How to encrypt or decrypt with Rijndael and a block-size of 256 bits?

java encryption cryptography aes rijndael
Laures picture Laures · Nov 10, 2011 · Viewed 11.2k times · Source

For certain reasons I need to implement Rijndael de/compression with a blocksize of 256 bits instead of AES which uses a block size of 128 bits (reason: data is encrypted in PHP using Rijndael...).

How can I change the block-size for a cipher?

If i just get a cipher with "RIJNDAEL/CFB/PKCS5Padding" and try to initialize a IV with 256 bits I get an exception, because the block-size is only 128 bits.

Answer

President James K. Polk picture President James K. Polk · Nov 10, 2011

There is no support in any of the Sun JCE providers for anything other than Rijndael with the 128-bit blocksize: this is the AES algorithm. To get rijndael with the 256-bit blocksize you will have to go somewhere else. I suggest the Bouncycastle java library. The RijndaelEngine class has a constructor that accepts a block size in bits. Most people find the PaddedBufferedBlockCipher class to be more convenient when used with suitable padding, e.g.

PaddedBufferedBlockCipher c = new PaddedBufferedBlockCipher(new RijndaelEngine(256), new PKCS7Padding());

Related questions

Java 256-bit AES Password-Based Encryption

I need to implement 256 bit AES encryption, but all the examples I have found online use a "KeyGenerator" to generate a 256 bit key, but I would like to use my own passkey. How can I create my own key? I …

Read More
Java AES: No installed provider supports this key: javax.crypto.spec.SecretKeySpec

I'm trying to set up 128 bit AES encryption, and I'm getting an exception thrown on my Cipher.init: No installed provider supports this key: javax.crypto.spec.SecretKeySpec I'm generating the Key on the client side using the following code: …

Read More
Given final block not properly padded

I am trying to implement password based encryption algorithm, but I get this exception: javax.crypto.BadPaddingException: Given final block not properly padded What might be the problem? Here is my code: public class PasswordCrypter { private Key key; public PasswordCrypter(…

Read More