/*      
 * Copyright (c) 1995, 1996, 1997 Systemics Ltd
 * on behalf of the Cryptix Development Team.  All rights reserved.
 */
 
package cryptix.security;

import java.io.OutputStream;

/**
 * This class is an output stream that hashes the data sent to it using
 * the message digest that it has been constructed with.
 *
 * <P>
 * <b>References</b>
 *
 * <P>
 * <b>Copyright</b> &#169 1995, 1996, 1997
 * <a href="http://www.systemics.com/">Systemics Ltd</a>
 * on behalf of the
 * <a href="http://www.systemics.com/docs/cryptix/">
 * Cryptix Development Team</a>.
 * All rights reserved.
 *
 * <P>
 * @author Systemics Ltd
 * @see MessageDigest
 * @see SHAOutputStream
 * @see MD5OutputStream
 */
public class MessageDigestOutputStream extends OutputStream
{
        private byte tmp_byte_buf[] = new byte[1]; // temporary buffer for the write( int ) function.
        private MessageDigest md;
        
        /**
         * @param md0 the message digestor that is uses to hash the data.
         */
        public MessageDigestOutputStream( MessageDigest md0 )
        {
                md = md0;
        }

        /**
         * Writes a byte to the message digestor.
         * @param b     the byte
         */
        public final synchronized void
        write( int b )
        {
                tmp_byte_buf[0] = (byte)b;
                md.add( tmp_byte_buf );
        }

        /**
         * Writes an array of bytes to the message digestor
         * @param b     the data to be added to the hash
         */
        public final void
        write( byte b[] )
        {
                md.add( b );
        }

        /**
         * Writes a sub array of bytes to the message digestor. 
         * @param b     the data to be added to the hash
         * @param off   the start offset in the data
         * @param len   the number of bytes that are written
         */
        public final void
        write(byte b[], int off, int len)
        {
                md.add( b, off, len );
        }
        
        
        //
        // what about toByteArray and toMessageHash functions
        // like ByteArrayOutputStream ???
        /**
         * Completes the digest and resets.
         * @return      the final digest (as a byte array) of the data added
         */
        public final byte[]
        digest()
        {
                return md.digest();
        }

        /**
         * Completes the digest and resets.
         * @return      the final digest (as a Hash object) of the data added
         */
        public final MessageHash
        digestAsHash()
        {
                return md.digestAsHash();
        }
}