md512bitblock.java

一个非常好的ssh客户端实现

/******************************************************************************
 *
 * Copyright (c) 1999-2003 AppGate Network Security AB. All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code as
 * defined in and that are subject to the MindTerm Public Source License,
 * Version 2.0, (the 'License'). You may not use this file except in compliance
 * with the License.
 * 
 * You should have received a copy of the MindTerm Public Source License
 * along with this software; see the file LICENSE.  If not, write to
 * AppGate Network Security AB, Otterhallegatan 2, SE-41118 Goteborg, SWEDEN
 *
 *****************************************************************************/

package com.mindbright.security.digest;

import com.mindbright.jca.security.MessageDigest;
import com.mindbright.jca.security.DigestException;

public abstract class MD512BitBlock extends MessageDigest implements Cloneable {
    protected long   count;
    protected int    rest;
    protected byte[] buffer;
    protected int    digestLength;

    protected final static byte md4_padding[] = {
        (byte) 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
    };

    protected final static int rotateLeft(int x, int n) {
	return (x << n) | (x >>> (32 - n));
    }

    protected MD512BitBlock(String algorithm, int digestLength) {
	super(algorithm);
	buffer = new byte[64];
	count  = 0;
	rest   = 0;
	this.digestLength = digestLength;
    }

    public final Object clone() {
	MD512BitBlock c = cloneInternal();
	System.arraycopy(c.buffer, 0, buffer, 0, this.rest);
	c.count = this.count;
	c.rest  = this.rest;
	return c;
    }

    protected final void engineUpdate(byte input) {
	engineUpdate(new byte[] { input }, 0, 1);
    }

    protected final void engineUpdate(byte[] data, int offset, int length) {
        int left = 64 - rest;

        count += length;

	if(rest > 0 && length >= left) {
	    System.arraycopy(data, offset, buffer, rest, left);
	    transform(buffer, 0);
	    offset += left;
	    length -= left;
	    rest   =  0;
	}

	while(length > 63) {
	    transform(data, offset);
	    offset += 64;
	    length -= 64;
	}

	if(length > 0) {
	    System.arraycopy(data, offset, buffer, rest, length);
	    rest += length;
	}
    }

    protected final byte[] engineDigest() {
	byte[] buf = new byte[digestLength];
	try {
	    engineDigest(buf, 0, buf.length);
	} catch(DigestException e) {
	    /* Can't happen... */
	}
        return buf;
    }

    protected final int engineGetDigestLength() {
        return digestLength;
    }

    protected abstract void transform(byte data[], int offset);
    protected abstract MD512BitBlock cloneInternal();

}