Mac.java

/*-
 * Copyright (c) 2000 - 2009 The Legion Of The Bouncy Castle (http://www.bouncycastle.org)
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
 * to whom the Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package org.bouncycastle.crypto;


/**
 * The base interface for implementations of message authentication codes (MACs).
 */
public interface Mac
{
    /**
     * Initialise the MAC.
     *
     * @param params the key and other data required by the MAC.
     * @exception IllegalArgumentException if the params argument is
     * inappropriate.
     */
    public void init(CipherParameters params)
        throws IllegalArgumentException;

    /**
     * Return the name of the algorithm the MAC implements.
     *
     * @return the name of the algorithm the MAC implements.
     */
    public String getAlgorithmName();

    /**
     * Return the block size for this MAC (in bytes).
     *
     * @return the block size for this MAC in bytes.
     */
    public int getMacSize();

    /**
     * add a single byte to the mac for processing.
     *
     * @param in the byte to be processed.
     * @exception IllegalStateException if the MAC is not initialised.
     */
    public void update(byte in)
        throws IllegalStateException;

    /**
     * @param in the array containing the input.
     * @param inOff the index in the array the data begins at.
     * @param len the length of the input starting at inOff.
     * @exception IllegalStateException if the MAC is not initialised.
     * @exception DataLengthException if there isn't enough data in in.
     */
    public void update(byte[] in, int inOff, int len)
        throws DataLengthException, IllegalStateException;

    /**
     * Compute the final stage of the MAC writing the output to the out
     * parameter.
     * <p>
     * doFinal leaves the MAC in the same state it was after the last init.
     *
     * @param out the array the MAC is to be output to.
     * @param outOff the offset into the out buffer the output is to start at.
     * @exception DataLengthException if there isn't enough space in out.
     * @exception IllegalStateException if the MAC is not initialised.
     */
    public int doFinal(byte[] out, int outOff)
        throws DataLengthException, IllegalStateException;

    /**
     * Reset the MAC. At the end of resetting the MAC should be in the
     * in the same state it was after the last init (if there was one).
     */
    public void reset();
}