of the codes are informational and help the developers properly integrate SDK into the application. A good example is INVALID_ACTIVATION_STATE, which typically means that your application’s logic is broken and you’re using PowerAuthSDK in an unexpected way.
Here’s the list of important error codes, which the application should properly handle:
BIOMETRY_CANCELis reported when the user cancels the biometric authentication dialogPROTOCOL_UPGRADEis reported when SDK fails to upgrade itself to a newer protocol version. The code may be reported fromPowerAuthSDK.fetchActivationStatusWithCallback(). This is an unrecoverable error resulting in the broken activation on the device, so the best situation is to inform the user about the situation and remove the activation locally.PENDING_PROTOCOL_UPGRADEis reported when the requested SDK operation cannot be completed due to a pending PowerAuth protocol upgrade. You can retry the operation later. The code is typically reported in situations when SDK is performing protocol upgrade in the background (as a part of activation status fetch), and the application wants to calculate the PowerAuth signature in parallel operation. Such kind of concurrency is forbidden since SDK version1.0.0
Working with Invalid SSL Certificates
Sometimes, you may need to develop or test your application against a service that runs over HTTPS protocol with an invalid (self-signed) SSL certificate. By default, the HTTP client used in PowerAuth SDK communication validates the certificate. To disable the certificate validation, use a PowerAuthSDK initializer with a custom client configuration to initialize your PowerAuth SDK instance, like so:
// Set `HttpClientSslNoValidationStrategy as the default client SSL certificate validation strategy
val clientConfiguration = PowerAuthClientConfiguration.Builder()
.clientValidationStrategy(HttpClientSslNoValidationStrategy())
.build()
// Set `HttpClientSslNoValidationStrategy as the default client SSL certificate validation strategy
final PowerAuthClientConfiguration clientConfiguration = new PowerAuthClientConfiguration.Builder()
.clientValidationStrategy(new HttpClientSslNoValidationStrategy())
.build();
Be aware, that using this option will lead to the use of an unsafe implementation of HostnameVerifier and X509TrustManager SSL client validation. This is useful for debug/testing purposes only, e.g. when an untrusted self-signed SSL certificate is used on the server side.
It’s strictly recommended to use this option only in debug flavors of your application. Deploying to production may cause a “Security alert” in the Google Developer Console. Please see this and this Google Help Center articles for more details. Beginning 1 March 2017, Google Play will block the publishing of any new apps or updates that use such unsafe implementation of HostnameVerifier.
How to solve this problem for debug/production flavors in the Gradle build script:
- Define the boolean type
buildConfigFieldin the flavor configuration.productFlavors { production { buildConfigField 'boolean', 'TRUST_ALL_SSL_HOSTS', 'false' } debug { buildConfigField 'boolean', 'TRUST_ALL_SSL_HOSTS', 'true' } } - In code use this conditional initialization for the
PowerAuthClientConfiguration.Builderbuilder.
val clientBuilder = PowerAuthClientConfiguration.Builder()
if (BuildConfig.TRUST_ALL_SSL_HOSTS) {
clientBuilder.clientValidationStrategy(HttpClientSslNoValidationStrategy())
}
PowerAuthClientConfiguration.Builder clientBuilder = new PowerAuthClientConfiguration.Builder();
if (BuildConfig.TRUST_ALL_SSL_HOSTS) {
clientBuilder.clientValidationStrategy(new HttpClientSslNoValidationStrategy());
}
- Set
minifyEnabledto true for release buildType to enable code shrinking with ProGuard.
Debugging
The debug log is by default turned off. To turn it on, use the following code:
PowerAuthLog.setEnabled(true)
PowerAuthLog.setEnabled(true);
To turn on an even more detailed log, use the following code:
PowerAuthLog.setVerbose(true)
PowerAuthLog.setVerbose(true);
Note that it’s highly recommended to turn on this feature only for the DEBUG build of your application. For example:
if (BuildConfig.DEBUG) {
PowerAuthLog.setEnabled(true)
}
if (BuildConfig.DEBUG) {
PowerAuthLog.setEnabled(true);
}
Additional Features
PowerAuth SDK for Android contains multiple additional features that are useful for mobile apps.
Obtaining User’s Claims
If supported by the server, the PowerAuth mobile SDK can provide additional information asserted about a person associated with an activation. This information can be obtained either during the activation process or at a later time.
Here is an example of how to process user information during activation:
powerAuthSDK.createActivation(activation, object : ICreateActivationListener {
override fun onActivationCreateSucceed(result: CreateActivationResult) {
if (result.userInfo != null) {
// User information received.
