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## Package gnu.crypto.mac

Provides a basic API for using Message Authentication Code (MAC) algorithms.

See:
Description

Interface Summary
IMac | The basic visible methods of any MAC (Message Authentication Code) algorithm.

Class Summary
BaseMac | A base abstract class to facilitate MAC (Message Authentication Code) implementations.
HMac | The implementation of the HMAC (Keyed-Hash Message Authentication Code).
HMacFactory | A Factory to instantiate Keyed-Hash Message Authentication Code (HMAC) algorithm instances.
MacFactory | A Factory that instantiates instances of every supported Message Authentication Code algorithms, including all HMAC algorithms.
MacInputStream | A filtering input stream that computes a MAC (message authentication code) over all data read from the stream.
MacOutputStream | A filtering output stream that computes a MAC (message authentication code) over all data written to the stream.
TMMH16 | TMMH is a universal hash function suitable for message authentication in the Wegman-Carter paradigm, as in the Stream Cipher Security Transform.
UHash32 | UHASH is a keyed hash function, which takes as input a string of arbitrary length, and produces as output a string of fixed length (such as 8 bytes).
UMac32 | The implementation of the UMAC (Universal Message Authentication Code).

## Package gnu.crypto.mac Description

Provides a basic API for using Message Authentication Code (MAC) algorithms.

## Package overview

A Message Authentication Code, or MAC, is akin to a keyed hash function, in that it produces a fixed-length identifier for variable-length data along with a key. The purpose of a MAC is to guarantee the integrity and authenticity of data, as it is computationally infeasible to fake a MAC without knowledge of the key.

The following diagram shows the important classes participating in this package:

Here is a simple example of how to use the HMAC algorithm, with a SHA-1 hash.

    IMac mac = MacFactory.getInstance("HMAC-SHA-160");

    HashMap attributes = new HashMap();
    attributes.put(IMac.MAC_KEY_MATERIAL, key_bytes);
    attributes.put(IMac.TRUNCATED_SIZE, new Integer(12));
    mac.init(attributes);

    mac.update(input, 0, input.length);

    byte[] result = mac.digest();

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