Example

The following example encrypts and decrypts a byte array with the AES in CFB mode. See the next chapter on padding for instances where the input is not a multiple of the cipher or mode's block size.

 IMode mode = ModeFactory.getInstance("CFB", "AES", 16);
 Map attributes = new HashMap();
 
 // These attributes are defined in gnu.crypto.cipher.IBlockCipher.
 attributes.put(IMode.KEY_MATERIAL, key_bytes);
 attributes.put(IMode.CIPHER_BLOCK_SIZE, new Integer(16));
 
 // These attributes are defined in IMode.
 attributes.put(IMode.STATE, new Integer(IMode.ENCRYPTION));
 attributes.put(IMode.IV, iv_bytes);
 mode.init(attributes);
 int bs = mode.currentBlockSize();
 
 for (int i = 0; i + bs < pt.length; i += bs)
 {
 mode.update(pt, i, ct, i);
 }
 
 mode.reset();
 attributes.put(IMode.STATE, new Integer(IMode.DECRYPTION);
 mode.init(attributes);
 
 for (int i = 0; i + bs < ct.length; i += bs)
 {
 mode.update(ct, i, cpt, i);
 }