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BadPaddingException when decrypting encrypted stream

开发者 https://www.devze.com 2023-04-12 14:10 出处:网络
I\'m using javax.crypto.Cipher to encrypt a file and then decrypt it but I\'m still getting the BadPaddingException. The following class receives inputStream from the input file and outputStream for t

I'm using javax.crypto.Cipher to encrypt a file and then decrypt it but I'm still getting the BadPaddingException. The following class receives inputStream from the input file and outputStream for the output file.

Error

13:22:15,049 ERROR [STDERR] javax.crypto.BadPaddingException: Given final block not properly padded
13:22:15,081 ERROR [STDERR]     at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
13:22:15,096 ERROR [STDERR]     at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
13:22:15,128 ERROR [STDERR]     at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)
13:22:15,143 ERROR [STDERR]     at javax.crypto.Cipher.doFinal(DashoA13*..)

Code

public class CipherAES implements Cipher {

    private static final Logger logger = Logger.getLogger(CipherAES.class);

    private Key key;

    public CipherAES() {
        this.key = generateKey();
    }

    private Key generateKey() {
        try {
            KeyGenerator generator;
            generator = KeyGenerator.getInstance("AES");
            generator.init(new SecureRandom());
            return generator.generateKey();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    public void decrypt(InputStream inputStream, OutputStream outputStream) throws IOException {
        try {
            javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("AES");
            cipher.init(javax.crypto.Cipher.DECRYPT_MODE, key);
            byte[] raw = IOUtil.toByteArray(inputStream);
            byte[] base64Decoded = Base64.decodeBase64(raw);
            byte[] decryptedData = cipher.doFinal(base64Decoded);
            outputStream.write(decryptedData);
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } finally {
            inputStream.close();
            outputStream.close();
        }
    }

    @Override
    public void encrypt(InputStream inputStream, OutputStream outputStream) throws IOException {
        try {
            javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("AES");
            cipher.init(javax.crypto.Cipher.ENCRYPT_MODE, key);
            byte[] raw = IOUtil.toByteArray(inputStream);
            byte[] encryptedData = cipher.doFinal(raw);
            byte[] base64Encoded = Base64.encodeBase64(encryptedData);
            outputStream.write(base64Encoded);
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } finally {
            inputStream.close();
            outputStream.close();
        }
    }

}

LOG

# this is log from encryption
raw: 
    [97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122]
encrypted: 
    [92, -104, -48, -10, 95, -3, -21, 46, 27, -60, -115, 85, 114, -95, -126, 108, 88, -105, 94, -84, 86, 86, -75, -83, -73, 24, -109, 86, -34, 83, -35, 106]
base64Encoded: 
    [88, 74, 106, 81, 57, 108, 47, 57, 54, 121, 52, 98, 120, 73, 49, 86, 99, 113, 71, 67, 98, 70, 105, 88, 88, 113, 120, 87, 86, 114, 87, 116, 116, 120, 105, 84, 86, 116, 53, 84, 51, 87, 111, 61]

# this is from decryption
raw (this is the base64Encoded): 
    [88, 74,开发者_运维技巧 106, 81, 57, 108, 47, 57, 54, 121, 52, 98, 120, 73, 49, 86, 99, 113, 71, 67, 98, 70, 105, 88, 88, 113, 120, 87, 86, 114, 87, 116, 116, 120, 105, 84, 86, 116, 53, 84, 51, 87, 111, 61]
base64Decoded (this is the encrypted): 
    [92, -104, -48, -10, 95, -3, -21, 46, 27, -60, -115, 85, 114, -95, -126, 108, 88, -105, 94, -84, 86, 86, -75, -83, -73, 24, -109, 86, -34, 83, -35, 106]
decrypted (this should be the raw from the encryption): 
    I don't know - the exception is thrown 


Well your encryption code seems somewhat flaky to start with:

byte[] raw = IOUtil.toByteArray(inputStream);
byte[] encryptedData = cipher.doFinal();

How about giving the cipher the data it's meant to encrypt? I suspect you meant to pass in raw to the doFinal call.

I doubt that that's the complete problem, but it's at least a starting point.

EDIT for posterity: Judging by the comments, the problem was that different instances were being used for encryption and decryption, hence different keys.


BadPaddingException when decrypting encrypted stream is primarily due to saving encrypted data in wrong format

For details check out

http://themasterofmagik.wordpress.com/2014/03/19/simple-aes-encryption-and-decryption-in-java-part1/

It mentions which code was giving error and how it was resolved.

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