CODEWITHSUNDEEP
javaencryptionjava-meaes
Muto
Muto

Reputation: 61

BadPaddingExeception whilst decrypting AES256

Currently having issues with the decryption of an AES hash.

When i encrypt using AES256 i get the following result (After base64 encoding)

07sKQfb9dN86XAMxFmVKHQAAAAAAAAAAAAAAAAAAAAA=

I believe my issue is with the AAAAAAAA etc. for some reason I think anyway the padding isn't being removed during decryption.

My code

public String encrypt(String key, String initVector, String value) throws Exception {
        IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"), 0, initVector.getBytes().length);
        SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), 0, key.getBytes().length, "AES");

        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);

        byte[] encrypted = new byte[32];

        cipher.doFinal(value.getBytes(), 0, value.getBytes().length, encrypted, 0);

        System.out.println("Base64: " + Base64.encode(encrypted));
        System.out.println("Hex: " + bytesToHex(encrypted));

        return Base64.encode(encrypted);
}

public String decrypt(String key, String initVector, String encrypted) {
    try {
        IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"), 0, initVector.getBytes().length);
        SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), 0, key.getBytes().length, "AES");

        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);

        byte[] decrypted = new byte[64];
        cipher.doFinal(Base64.decode(encrypted), 0, Base64.decode(encrypted).length, decrypted, 0);

        return new String(decrypted);
    } catch (Exception ex) {
        ex.printStackTrace();
    }

    return null;
}

What i am expecting when i encode base64 07sKQfb9dN86XAMxFmVKHQ=

String i am encrypting: Test Secret key: password12345678password12345678

Upvotes: 0

Views: 50

Answers (1)

gusto2
gusto2

Reputation: 12075

    byte[] decrypted = new byte[64];

you created a 64 byte array but the decrypted value may be shorter (Java doesn't use zero string terminator unlike C does). So you should not make assumption over the parameter length

try using 

encrypted = cipher.doFinal(value.getBytes());

and 

decrypted = cipher.doFinal(Base64.decode(encrypted));

Upvotes: 0

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