gnu.javax.crypto.mac
Class TMMH16
- Cloneable, IMac
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.
TMMH16()- Trivial 0-arguments constructor.
|
Object | clone()- This method may be called to create a new copy of the
Object.
|
byte[] | digest()
|
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(Map<K,V> attributes)
|
int | macSize()
|
void | reset()
|
boolean | selfTest()
|
void | update(byte b)
|
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.
|
void | update(byte[] b, int offset, int len)
|
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.
|
clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
KEYSTREAM
public static final String KEYSTREAM
- "gnu.crypto.mac.tmmh.keystream"
PREFIX
public static final String PREFIX
- "gnu.crypto.mac.tmmh.prefix"
TMMH16
public TMMH16()
Trivial 0-arguments constructor.
clone
public Object clone()
throws CloneNotSupportedException This method may be called to create a new copy of the
Object. The typical behavior is as follows:
o == o.clone() is falseo.getClass() == o.clone().getClass()
is trueo.equals(o) is true
However, these are not strict requirements, and may
be violated if necessary. Of the three requirements, the
last is the most commonly violated, particularly if the
subclass does not override
Object.equals(Object).
If the Object you call clone() on does not implement
Cloneable (which is a placeholder interface), then
a CloneNotSupportedException is thrown. Notice that
Object does not implement Cloneable; this method exists
as a convenience for subclasses that do.
Object's implementation of clone allocates space for the
new Object using the correct class, without calling any
constructors, and then fills in all of the new field values
with the old field values. Thus, it is a shallow copy.
However, subclasses are permitted to make a deep copy.
All array types implement Cloneable, and override
this method as follows (it should never fail):
public Object clone()
{
try
{
super.clone();
}
catch (CloneNotSupportedException e)
{
throw new InternalError(e.getMessage());
}
}
- clone in interface IMac
- clone in interface BaseMac
digest
public byte[] digest(IRandom prng)
Similar to the same method with no arguments, but uses the designated
random number generator to compute needed keying material.
prng - the source of randomness to use.
- the final result of the algorithm.
update
public 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.
b - the byte to process.prng - the source of randomness to use.
update
public 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.
b - the byte array to process.offset - the starting offset in b to start considering
the bytes to process.len - the number of bytes in b starting from
offset to process.prng - the source of randomness to use.
TMMH16.java --
Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc.
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