Java tutorial
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(); }