TMMH16 (GNU cryptographic primitives and tools, version 2.0.0)

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gnu.crypto.mac
Class TMMH16

java.lang.Object
  gnu.crypto.mac.BaseMac
      gnu.crypto.mac.TMMH16

All Implemented Interfaces:: java.lang.Cloneable, IMac

public class TMMH16
extends BaseMac

TMMH is a universal hash function suitable for message authentication in the Wegman-Carter paradigm, as in the Stream Cipher Security Transform. It is simple, quick, and especially appropriate for Digital Signal Processors and other processors with a fast multiply operation, though a straightforward implementation requires storage equal in length to the largest message to be hashed.

TMMH is a simple hash function which maps a key and a message to a hash value. There are two versions of TMMH: TMMH/16 and TMMH/32. TMMH can be used as a message authentication code, as described in Section 5 (see References).

The key, message, and hash value are all octet strings, and the lengths of these quantities are denoted as KEY_LENGTH, MESSAGE_LENGTH, and TAG_LENGTH, respectively. The values of KEY_LENGTH and TAG_LENGTH MUST be fixed for any particular fixed value of the key, and must obey the alignment restrictions described below.

The parameter MAX_HASH_LENGTH, which denotes the maximum value which MESSAGE_LENGTH may take, is equal to KEY_LENGTH - TAG_LENGTH.

References:

The Truncated Multi-Modular Hash Function (TMMH), David A. McGrew.

Version:: $Revision: 1.2 $

Field Summary
`static java.lang.String`	`KEYSTREAM`
`static java.lang.String`	`PREFIX`
`static java.lang.String`	`TAG_LENGTH`

Fields inherited from class gnu.crypto.mac.BaseMac

name, truncatedSize, underlyingHash

Fields inherited from interface gnu.crypto.mac.IMac

MAC_KEY_MATERIAL, TRUNCATED_SIZE

Constructor Summary
`TMMH16()` Trivial 0-arguments constructor.

Method Summary
`java.lang.Object`	`clone()` Returns a clone copy of this instance.
`byte[]`	`digest()` Completes the MAC by performing final operations such as padding and resetting the instance.
`byte[]`	`digest(IRandom prng)` Similar to the same method with no arguments, but uses the designated random number generator to compute needed keying material.
`void`	`init(java.util.Map attributes)` Initialises the algorithm with designated attributes.
`int`	`macSize()` Returns the output length in bytes of this MAC algorithm.
`void`	`reset()` Resets the algorithm instance for re-initialisation and use with other characteristics.
`boolean`	`selfTest()` A basic test.
`void`	`update(byte b)` Continues a MAC operation using the input byte.
`void`	`update(byte[] b, int offset, int len)` Continues a MAC operation, by filling the buffer, processing data in the algorithm's MAC_SIZE-bit block(s), updating the context and count, and buffering the remaining bytes in buffer for the next operation.
`void`	`update(byte[] b, int offset, int len, IRandom prng)` Similar to the same method with three arguments, but uses the designated random number generator to compute needed keying material.
`void`	`update(byte b, IRandom prng)` Similar to the same method with one argument, but uses the designated random number generator to compute needed keying material.

Methods inherited from class gnu.crypto.mac.BaseMac

name

Methods inherited from class java.lang.Object

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

Field Detail

TAG_LENGTH

public static final java.lang.String TAG_LENGTH

See Also:: Constant Field Values

KEYSTREAM

public static final java.lang.String KEYSTREAM

See Also:: Constant Field Values

PREFIX

public static final java.lang.String PREFIX

See Also:: Constant Field Values

Constructor Detail

TMMH16

public TMMH16()

Trivial 0-arguments constructor.

Method Detail