gnu.javax.crypto.mac
Class HMac
- Cloneable, IMac
The implementation of the
HMAC (Keyed-Hash Message Authentication
Code).
HMAC can be used in combination with any iterated cryptographic hash
function.
HMAC also uses a
secret key for calculation and
verification of the message authentication values. The main goals behind this
construction are:
- To use, without modifications, available hash functions. In particular,
hash functions that perform well in software, and for which code is freely
and widely available.
- To preserve the original performance of the hash function without
incurring a significant degradation.
- To use and handle keys in a simple way.
- To have a well understood cryptographic analysis of the strength of the
authentication mechanism based on reasonable assumptions on the underlying
hash function.
- To allow for easy replaceability of the underlying hash function in case
that faster or more secure hash functions are found or required.
References:
- RFC 2104HMAC:
Keyed-Hashing for Message Authentication.
H. Krawczyk, M. Bellare, and R. Canetti.
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.
|
void | init(Map attributes) - Initialises the algorithm with designated attributes.
|
void | reset() - Resets the algorithm instance for re-initialisation and use with other
characteristics.
|
boolean | selfTest() - A basic test.
|
clone , equals , finalize , getClass , hashCode , notify , notifyAll , toString , wait , wait , wait |
ipad
protected byte[] ipad
HMac
protected HMac(IMessageDigest underlyingHash)
Trivial constructor for use by concrete subclasses.
underlyingHash
- the underlying hash algorithm instance.
digest
public byte[] digest()
Completes the MAC by performing final operations such as padding
and resetting the instance.
- digest in interface IMac
- digest in interface BaseMac
- the array of bytes representing the MAC value.
init
public void init(Map attributes)
throws InvalidKeyException,
IllegalStateException
Initialises the algorithm with designated attributes. Permissible names and
values are described in the class documentation above.
- init in interface IMac
- init in interface BaseMac
attributes
- a set of name-value pairs that describe the desired
future instance behaviour.
reset
public void reset()
Resets the algorithm instance for re-initialisation and use with other
characteristics. This method always succeeds.
- reset in interface IMac
- reset in interface BaseMac
selfTest
public boolean selfTest()
A basic test. Ensures that the MAC of a pre-determined message is equal to
a known pre-computed value.
- selfTest in interface IMac
- selfTest in interface BaseMac
true
if the implementation passes a basic self-test.
Returns false
otherwise.
HMac.java --
Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc.
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