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 cipher (in bytes).     *     * @return the block size for this cipher 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 statge 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();}