de.flexiprovider.core.mac
Class CMac

java.lang.Object
  |
  +--javax.crypto.MacSpi
        |
        +--de.flexiprovider.api.Mac
              |
              +--de.flexiprovider.core.mac.CMac

Direct Known Subclasses:

CMac.AES128, CMac.AES192, CMac.AES256, CMac.DESede

public class CMac

extends Mac

This is an implementaion of the CMAC ( NIST Special Publication 800-38B).

Author:

Paul Nguentcheu

Inner Class Summary

static class	CMac.AES128 CMAC with AES128 algorithm
static class	CMac.AES192 CMAC with AES192 algorithm
static class	CMac.AES256 CMAC with AES256 algorithm
static class	CMac.DESede CMAC with DESede algorithm

Constructor Summary

protected

CMac(BlockCipher blockCipher) This constructor is called by every subclass for specifying the particular algorithm to be used for CMAC computation.

Method Summary

byte[]	doFinal() Returns the calculated MAC value.
int	getMacLength() Returns the length of the calculated MAC value in bytes.
void	init(SecretKey key, AlgorithmParameterSpec params) Initializes this Mac Object with the given secret key and algorithm parameterSpec specification.
void	keySchedule(byte[] key) This method implements the CMac Key expansion.
void	reset() Reset this MAC object so that it may be used for further MAC computations.
void	update(byte b) Processes the given byte
void	update(byte[] bytes, int offset, int len) Processes the given number of bytes, supplied in a byte array starting at the given position.

Methods inherited from class de.flexiprovider.api.Mac

doFinal, doFinal, engineDoFinal, engineGetMacLength, engineInit, engineReset, engineUpdate, engineUpdate, init, update

Methods inherited from class javax.crypto.MacSpi

clone

Methods inherited from class java.lang.Object

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

Constructor Detail

CMac

protected CMac(BlockCipher blockCipher)

This constructor is called by every subclass for specifying the particular algorithm to be used for CMAC computation.

Parameters:

blockCipher - the cipher algorithm to use

Method Detail

doFinal

public byte[] doFinal()

Returns the calculated MAC value. After the MAC finally has been calculated, the MAC object is reset for further MAC computations.

Overrides:

doFinal in class Mac

Returns:

the calculated MAC value.

getMacLength

public int getMacLength()

Returns the length of the calculated MAC value in bytes.

Overrides:

getMacLength in class Mac

Returns:

the length of the MAC value

init

public void init(SecretKey key,
                 AlgorithmParameterSpec params)
          throws InvalidKeyException,
                 InvalidAlgorithmParameterException

Initializes this Mac Object with the given secret key and algorithm parameterSpec specification. The parameters are ignored.

Overrides:

init in class Mac

Parameters:

key - the secret key with which this MAC object is initialized.

params - the parameters

Throws:

InvalidKeyException - if the key is invalid.

InvalidAlgorithmParameterException - if the parameters are inappropriate for initializing the underlying block cipher.

keySchedule

public void keySchedule(byte[] key)

This method implements the CMac Key expansion. The subkeys K1 and K2 are stored in the variables K1, K2.

Parameters:

key - - the byte array containing the key.

reset

public void reset()

Reset this MAC object so that it may be used for further MAC computations.

Overrides:

reset in class Mac

update

public void update(byte b)

Processes the given byte

Overrides:

update in class Mac

Parameters:

b - the byte to be processed.

update

public void update(byte[] bytes,
                   int offset,
                   int len)

Processes the given number of bytes, supplied in a byte array starting at the given position.

Overrides:

update in class Mac

Parameters:

bytes - byte array containing the message to be processed

offset - offset into the array to start from

len - number of bytes to be processed.