public class

ISO9797Alg3Mac

extends Object
implements Mac
java.lang.Object
   ↳ org.bouncycastle.crypto.macs.ISO9797Alg3Mac

Class Overview

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

Summary

Public Constructors
ISO9797Alg3Mac(BlockCipher cipher)
create a Retail-MAC based on a CBC block cipher.
ISO9797Alg3Mac(BlockCipher cipher, BlockCipherPadding padding)
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.
Public Methods
int doFinal(byte[] out, int outOff)
Compute the final stage of the MAC writing the output to the out parameter.
String getAlgorithmName()
Return the name of the algorithm the MAC implements.
int getMacSize()
Return the block size for this MAC (in bytes).
void init(CipherParameters params)
Initialise the MAC.
void reset()
Reset the mac generator.
void update(byte[] in, int inOff, int len)
void update(byte in)
add a single byte to the mac for processing.
[Expand]
Inherited Methods
From class java.lang.Object
From interface org.bouncycastle.crypto.Mac

Public Constructors

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.

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.

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.

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.

Public Methods

public int doFinal (byte[] out, int outOff)

Compute the final stage of the MAC writing the output to the out parameter.

doFinal leaves the MAC in the same state it was after the last init.

Parameters
out the array the MAC is to be output to.
outOff the offset into the out buffer the output is to start at.

public String getAlgorithmName ()

Return the name of the algorithm the MAC implements.

Returns
  • the name of the algorithm the MAC implements.

public int getMacSize ()

Return the block size for this MAC (in bytes).

Returns
  • the block size for this MAC in bytes.

public void init (CipherParameters params)

Initialise the MAC.

Parameters
params the key and other data required by the MAC.

public void reset ()

Reset the mac generator.

public void update (byte[] in, int inOff, int len)

public void update (byte in)

add a single byte to the mac for processing.

Parameters
in the byte to be processed.