Implementing Biometric Authentication

import android.hardware.biometrics.BiometricManager
import android.os.Build

val biometricManager = BiometricManager.from(context)
val canAuthenticate = biometricManager.canAuthenticate()

when (canAuthenticate) {
    BiometricManager.BIOMETRIC_SUCCESS -> {
        // Biometric authentication is available
    }
    BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE -> {
        // No biometric hardware available
    }
    BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE -> {
        // Biometric hardware is unavailable
    }
    BiometricManager.BIOMETRIC_ERROR_UNSUPPORTED -> {
        // Biometric authentication is not supported
    }
    BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED -> {
        // No biometrics enrolled
    }
}

import android.hardware.biometrics.BiometricPrompt
import android.os.CancellationSignal
import androidx.fragment.app.Fragment

class BiometricAuthFragment : Fragment() {
    private lateinit var biometricPrompt: BiometricPrompt
    private lateinit var promptInfo: BiometricPrompt.PromptInfo

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        biometricPrompt = BiometricPrompt(this, object : BiometricPrompt.AuthenticationCallback() {
            override fun onAuthenticationSucceeded(
                result: BiometricPrompt.AuthenticationResult
            ) {
                // Handle successful authentication
                handleSuccessfulAuth()
            }

            override fun onAuthenticationFailed() {
                // Handle failed authentication
                handleFailedAuth()
            }

            override fun onAuthenticationError(
                errorCode: Int,
                errString: CharSequence
            ) {
                // Handle authentication error
                handleError(errorCode, errString)
            }
        })

        promptInfo = BiometricPrompt.PromptInfo.Builder()
            .setTitle("Biometric Authentication")
            .setSubtitle("Scan your fingerprint or face")
            .setDescription("Use your biometric credentials to authenticate")
            .setConfirmationRequired(true)
            .setNegativeButtonText("Use Password")
            .build()
    }

    private fun handleSuccessfulAuth() {
        // Proceed with authenticated action
    }

    private fun handleFailedAuth() {
        // Retry or show error
    }

    private fun handleError(errorCode: Int, errString: CharSequence) {
        // Handle error appropriately
    }
}

val promptInfo = BiometricPrompt.PromptInfo.Builder()
    .setTitle("Authenticate to access your account")
    .setSubtitle("Touch fingerprint sensor")
    .setDescription("Use your fingerprint to unlock")
    .setNegativeButtonText("Cancel")
    .build()

class MainActivity : AppCompatActivity() {
    private lateinit var biometricPrompt: BiometricPrompt
    private lateinit var promptInfo: BiometricPrompt.PromptInfo

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val executor = ContextCompat.getMainExecutor(this)
        biometricPrompt = BiometricPrompt(this, executor, object : BiometricPrompt.AuthenticationCallback() {
            override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
                // Handle successful authentication
                Toast.makeText(this@MainActivity, "Authentication successful", Toast.LENGTH_SHORT).show()
            }

            override fun onAuthenticationFailed() {
                // Handle failed authentication
                Toast.makeText(this@MainActivity, "Authentication failed", Toast.LENGTH_SHORT).show()
            }
        })

        promptInfo = BiometricPrompt.PromptInfo.Builder()
            .setTitle("Sign in with fingerprint")
            .setSubtitle("Use your fingerprint to authenticate")
            .setNegativeButtonText("Cancel")
            .build()
    }

    private fun authenticateUser() {
        biometricPrompt.authenticate(promptInfo)
    }
}

class AuthenticationCallback : BiometricPrompt.AuthenticationCallback() {
    override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
        val cryptoObject = result.cryptoObject
        // Process successful authentication
        handleSuccessfulAuth(cryptoObject)
    }

    override fun onAuthenticationFailed() {
        // Handle failed authentication
        showFailureMessage()
    }

    override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
        // Handle authentication error
        handleError(errorCode, errString)
    }
}

val cryptoObject = BiometricPrompt.CryptoObject(cipher)

val biometricPrompt = BiometricPrompt(this, ContextCompat.getMainExecutor(this),
    object : BiometricPrompt.AuthenticationCallback() {
        override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
            when (errorCode) {
                BiometricPrompt.ERROR_HW_UNAVAILABLE -> {
                    // Handle hardware unavailable
                    Toast.makeText(this@MainActivity, "Biometric hardware not available", Toast.LENGTH_LONG).show()
                }
                BiometricPrompt.ERROR_LOCKOUT -> {
                    // Handle lockout
                    Toast.makeText(this@MainActivity, "Too many failed attempts. Try again later.", Toast.LENGTH_LONG).show()
                }
                else -> {
                    // Handle other errors
                    Toast.makeText(this@MainActivity, "Authentication error: $errString", Toast.LENGTH_LONG).show()
                }
            }
        }

        override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
            // Handle successful authentication
            Toast.makeText(this@MainActivity, "Authentication successful", Toast.LENGTH_SHORT).show()
        }

        override fun onAuthenticationFailed() {
            // Handle failed authentication
            Toast.makeText(this@MainActivity, "Authentication failed", Toast.LENGTH_SHORT).show()
        }
    })

val promptInfo = BiometricPrompt.PromptInfo.Builder()
    .setTitle("Authenticate with Device Credential")
    .setSubtitle("Use your device PIN or password")
    .setAllowedAuthenticators(BiometricManager.Authenticators.DEVICE_CREDENTIAL)
    .build()

val biometricPrompt = BiometricPrompt(this, object : BiometricPrompt.AuthenticationCallback() {
    override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
        // Handle successful authentication
    }

    override fun onAuthenticationFailed() {
        // Handle failed authentication
    }
})

biometricPrompt.authenticate(promptInfo)

import androidx.biometric.BiometricManager
import androidx.biometric.BiometricPrompt
import android.content.Context
import android.os.CancellationSignal

class BiometricEnrollmentHelper(private val context: Context) {

    fun startEnrollment() {
        val biometricManager = BiometricManager.from(context)
        val enrollmentStatus = biometricManager.canAuthenticate()

        when (enrollmentStatus) {
            BiometricManager.BIOMETRIC_SUCCESS -> {
                // Start enrollment process
                val promptInfo = BiometricPrompt.PromptInfo.Builder()
                    .setTitle("Enroll Fingerprint")
                    .setSubtitle("Scan your fingerprint to enroll")
                    .setConfirmationRequired(false)
                    .build()

                val biometricPrompt = BiometricPrompt(this, object : BiometricPrompt.AuthenticationCallback() {
                    override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
                        // Enrollment successful
                    }

                    override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
                        // Handle error
                    }
                })

                biometricPrompt.authenticate(promptInfo, CancellationSignal())
            }
            else -> {
                // Handle unsupported or unavailable biometric
            }
        }
    }
}

class BiometricAuthTest {
    @Test
    fun testBiometricAuthenticationSuccess() {
        val activity = Robolectric.buildActivity(MainActivity::class.java).create().get()
        val biometricPrompt = BiometricPrompt.Builder(activity)
            .setTitle("Authenticate")
            .setSubtitle("Scan your fingerprint")
            .setDescription("Touch sensor to authenticate")
            .build()

        val callback = object : BiometricPrompt.AuthenticationCallback() {
            override fun onAuthenticationSucceeded(
                result: BiometricPrompt.AuthenticationResult
            ) {
                assertTrue("Authentication should succeed", true)
            }

            override fun onAuthenticationFailed() {
                fail("Authentication failed unexpectedly")
            }
        }

        biometricPrompt.authenticate(
            CancellationSignal(),
            ContextCompat.getMainExecutor(activity),
            callback
        )
    }
}