FileDocCategorySizeDatePackage
SICBlockCipher.javaAPI DocAzureus 3.0.3.42501Tue Jun 08 05:12:58 BST 2004org.bouncycastle.crypto.modes

SICBlockCipher

public class SICBlockCipher extends Object implements org.bouncycastle.crypto.BlockCipher
Implements the Segmented Integer Counter (SIC) mode on top of a simple block cipher. This mode is also known as CTR mode.

Fields Summary
private org.bouncycastle.crypto.BlockCipher
cipher
private int
blockSize
private byte[]
IV
private byte[]
counter
private byte[]
counterOut
private boolean
encrypting
Constructors Summary
public SICBlockCipher(org.bouncycastle.crypto.BlockCipher c)
Basic constructor.

param
c the block cipher to be used.



               
     
    this.cipher = c;
    this.blockSize = cipher.getBlockSize();
    this.IV = new byte[blockSize];
    this.counter = new byte[blockSize];
    this.counterOut = new byte[blockSize];
Methods Summary
public java.lang.StringgetAlgorithmName()

    return cipher.getAlgorithmName() + "/SIC";
public intgetBlockSize()

    return cipher.getBlockSize();
public org.bouncycastle.crypto.BlockCiphergetUnderlyingCipher()
return the underlying block cipher that we are wrapping.

return
the underlying block cipher that we are wrapping.

    return cipher;
public voidinit(boolean forEncryption, org.bouncycastle.crypto.CipherParameters params)

    this.encrypting = forEncryption;

    if (params instanceof ParametersWithIV) {
      ParametersWithIV ivParam = (ParametersWithIV)params;
      byte[]           iv      = ivParam.getIV();
      System.arraycopy(iv, 0, IV, 0, IV.length);

      reset();
      cipher.init(true, ivParam.getParameters());
    }
public intprocessBlock(byte[] in, int inOff, byte[] out, int outOff)

    cipher.processBlock(counter, 0, counterOut, 0);

    //
    // XOR the counterOut with the plaintext producing the cipher text
    //
    for (int i = 0; i < counterOut.length; i++) {
      out[outOff + i] = (byte)(counterOut[i] ^ in[inOff + i]);
    }

	int	carry = 1;
	
	for (int i = counter.length - 1; i >= 0; i--)
	{
		int	x = (counter[i] & 0xff) + carry;
		
		if (x > 0xff)
		{
			carry = 1;
		}
		else
		{
			carry = 0;
		}
		
		counter[i] = (byte)x;
	}

    return counter.length;
public voidreset()

    System.arraycopy(IV, 0, counter, 0, counter.length);
    cipher.reset();