freenet.crypt

Class CTRBlockCipher

java.lang.Object

freenet.crypt.CTRBlockCipher

public class CTRBlockCipher
extends java.lang.Object

Implements the Segmented Integer Counter (SIC) mode on top of a simple block cipher. This mode is also known as CTR mode.

Constructor Summary

Constructors

Constructor and Description
CTRBlockCipher(BlockCipher c) Basic constructor.

Method Summary

Modifier and Type	Method and Description
int	getBlockSize()
BlockCipher	getUnderlyingCipher() return the underlying block cipher that we are wrapping.
void	init(byte[] iv)
void	init(byte[] iv, int offset, int length) Initialize the cipher with an IV.
byte	processByte(byte in)
void	processBytes(byte[] input, int offsetIn, int length, byte[] output, int offsetOut) Encrypt some data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CTRBlockCipher

public CTRBlockCipher(BlockCipher c)

Basic constructor.

Parameters:

c - the block cipher to be used.

Method Detail

getUnderlyingCipher

public BlockCipher getUnderlyingCipher()

return the underlying block cipher that we are wrapping.

Returns:

the underlying block cipher that we are wrapping.

init

public void init(byte[] iv,
                 int offset,
                 int length)
          throws java.lang.IllegalArgumentException

Initialize the cipher with an IV. Must only be called once for any given IV!

Parameters:

iv - The initialization vector. This is the initial value of the plaintext counter. The plaintext is XORed with a sequence of bytes consisting of the encryption of successive values of the counter.

Throws:

java.lang.IllegalArgumentException - If the IV length is wrong.

init

public void init(byte[] iv)
          throws java.lang.IllegalArgumentException

Throws:

java.lang.IllegalArgumentException

getBlockSize

public int getBlockSize()

processByte

public byte processByte(byte in)

processBytes

public void processBytes(byte[] input,
                         int offsetIn,
                         int length,
                         byte[] output,
                         int offsetOut)

Encrypt some data.

Parameters:

input - The input data array.

offsetIn - The offset within the input data array to the first byte.

length - The number of bytes to encrypt.

output - The output data array.

offsetOut - The offset within the output data array to the first byte.