Basierend auf einer möglichst geringen Änderung des Originalcodes wur…

…den die folgenden zwei Punkte verbessert:

Optimieren Sie die Leistung und reduzieren Sie den durch unnötigen Code verursachten Leistungsaufwand.
Verbesserte Speichersicherheit, um zu verhindern, dass Ressourcen nicht sofort zurückgefordert werden.

core/src/main/java/de/raphaelebner/roomdatabasebackup/core/AESEncryptionHelper.kt

@@ -45,11 +45,8 @@ class AESEncryptionHelper {
      */
     @Throws(Exception::class)
     fun readFile(file: File): ByteArray {
-        val fileContents = file.readBytes()
-        val inputBuffer = BufferedInputStream(FileInputStream(file))
-        inputBuffer.read(fileContents)
-        inputBuffer.close()
-        return fileContents
+        // read file to ByteArray
+        return file.readBytes()
     }
 
     /**
@@ -59,10 +56,12 @@ class AESEncryptionHelper {
      */
     @Throws(Exception::class)
     fun saveFile(fileData: ByteArray, file: File) {
-        val bos = BufferedOutputStream(FileOutputStream(file, false))
-        bos.write(fileData)
-        bos.flush()
-        bos.close()
+        // Even if an exception occurs in the use block, the resource will be closed correctly,
+        // which helps prevent resource leaks and improve application stability and performance.
+        BufferedOutputStream(FileOutputStream(file, false)).use { bos ->
+            bos.write(fileData)
+            bos.flush()
+        }
     }
 
     /**
@@ -84,15 +83,8 @@ class AESEncryptionHelper {
             val charset = ('a'..'z') + ('A'..'Z') + ('1'..'9')
             password = (1..stringLength).map { charset.random() }.joinToString("")
 
-            val secretKey = generateSecretKey(password, iv)
-            // the key can be saved plain, because i am using EncryptedSharedPreferences
-            val editor = sharedPref.edit()
-            editor.putString(BACKUP_SECRET_KEY, password)
-            // I use .commit because when using .apply the needed app restart is faster then apply
-            // and the preferences wont be saved
-            editor.commit()
-
-            return secretKey
+            // save key to shared pref
+            sharedPref.edit().putString(BACKUP_SECRET_KEY, password).commit()
         }
 
         // generate secretKey, and return it

core/src/main/java/de/raphaelebner/roomdatabasebackup/core/AESEncryptionManager.kt

@@ -22,6 +22,10 @@ class AESEncryptionManager {
 
     private val aesEncryptionHelper = AESEncryptionHelper()
 
+    // Creating a new Cipher instance for each encryption and decryption operation may cause performance degradation because creating a Cipher instance is an expensive operation.
+    // Optimize this problem by creating a Cipher instance at the class level and reusing it when needed.
+    private val cipher = Cipher.getInstance("AES/GCM/NoPadding")
+
     /**
      * This method will encrypt the given data
      * @param sharedPref : the sharedPref, to fetch the key
@@ -50,7 +54,6 @@ class AESEncryptionManager {
         val secretKey = if (encryptPassword != null) { aesEncryptionHelper.getSecretKeyWithCustomPw(encryptPassword, iv)
         } else aesEncryptionHelper.getSecretKey(sharedPref, iv)
 
-        val cipher = Cipher.getInstance("AES/GCM/NoPadding")
         val parameterSpec = GCMParameterSpec(128, iv)
 
         //Encryption mode on!
@@ -84,24 +87,21 @@ class AESEncryptionManager {
     )
     fun decryptData(sharedPref: SharedPreferences, encryptPassword: String?, encryptedData: ByteArray): ByteArray {
 
-
-        //Wrap the data into a byte buffer to ease the reading process
-        val byteBuffer = ByteBuffer.wrap(encryptedData)
-        val noonceSize = byteBuffer.int
+        // There is no need to convert to ByteBuffer, which will cause additional performance overhead.
+        val noonceSize = encryptedData[0].toInt()
 
         //Make sure that the file was encrypted properly
         require(!(noonceSize < 12 || noonceSize >= 16)) { "Nonce size is incorrect. Make sure that the incoming data is an AES encrypted file." }
-        val iv = ByteArray(noonceSize)
-        byteBuffer[iv]
+
+        val iv = encryptedData.sliceArray(1 until noonceSize+1)
 
         //Prepare your key/password
         val secretKey = if (encryptPassword != null) { aesEncryptionHelper.getSecretKeyWithCustomPw(encryptPassword, iv)
         } else aesEncryptionHelper.getSecretKey(sharedPref, iv)
 
         //get the rest of encrypted data
-        val cipherBytes = ByteArray(byteBuffer.remaining())
-        byteBuffer[cipherBytes]
-        val cipher = Cipher.getInstance("AES/GCM/NoPadding")
+        val cipherBytes = encryptedData.sliceArray(noonceSize+1 until encryptedData.size)
+
         val parameterSpec = GCMParameterSpec(128, iv)
 
         //Encryption mode on!

core/src/main/java/de/raphaelebner/roomdatabasebackup/core/RoomBackup.kt

@@ -386,10 +386,10 @@ class RoomBackup(var context: Context) {
         roomDatabase = null
         if (backupIsEncrypted) {
             val encryptedBytes = encryptBackup() ?: return
-            val bos = BufferedOutputStream(FileOutputStream(destination, false))
-            bos.write(encryptedBytes)
-            bos.flush()
-            bos.close()
+            BufferedOutputStream(FileOutputStream(destination, false)).use { bos ->
+                bos.write(encryptedBytes)
+                bos.flush()
+            }
         } else {
             // Copy current database to save location (/files dir)
             copy(DATABASE_FILE, destination)
@@ -577,10 +577,10 @@ class RoomBackup(var context: Context) {
         if (backupIsEncrypted) {
             copy(source, TEMP_BACKUP_FILE)
             val decryptedBytes = decryptBackup() ?: return
-            val bos = BufferedOutputStream(FileOutputStream(DATABASE_FILE, false))
-            bos.write(decryptedBytes)
-            bos.flush()
-            bos.close()
+            BufferedOutputStream(FileOutputStream(DATABASE_FILE, false)).use { bos ->
+                bos.write(decryptedBytes)
+                bos.flush()
+            }
         } else {
             if (fileExtension == "aes") {
                 if (enableLogDebug)
@@ -622,10 +622,10 @@ class RoomBackup(var context: Context) {
             roomDatabase!!.close()
             roomDatabase = null
 
-            val bos = BufferedOutputStream(FileOutputStream(DATABASE_FILE, false))
-            bos.write(decryptedBytes)
-            bos.flush()
-            bos.close()
+            BufferedOutputStream(FileOutputStream(DATABASE_FILE, false)).use { bos ->
+                bos.write(decryptedBytes)
+                bos.flush()
+            }
         } else {
             // Close the database
             roomDatabase!!.close()