md5.java

文件验证

package utils.md5;

import java.io.*;

/**
 * Fast implementation of RSA's MD5 hash generator in Java JDK Beta-2 or higher.
 * <p>
 * Originally written by Santeri Paavolainen, Helsinki Finland 1996.<br>
 * (c) Santeri Paavolainen, Helsinki Finland 1996<br>
 * Many changes Copyright (c) 2002 - 2008 Timothy W Macinta<br>
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 * <p>
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 * <p>
 * See http://www.twmacinta.com/myjava/fast_md5.php for more information
 * on this file and the related files.
 * <p>
 * This was originally a rather straight re-implementation of the
 * reference implementation given in RFC1321 by RSA.  It passes the MD5
 * test suite as defined in RFC1321.
 * <p>
 * Many optimizations made by Timothy W Macinta.  Reduced time to checksum a
 * test file in Java alone to roughly half the time taken compared with
 * java.security.MessageDigest (within an intepretter).  Also added an
 * optional native method to reduce the time even further.
 * See http://www.twmacinta.com/myjava/fast_md5.php for further information
 * on the time improvements achieved.
 * <p>
 * Some bug fixes also made by Timothy W Macinta.
 * <p>
 * Please note: I (Timothy Macinta) have put this code in the
 * com.twmacinta.util package only because it came without a package.  I
 * was not the the original author of the code, although I did
 * optimize it (substantially) and fix some bugs.
 * <p>
 * This Java class has been derived from the RSA Data Security, Inc. MD5 
 * Message-Digest Algorithm and its reference implementation.
 * <p>
 * This class will attempt to use a native method to quickly compute
 * checksums when the appropriate native library is available.  On Linux,
 * this library should be named "MD5.so" and on Windows it should be
 * named "MD5.dll".  The code will attempt to locate the library in the
 * following locations in the order given:
 *
 * <ol>
 *   <li>The path specified by the system property
 *       "com.twmacinta.util.MD5.NATIVE_LIB_FILE"
 *        (be sure to include "MD5.so" or "MD5.dll"
 *        as appropriate at the end of the path).
 *   <li>A platform specific directory beneath the "lib/arch/" directory.
 *       On Linux for x86, this is "lib/arch/linux_x86/".  On Windows for
 *       x86, this is "lib/arch/win32_x86/".
 *   <li>Within the "lib/" directory.
 *   <li>Within the current directory.
 * </ol>
 *
 * <p>
 * If the library is not found, the code will fall back to the default
 * (slower) Java code.
 * <p>
 * As a side effect of having the code search for the native library,
 * SecurityExceptions might be thrown on JVMs that have a restrictive
 * SecurityManager.  The initialization code attempts to silently discard
 * these exceptions and continue, but many SecurityManagers will
 * attempt to notify the user directly of all SecurityExceptions thrown.
 * Consequently, the code has provisions for skipping the search for
 * the native library.  Any of these provisions may be used to skip the
 * search as long as they are performed <i>before</i> the first
 * instance of a com.twmacinta.util.MD5 object is constructed (note that
 * the convenience stream objects will implicitly create an MD5 object).
 * <p>
 * The first option is to set the system property
 * "com.twmacinta.util.MD5.NO_NATIVE_LIB" to "true" or "1".
 * Unfortunately, SecurityManagers may also choose to disallow system
 * property setting, so this won't be of use in all cases.
 * <p>
 * The second option is to call
 * com.twmacinta.util.MD5.initNativeLibrary(true) before any MD5 objects
 * are constructed.
 *
 * @author Santeri Paavolainen <[e-mail]>
 * @author Timothy W Macinta ([e-mail]) (optimizations and bug fixes)
 */

public class MD5 {
    
    /**
     * MD5 state
     **/
    MD5State state;
    
    /**
     * If Final() has been called, finals is set to the current finals
     * state. Any Update() causes this to be set to null.
     **/
    MD5State finals;
    
    /** 
     * Padding for Final()
     **/
    static byte 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
    };
    
    private static boolean native_lib_loaded = false;
    private static boolean native_lib_init_pending = true;
    
    /**
     * Initialize MD5 internal state (object can be reused just by
     * calling Init() after every Final()
     **/
    public synchronized void Init () {
        state = new MD5State();
        finals = null;
    }
    
    /**
     * Class constructor
     **/
    public MD5 () {
        if (native_lib_init_pending) _initNativeLibrary();
        this.Init();
    }
    
    /**
     * Initialize class, and update hash with ob.toString()
     *
     * @param ob Object, ob.toString() is used to update hash
     *           after initialization
     **/
    public MD5 (Object ob) {
        this();
        Update(ob.toString());
    }
    
    private void Decode (byte buffer[], int shift, int[] out) {
        /*len += shift;
        for (int i = 0; shift < len; i++, shift += 4) {
            out[i] = ((int) (buffer[shift] & 0xff)) |
                (((int) (buffer[shift + 1] & 0xff)) << 8) |
                (((int) (buffer[shift + 2] & 0xff)) << 16) |
                (((int)  buffer[shift + 3]) << 24);
        }*/
        
