Refactor BiometricHelper

RomanTsisyk · Nov 30, 2024 · a061f9a · a061f9a
1 parent 5889085
commit a061f9a
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Showing 2 changed files with 36 additions and 17 deletions.
diff --git a/cryptolib/src/main/java/io/github/romantsisyk/cryptolib/biometrics/BiometricHelper.kt b/cryptolib/src/main/java/io/github/romantsisyk/cryptolib/biometrics/BiometricHelper.kt
@@ -1,16 +1,22 @@
-package io.github.romantsisyk.cryptolib.biometrics
-
-
-import io.github.romantsisyk.cryptolib.crypto.keymanagement.KeyHelper
-import javax.crypto.Cipher
-import io.github.romantsisyk.cryptolib.crypto.aes.AESEncryption
 import android.content.Context
-import android.widget.Toast
 import androidx.biometric.BiometricPrompt
 import androidx.fragment.app.FragmentActivity
+import io.github.romantsisyk.cryptolib.crypto.aes.AESEncryption
+import io.github.romantsisyk.cryptolib.crypto.keymanagement.KeyHelper
+import javax.crypto.Cipher
 
 class BiometricHelper(private val context: Context) {
 
+    /**
+     * Authenticates the user using biometrics and optionally decrypts the provided encrypted data.
+     * @param activity The activity where the biometric prompt will be displayed.
+     * @param encryptedData Data to be decrypted upon successful authentication.
+     * @param title The title displayed on the biometric prompt.
+     * @param description The description displayed on the biometric prompt.
+     * @param onSuccess Callback to handle the decrypted data.
+     * @param onError Callback to handle errors during authentication or decryption.
+     * @param onAuthenticationError Callback to handle authentication-specific errors.
+     */
     fun authenticate(
         activity: FragmentActivity,
         title: String,
@@ -35,6 +41,7 @@ class BiometricHelper(private val context: Context) {
                 override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
                     super.onAuthenticationSucceeded(result)
                     try {
+                        // Decrypt the data using the authenticated cipher
                         val decryptedData = result.cryptoObject?.cipher?.let {
                             AESEncryption.decrypt(
                                 encryptedData.toString(Charsets.UTF_8),
@@ -54,14 +61,11 @@ class BiometricHelper(private val context: Context) {
                 override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
                     super.onAuthenticationError(errorCode, errString)
                     onAuthenticationError(errorCode, errString)
-                    onError(Exception("Authentication error [$errorCode]: $errString"))
-
                 }
 
                 override fun onAuthenticationFailed() {
                     super.onAuthenticationFailed()
-                    Toast.makeText(context, "Authentication failed. Try again.", Toast.LENGTH_SHORT)
-                        .show()
+                    onError(Exception("Authentication failed"))
                 }
             }
         )
@@ -72,14 +76,29 @@ class BiometricHelper(private val context: Context) {
         biometricPrompt.authenticate(promptInfo, cryptoObject)
     }
 
+    /**
+     * Initializes a Cipher object for decryption.
+     * @return A Cipher initialized with a secret key.
+     * @throws IllegalStateException if initialization fails.
+     */
     private fun getCipher(): Cipher {
         return try {
-            val secretKey = KeyHelper.getKey() // Retrieve the secure key
-            val cipher = KeyHelper.getCipherInstance() // Get Cipher instance
+            val secretKey = KeyHelper.getKey() // Retrieve the secure key from KeyHelper
+            val cipher = Cipher.getInstance("AES/GCM/NoPadding")
             cipher.init(Cipher.DECRYPT_MODE, secretKey)
             cipher
         } catch (e: Exception) {
             throw IllegalStateException("Failed to initialize Cipher", e)
         }
     }
-}
+
+    /**
+     * Decrypts the provided data using the Cipher.
+     * @param cipher The Cipher used for decryption.
+     * @param encryptedData The encrypted data to decrypt.
+     * @return The decrypted data as a ByteArray.
+     */
+    private fun decryptData(cipher: Cipher, encryptedData: ByteArray): ByteArray {
+        return cipher.doFinal(encryptedData)
+    }
+}
diff --git a/cryptolib/src/main/java/io/github/romantsisyk/cryptolib/crypto/manager/CryptoManager.kt b/cryptolib/src/main/java/io/github/romantsisyk/cryptolib/crypto/manager/CryptoManager.kt
@@ -1,8 +1,8 @@
 package io.github.romantsisyk.cryptolib.crypto.manager
 
+import BiometricHelper
 import android.app.Activity
 import androidx.fragment.app.FragmentActivity
-import io.github.romantsisyk.cryptolib.biometrics.BiometricHelper
 import io.github.romantsisyk.cryptolib.crypto.config.CryptoConfig
 import io.github.romantsisyk.cryptolib.crypto.aes.AESEncryption
 import io.github.romantsisyk.cryptolib.crypto.keymanagement.KeyHelper
@@ -103,11 +103,11 @@ object CryptoManager {
                     onAuthenticationError = { errorCode, errString ->
                         onFailure(
                             AuthenticationException(
-                                 "Authentication error [$errorCode]: $errString"
+                                "Authentication error [$errorCode]: $errString"
                             )
                         )
                     },
-                    onError = {exception ->  println("Error: ${exception.message}")}
+                    onError = { exception -> println("Error: ${exception.message}") }
                 )
             } else {
                 onAuthenticated(secretKey)