// At this moment, the object is also available at
// powerAuthSDK.lastFetchedUserInfo
}
}
override fun onActivationCreateFailed(t: Throwable) {
// Error handling
}
})
To fetch the user information at a later time, use the following code:
val userInfo = powerAuthSDK.lastFetchedUserInfo
if (userInfo != null) {
// User information is already available
} else {
powerAuthSDK.fetchUserInfo(context, object : IUserInfoListener {
override fun onUserInfoSucceed(userInfo: UserInfo) {
// User information received
}
override fun onUserInfoFailed(t: Throwable) {
// Error handling
}
})
}
The obtained UserInfo object contains the following properties:
| Property | Type | Description |
|---|---|---|
subject |
String |
The user’s identifier |
name |
String |
The full name of the user |
givenName |
String |
The given or first name of the user |
familyName |
String |
The surname(s) or last name(s) of the user |
middleName |
String |
The middle name of the user |
nickname |
String |
The casual name of the user |
preferredUsername |
String |
The username by which the user wants to be referred to at the application |
profileUrl |
String |
The URL of the profile page for the user |
pictureUrl |
String |
The URL of the profile picture for the user |
websiteUrl |
String |
The URL of the user’s web page or blog |
email |
String |
The user’s preferred email address |
isEmailVerified |
Boolean |
True if the user’s email address has been verified, else false1 |
phoneNumber |
String |
The user’s preferred telephone number2 |
isPhoneNumberVerified |
Boolean |
True if the user’s telephone number has been verified, else false1 |
gender |
String |
The user’s gender |
birthdate |
Date |
The user’s birthday |
zoneInfo |
String |
The user’s time zone, e.g. Europe/Paris or America/Los_Angeles |
locale |
String |
The end-users locale, represented as a BCP47 language tag3 |
address |
UserAddress |
The user’s preferred postal address |
updatedAt |
Date |
The time the user’s information was last updated |
allClaims |
Map<String, Any> |
The full collection of claims received from the server |
If the address is provided, then UserAddress contains the following properties:
| Property | Type | Description |
|---|---|---|
formatted |
String |
The full mailing address, with multiple lines if necessary |
street |
String |
The street address component, which may include house number, street name, post office box, and other multi-line information |
locality |
String |
City or locality component |
region |
String |
State, province, prefecture or region component |
postalCode |
String |
Zip code or postal code component |
country |
String |
Country name component |
allClaims |
Map<String, Any> |
Full collection of claims received from the server |
Notes:
- Value is false also when a claim is not present in the
allClaimsdictionary- Phone number is typically in E.164 format, for example
+1 (425) 555-1212or+56 (2) 687 2400- This is typically an ISO 639-1 Alpha-2 language code in lowercase and an ISO 3166-1 Alpha-2 country code in uppercase, separated by a dash. For example,
en-USorfr-CA
Be aware that all properties in the UserInfo and UserAddress objects are optional and the availability of information depends on actual implementation on the server.
Password Strength Indicator
Choosing a weak passphrase in applications with high-security demands can be potentially dangerous. You can use our Wultra Passphrase Meter library to estimate the strength of the passphrase and warn the user when he tries to use such a passphrase in your application.
Debug Build Detection
It is sometimes useful to switch PowerAuth SDK to a DEBUG build configuration to get more logs from the library. The DEBUG build is usually helpful during application development, but on the other hand, it’s highly unwanted in production applications. For this purpose, the PowerAuthSDK.hasDebugFeatures() method provides information on whether the PowerAuth JNI library was compiled in the DEBUG configuration. It is a good practice to check this flag and crash the process when the production application is linked against the DEBUG PowerAuth:
if (!BuildConfig.DEBUG) {
// You can also check your production build configuration
if (powerAuthSDK.hasDebugFeatures()) {
throw RuntimeException("Production app with DEBUG PowerAuth")
}
}
if (!BuildConfig.DEBUG) {
// You can also check your production build configuration
if (powerAuthSDK.hasDebugFeatures()) {
throw new RuntimeException("Production app with DEBUG PowerAuth");
}
}
Request Interceptors
The PowerAuthClientConfiguration can contain multiple request interceptor objects, allowing you to adjust all HTTP requests created by SDK, before execution. Currently, you can use the following two classes:
BasicHttpAuthenticationRequestInterceptorto add a basic HTTP authentication header to all requestsCustomHeaderRequestInterceptorto add a custom HTTP header to all requests
For example:
val clientConfiguration = PowerAuthClientConfiguration.Builder()
.requestInterceptor(BasicHttpAuthenticationRequestInterceptor("gateway-user", "gateway-password"))
.requestInterceptor(CustomHeaderRequestInterceptor("X-CustomHeader", "123456"))
.build()
final PowerAuthClientConfiguration clientConfiguration = new PowerAuthClientConfiguration.Builder()
.requestInterceptor(new BasicHttpAuthenticationRequestInterceptor("gateway-user", "gateway-password"))
.requestInterceptor(new CustomHeaderRequestInterceptor("X-CustomHeader", "123456"))
.build();
We don’t recommend implementing the HttpRequestInterceptor interface on your own. The interface allows you to tweak the requests created in the PowerAuthSDK but also gives you an opportunity to break things. So, rather than create your own interceptor, try to contact us and describe what’s your problem with the networking in the PowerAuth SDK. Also, keep in mind that the interface may change in the future. We can guarantee the API stability of public classes implementing this interface, but not the stability of the interface itself.
Custom User-Agent
The PowerAuthClientConfiguration contains the userAgent property that allows you to set a custom value for the “User-Agent” HTTP request header for all requests initiated by the library:
val clientConfiguration = PowerAuthClientConfiguration.Builder()
.userAgent("MyApp/1.0.0")
.build()
final PowerAuthClientConfiguration clientConfiguration = new PowerAuthClientConfiguration.Builder()
.userAgent("MyApp/1.0.0")
.build();
The default value of the property is composed as “APP-PACKAGE/APP-PACKAGE-VERSION PowerAuth2/PA-VERSION (OS/OS-VERSION, DEVICE-INFO)”, for example: “com.test.app/1.0 PowerAuth2/1.7.0 (Android 11.0.0, SM-A525F)”.
If you set "" (empty string) to the userAgent property, then the default “User-Agent” provided by the operating system will be used.