org.clazzes.optional.sec
Class AESCipher

java.lang.Object
  extended by org.clazzes.optional.sec.AESCipher
All Implemented Interfaces:
BlockCipher

public class AESCipher
extends java.lang.Object
implements BlockCipher

Implementation of AES base copied from bouncycastle's AESFastEngine. an implementation of the AES (Rijndael), from FIPS-197.

For further details see: http://csrc.nist.gov/encryption/aes/. This implementation is based on optimizations from Dr. Brian Gladman's paper and C code at http://fp.gladman.plus.com/cryptography_technology/rijndael/ There are three levels of tradeoff of speed vs memory Because java has no preprocessor, they are written as three separate classes from which to choose The fastest uses 8Kbytes of static tables to precompute round calculations, 4 256 word tables for encryption and 4 for decryption. The middle performance version uses only one 256 word table for each, for a total of 2Kbytes, adding 12 rotate operations per round to compute the values contained in the other tables from the contents of the first The slowest version uses no static tables at all and computes the values in each round

This file contains the fast version with 8Kbytes of static tables for round precomputation


Constructor Summary
AESCipher()
          default constructor - 128 bit block size.
 
Method Summary
 java.lang.String getAlgorithmName()
          Return the name of the algorithm the cipher implements.
 int getBlockSize()
           
 BlockCipher getUnderlyingCipher()
          return the underlying block cipher that we are wrapping or null, if we do wrap another cipher.
 void init(byte[] key, boolean useForEncryption)
          initialise an AES cipher.
 int processBlock(byte[] in, int inOff, byte[] out, int outOff)
          Proceed the next block of BlockCipher.getBlockSize() bytes from the input.
 void reset()
          Reset this cipher to state of the last call to #init(byte[], byte[], boolean).
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

AESCipher

public AESCipher()
default constructor - 128 bit block size.

Method Detail

init

public void init(byte[] key,
                 boolean useForEncryption)
initialise an AES cipher.

Specified by:
init in interface BlockCipher
Parameters:
useForEncryption - whether or not we are for encryption.
params - the parameters required to set up the cipher.

getAlgorithmName

public java.lang.String getAlgorithmName()
Description copied from interface: BlockCipher
Return the name of the algorithm the cipher implements.

Specified by:
getAlgorithmName in interface BlockCipher
Returns:
the name of the algorithm the cipher implements.

getBlockSize

public int getBlockSize()
Specified by:
getBlockSize in interface BlockCipher
Returns:
The block size used for the BlockCipher.processBlock(byte[], int, byte[], int) operation.

processBlock

public int processBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)
Description copied from interface: BlockCipher
Proceed the next block of BlockCipher.getBlockSize() bytes from the input.

Specified by:
processBlock in interface BlockCipher
Parameters:
in - The buffer where the input is stored. BlockCipher.getBlockSize() bytes starting with in_off will be consumed.
inOff - The offset at which the input data starts.
out - The buffer where the output is stored. BlockCipher.getBlockSize() bytes starting with out_off will be written.
outOff - The offset at which the output will be stored.
Returns:
The block size aka the number of bytes written.

reset

public void reset()
Description copied from interface: BlockCipher
Reset this cipher to state of the last call to #init(byte[], byte[], boolean).

Specified by:
reset in interface BlockCipher

getUnderlyingCipher

public BlockCipher getUnderlyingCipher()
Description copied from interface: BlockCipher
return the underlying block cipher that we are wrapping or null, if we do wrap another cipher.

Specified by:
getUnderlyingCipher in interface BlockCipher
Returns:
the underlying block cipher that we are wrapping.


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