[Precogs Alert] Cryptographic Weakness (Insecure Key Derivation and ECB Mode) detected (CWE-327, CWE-326, Risk: High)

File Encryption&Decryption/FileEncryptionDecryption.java

@@ -5,14 +5,32 @@
 import java.nio.file.Paths;
 import java.security.Key;
 
+import javax.crypto.Cipher;
+import javax.crypto.SecretKey;
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.PBEKeySpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.io.BufferedReader;
+import java.io.FileOutputStream;
+import java.io.InputStreamReader;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.security.SecureRandom;
+import java.security.spec.KeySpec;
+import java.util.Base64;
+
 public class FileEncryptionDecryption {
 
-    private static final String AES_ALGORITHM = "AES";
+    private static final String AES_ALGORITHM = "AES/CBC/PKCS5Padding"; // FIX: Use CBC mode with PKCS5Padding
     private static final String ENCRYPTED_FILE_EXTENSION = ".enc";
+    private static final int IV_SIZE = 16; // 128 bits
+    private static final int SALT_SIZE = 16; // 128 bits
+    private static final int KEY_SIZE = 256; // bits
+    private static final int PBKDF2_ITERATIONS = 65536;
 
     public static void RunFileEncryptionDecryption(String[] args) {
         try {
-            // Read user input
             BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
             System.out.print("Enter file path: ");
             String filePath = reader.readLine();
@@ -40,36 +58,61 @@ public static void RunFileEncryptionDecryption(String[] args) {
     private static void encryptFile(String filePath, String encryptionKey) throws Exception {
         byte[] fileContent = Files.readAllBytes(Paths.get(filePath));
 
-        Key key = generateKey(encryptionKey);
+        // FIX: Generate random salt and IV
+        SecureRandom random = new SecureRandom();
+        byte[] salt = new byte[SALT_SIZE];
+        random.nextBytes(salt);
+        byte[] iv = new byte[IV_SIZE];
+        random.nextBytes(iv);
+
+        SecretKey key = generateKey(encryptionKey, salt);
         Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
-        cipher.init(Cipher.ENCRYPT_MODE, key);
+        cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(iv));
 
         byte[] encryptedContent = cipher.doFinal(fileContent);
 
+        // FIX: Prepend salt and IV to the encrypted file (Base64 encoded for safety)
         String encryptedFilePath = filePath + ENCRYPTED_FILE_EXTENSION;
-        FileOutputStream outputStream = new FileOutputStream(encryptedFilePath);
-        outputStream.write(encryptedContent);
-        outputStream.close();
+        try (FileOutputStream outputStream = new FileOutputStream(encryptedFilePath)) {
+            outputStream.write(salt);
+            outputStream.write(iv);
+            outputStream.write(encryptedContent);
+        }
     }
 
     private static void decryptFile(String filePath, String encryptionKey) throws Exception {
-        byte[] encryptedContent = Files.readAllBytes(Paths.get(filePath));
-
-        Key key = generateKey(encryptionKey);
+        byte[] fileData = Files.readAllBytes(Paths.get(filePath));
+        if (fileData.length < SALT_SIZE + IV_SIZE) {
+            throw new IllegalArgumentException("File too short to contain salt and IV");
+        }
+        // FIX: Extract salt and IV
+        byte[] salt = new byte[SALT_SIZE];
+        byte[] iv = new byte[IV_SIZE];
+        System.arraycopy(fileData, 0, salt, 0, SALT_SIZE);
+        System.arraycopy(fileData, SALT_SIZE, iv, 0, IV_SIZE);
+        byte[] encryptedContent = new byte[fileData.length - SALT_SIZE - IV_SIZE];
+        System.arraycopy(fileData, SALT_SIZE + IV_SIZE, encryptedContent, 0, encryptedContent.length);
+
+        SecretKey key = generateKey(encryptionKey, salt);
         Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
-        cipher.init(Cipher.DECRYPT_MODE, key);
+        cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
 
         byte[] decryptedContent = cipher.doFinal(encryptedContent);
 
         String decryptedFilePath = filePath.replace(ENCRYPTED_FILE_EXTENSION, "");
-        FileOutputStream outputStream = new FileOutputStream(decryptedFilePath);
-        outputStream.write(decryptedContent);
-        outputStream.close();
+        try (FileOutputStream outputStream = new FileOutputStream(decryptedFilePath)) {
+            outputStream.write(decryptedContent);
+        }
     }
 
-    private static Key generateKey(String encryptionKey) throws Exception {
-        byte[] keyBytes = encryptionKey.getBytes();
-        return new SecretKeySpec(keyBytes, AES_ALGORITHM);
+    // FIX: Use PBKDF2 for key derivation with salt
+    private static SecretKey generateKey(String encryptionKey, byte[] salt) throws Exception {
+        SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
+        KeySpec spec = new PBEKeySpec(encryptionKey.toCharArray(), salt, PBKDF2_ITERATIONS, KEY_SIZE);
+        SecretKey tmp = factory.generateSecret(spec);
+        return new SecretKeySpec(tmp.getEncoded(), "AES");
     }
 }
 
+// FIX EXPLANATION: This fix uses PBKDF2 with a random salt for key derivation, ensuring strong, unpredictable keys even from weak passwords. It uses AES in CBC mode with a random IV, which is prepended to the ciphertext for decryption. This prevents ECB mode weaknesses and ensures semantic security. The salt and IV are stored with the ciphertext, and all cryptographic parameters are securely generated. This approach follows industry best practices for file encryption.
+