net.ninthtest.crypto.provider.helix

Class HelixMac

java.lang.Object

javax.crypto.MacSpi

net.ninthtest.crypto.provider.helix.HelixMac

public final class HelixMac
extends MacSpi

This class provides the MAC generation operation for the Helix stream cipher.

Version:

1.0

Author:

Matthew Zipay (mattz@ninthtest.net)

Constructor Summary

Constructors

Constructor and Description
HelixMac() Creates a new HelixMac and performs the provider self-integrity check.

Method Summary

Modifier and Type	Method and Description
protected byte[]	engineDoFinal() Completes the MAC computation and resets the MAC for further use, maintaining the secret key that the MAC was initialized with.
protected int	engineGetMacLength() Returns the length of the MAC in bytes.
protected void	engineInit(Key key, AlgorithmParameterSpec params) Initializes the MAC with the given (secret) key and algorithm parameters.
protected void	engineReset() Resets the MAC for further use, maintaining the secret key that the MAC was initialized with.
protected void	engineUpdate(byte input) Processes the given byte.
protected void	engineUpdate(byte[] input, int offset, int len) Processes the first len bytes in input, starting at offset inclusive.

Methods inherited from class javax.crypto.MacSpi

clone, engineUpdate

Methods inherited from class java.lang.Object

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

Constructor Detail

HelixMac

public HelixMac()

Creates a new HelixMac and performs the provider self-integrity check.

Method Detail

engineGetMacLength

protected int engineGetMacLength()

Returns the length of the MAC in bytes.

Specified by:

engineGetMacLength in class MacSpi

Returns:

the length of a Helix MAC expressed in bytes (always 16 )

See Also:

MacSpi.engineGetMacLength()

engineInit

protected void engineInit(Key key,
                          AlgorithmParameterSpec params)
                   throws InvalidKeyException,
                          InvalidAlgorithmParameterException

Initializes the MAC with the given (secret) key and algorithm parameters.

If a MAC is non-null in params, it is ignored.

Specified by:

engineInit in class MacSpi

Parameters:

key - the secret key for an MAC generation (encryption) operation (must be a Helix SecretKey)

params - the algorithm parameters (must be a HelixParameterSpec )

Throws:

InvalidKeyException - if key is null or not a Helix SecretKey

InvalidAlgorithmParameterException - if params is null or not a HelixParameterSpec

See Also:

MacSpi.engineInit(java.security.Key, java.security.spec.AlgorithmParameterSpec)

engineUpdate

protected void engineUpdate(byte input)

Processes the given byte.

Specified by:

engineUpdate in class MacSpi

Parameters:

input - the input byte to be processed

See Also:

MacSpi.engineUpdate(byte)

engineUpdate

protected void engineUpdate(byte[] input,
                            int offset,
                            int len)

Processes the first len bytes in input, starting at offset inclusive.

Specified by:

engineUpdate in class MacSpi

Parameters:

input - the input buffer

offset - the index into input where the input bytes begin

len - the number of bytes to be used from input (beginning at offset)

See Also:

MacSpi.engineUpdate(byte[], int, int)

engineDoFinal

protected byte[] engineDoFinal()

Completes the MAC computation and resets the MAC for further use, maintaining the secret key that the MAC was initialized with.

Specified by:

engineDoFinal in class MacSpi

Returns:

the generated 16-byte MAC

See Also:

MacSpi.engineDoFinal()

engineReset

protected void engineReset()

Resets the MAC for further use, maintaining the secret key that the MAC was initialized with.

The Helix nonce is also maintained. Re-using a HelixMac in this manner is not recommended; instead, re-initialize the Mac instance with a new nonce.

Specified by:

engineReset in class MacSpi

See Also:

MacSpi.engineReset()