org.clazzes.optional.sec
Class CBCCipher

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

public class CBCCipher
extends java.lang.Object
implements BlockCipher

CBC cipher mode for symmetric ciphers. copied from bouncycastle.


Constructor Summary
CBCCipher(BlockCipher cipher)
          Basic constructor.
 
Method Summary
 java.lang.String getAlgorithmName()
          return the algorithm name and mode.
 int getBlockSize()
          return the block size of the underlying cipher.
 BlockCipher getUnderlyingCipher()
          return the underlying block cipher that we are wrapping.
 void init(byte[] iv, boolean forEncryption)
          Initialize the cipher and, possibly, the initialization vector (IV).
 int processBlock(byte[] in, int inOff, byte[] out, int outOff)
          Process one block of input from the array in and write it to the out array.
 void reset()
          reset the chaining vector back to the IV and reset the underlying cipher.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

CBCCipher

public CBCCipher(BlockCipher cipher)
Basic constructor.

Parameters:
cipher - the block cipher to be used as the basis of chaining, which should have been initialized..
Method Detail

getUnderlyingCipher

public BlockCipher getUnderlyingCipher()
return the underlying block cipher that we are wrapping.

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

init

public void init(byte[] iv,
                 boolean forEncryption)
Initialize the cipher and, possibly, the initialization vector (IV). If an IV isn't passed as part of the parameter, the IV will be all zeros.

Specified by:
init in interface BlockCipher
Parameters:
iv - The key for basic ciphers or initialization vector for cipher modes or null, if no key or initialization vector is needed.
forEncryption - Whether we want to encrypt. false means to set up this cipher for decryption.

getAlgorithmName

public java.lang.String getAlgorithmName()
return the algorithm name and mode.

Specified by:
getAlgorithmName in interface BlockCipher
Returns:
the name of the underlying algorithm followed by "/CBC".

getBlockSize

public int getBlockSize()
return the block size of the underlying cipher.

Specified by:
getBlockSize in interface BlockCipher
Returns:
the block size of the underlying cipher.

processBlock

public int processBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)
Process one block of input from the array in and write it to the out array.

Specified by:
processBlock in interface BlockCipher
Parameters:
in - the array containing the input data.
inOff - offset into the in array the data starts at.
out - the array the output data will be copied into.
outOff - the offset into the out array the output will start at.
Returns:
the number of bytes processed and produced.
Throws:
DataLengthException - if there isn't enough data in in, or space in out.
java.lang.IllegalStateException - if the cipher isn't initialised.

reset

public void reset()
reset the chaining vector back to the IV and reset the underlying cipher.

Specified by:
reset in interface BlockCipher


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