HMac (GNU cryptographic primitives and tools, version 2.0.0)

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gnu.crypto.mac
Class HMac

java.lang.Object
 extended bygnu.crypto.mac.BaseMac
 extended bygnu.crypto.mac.HMac

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

public class HMac
extends BaseMac

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.

Version:: $Revision: 1.2 $

Field Summary
`protected int`	`blockSize`
`protected byte[]`	`ipad`
`protected IMessageDigest`	`ipadHash`
`protected int`	`macSize`
`protected IMessageDigest`	`opadHash`
`static java.lang.String`	`USE_WITH_PKCS5_V2`

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
`protected`	`HMac(IMessageDigest underlyingHash)` Trivial constructor for use by concrete subclasses.

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.
`void`	`init(java.util.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.

Methods inherited from class gnu.crypto.mac.BaseMac

macSize, name, update, update

Methods inherited from class java.lang.Object

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

Field Detail

USE_WITH_PKCS5_V2

public static final java.lang.String USE_WITH_PKCS5_V2

See Also:: Constant Field Values

macSize

protected int macSize

blockSize

protected int blockSize

ipadHash

protected IMessageDigest ipadHash

opadHash

protected IMessageDigest opadHash

ipad

protected byte[] ipad

Constructor Detail

HMac

protected HMac(IMessageDigest underlyingHash)

Trivial constructor for use by concrete subclasses.

Parameters:

underlyingHash - the underlying hash algorithm instance.

Method Detail