org.bouncycastle.crypto.macs

Class ISO9797Alg3Mac

Implemented Interfaces:
Mac

public class ISO9797Alg3Mac
extends java.lang.Object
implements Mac

DES based CBC Block Cipher MAC according to ISO9797, algorithm 3 (ANSI X9.19 Retail MAC) This could as well be derived from CBCBlockCipherMac, but then the property mac in the base class must be changed to protected

Constructor Summary

ISO9797Alg3Mac(BlockCipher cipher)
create a Retail-MAC based on a CBC block cipher.
ISO9797Alg3Mac(BlockCipher cipher, int macSizeInBits)
create a Retail-MAC based on a block cipher with the size of the MAC been given in bits.
ISO9797Alg3Mac(BlockCipher cipher, int macSizeInBits, BlockCipherPadding padding)
create a standard MAC based on a block cipher with the size of the MAC been given in bits.
ISO9797Alg3Mac(BlockCipher cipher, BlockCipherPadding padding)
create a Retail-MAC based on a CBC block cipher.

Method Summary

int
doFinal(byte[] out, int outOff)
String
getAlgorithmName()
int
getMacSize()
void
init(CipherParameters params)
void
reset()
Reset the mac generator.
void
update(byte in)
void
update(byte[] in, int inOff, int len)

Constructor Details

ISO9797Alg3Mac

public ISO9797Alg3Mac(BlockCipher cipher)
create a Retail-MAC based on a CBC block cipher. This will produce an authentication code of the length of the block size of the cipher.
Parameters:
cipher - the cipher to be used as the basis of the MAC generation. This must be DESEngine.

ISO9797Alg3Mac

public ISO9797Alg3Mac(BlockCipher cipher,
                      int macSizeInBits)
create a Retail-MAC based on a block cipher with the size of the MAC been given in bits. This class uses single DES CBC mode as the basis for the MAC generation.

Note: the size of the MAC must be at least 24 bits (FIPS Publication 81), or 16 bits if being used as a data authenticator (FIPS Publication 113), and in general should be less than the size of the block cipher as it reduces the chance of an exhaustive attack (see Handbook of Applied Cryptography).

Parameters:
cipher - the cipher to be used as the basis of the MAC generation.
macSizeInBits - the size of the MAC in bits, must be a multiple of 8.

ISO9797Alg3Mac

public ISO9797Alg3Mac(BlockCipher cipher,
                      int macSizeInBits,
                      BlockCipherPadding padding)
create a standard MAC based on a block cipher with the size of the MAC been given in bits. This class uses single DES CBC mode as the basis for the MAC generation. The final block is decrypted and then encrypted using the middle and right part of the key.

Note: the size of the MAC must be at least 24 bits (FIPS Publication 81), or 16 bits if being used as a data authenticator (FIPS Publication 113), and in general should be less than the size of the block cipher as it reduces the chance of an exhaustive attack (see Handbook of Applied Cryptography).

Parameters:
cipher - the cipher to be used as the basis of the MAC generation.
macSizeInBits - the size of the MAC in bits, must be a multiple of 8.
padding - the padding to be used to complete the last block.

ISO9797Alg3Mac

public ISO9797Alg3Mac(BlockCipher cipher,
                      BlockCipherPadding padding)
create a Retail-MAC based on a CBC block cipher. This will produce an authentication code of the length of the block size of the cipher.
Parameters:
cipher - the cipher to be used as the basis of the MAC generation.
padding - the padding to be used to complete the last block.

Method Details

doFinal

public int doFinal(byte[] out,
                   int outOff)
Specified by:
doFinal in interface Mac

getAlgorithmName

public String getAlgorithmName()
Specified by:
getAlgorithmName in interface Mac

getMacSize

public int getMacSize()
Specified by:
getMacSize in interface Mac

init

public void init(CipherParameters params)
Specified by:
init in interface Mac

reset

public void reset()
Reset the mac generator.
Specified by:
reset in interface Mac

update

public void update(byte in)
Specified by:
update in interface Mac

update

public void update(byte[] in,
                   int inOff,
                   int len)
Specified by:
update in interface Mac