        // unrolled loop (original loop shown above)
        
        out[0] = ((int) (buffer[shift] & 0xff)) |
            (((int) (buffer[shift + 1] & 0xff)) << 8) |
            (((int) (buffer[shift + 2] & 0xff)) << 16) |
            (((int)  buffer[shift + 3]) << 24);
        out[1] = ((int) (buffer[shift + 4] & 0xff)) |
            (((int) (buffer[shift + 5] & 0xff)) << 8) |
            (((int) (buffer[shift + 6] & 0xff)) << 16) |
            (((int)  buffer[shift + 7]) << 24);
        out[2] = ((int) (buffer[shift + 8] & 0xff)) |
            (((int) (buffer[shift + 9] & 0xff)) << 8) |
            (((int) (buffer[shift + 10] & 0xff)) << 16) |
            (((int)  buffer[shift + 11]) << 24);
        out[3] = ((int) (buffer[shift + 12] & 0xff)) |
            (((int) (buffer[shift + 13] & 0xff)) << 8) |
            (((int) (buffer[shift + 14] & 0xff)) << 16) |
            (((int)  buffer[shift + 15]) << 24);
        out[4] = ((int) (buffer[shift + 16] & 0xff)) |
            (((int) (buffer[shift + 17] & 0xff)) << 8) |
            (((int) (buffer[shift + 18] & 0xff)) << 16) |
            (((int)  buffer[shift + 19]) << 24);
        out[5] = ((int) (buffer[shift + 20] & 0xff)) |
            (((int) (buffer[shift + 21] & 0xff)) << 8) |
            (((int) (buffer[shift + 22] & 0xff)) << 16) |
            (((int)  buffer[shift + 23]) << 24);
        out[6] = ((int) (buffer[shift + 24] & 0xff)) |
            (((int) (buffer[shift + 25] & 0xff)) << 8) |
            (((int) (buffer[shift + 26] & 0xff)) << 16) |
            (((int)  buffer[shift + 27]) << 24);
        out[7] = ((int) (buffer[shift + 28] & 0xff)) |
            (((int) (buffer[shift + 29] & 0xff)) << 8) |
            (((int) (buffer[shift + 30] & 0xff)) << 16) |
            (((int)  buffer[shift + 31]) << 24);
        out[8] = ((int) (buffer[shift + 32] & 0xff)) |
            (((int) (buffer[shift + 33] & 0xff)) << 8) |
            (((int) (buffer[shift + 34] & 0xff)) << 16) |
            (((int)  buffer[shift + 35]) << 24);
        out[9] = ((int) (buffer[shift + 36] & 0xff)) |
            (((int) (buffer[shift + 37] & 0xff)) << 8) |
            (((int) (buffer[shift + 38] & 0xff)) << 16) |
            (((int)  buffer[shift + 39]) << 24);
        out[10] = ((int) (buffer[shift + 40] & 0xff)) |
            (((int) (buffer[shift + 41] & 0xff)) << 8) |
            (((int) (buffer[shift + 42] & 0xff)) << 16) |
            (((int)  buffer[shift + 43]) << 24);
        out[11] = ((int) (buffer[shift + 44] & 0xff)) |
            (((int) (buffer[shift + 45] & 0xff)) << 8) |
            (((int) (buffer[shift + 46] & 0xff)) << 16) |
            (((int)  buffer[shift + 47]) << 24);
        out[12] = ((int) (buffer[shift + 48] & 0xff)) |
            (((int) (buffer[shift + 49] & 0xff)) << 8) |
            (((int) (buffer[shift + 50] & 0xff)) << 16) |
            (((int)  buffer[shift + 51]) << 24);
        out[13] = ((int) (buffer[shift + 52] & 0xff)) |
            (((int) (buffer[shift + 53] & 0xff)) << 8) |
            (((int) (buffer[shift + 54] & 0xff)) << 16) |
            (((int)  buffer[shift + 55]) << 24);
        out[14] = ((int) (buffer[shift + 56] & 0xff)) |
            (((int) (buffer[shift + 57] & 0xff)) << 8) |
            (((int) (buffer[shift + 58] & 0xff)) << 16) |
            (((int)  buffer[shift + 59]) << 24);
        out[15] = ((int) (buffer[shift + 60] & 0xff)) |
            (((int) (buffer[shift + 61] & 0xff)) << 8) |
            (((int) (buffer[shift + 62] & 0xff)) << 16) |
            (((int)  buffer[shift + 63]) << 24);
    }
    
    private native void Transform_native (int[] state, byte buffer[], int shift, int length);
    
    private void Transform (MD5State state, byte buffer[], int shift, int[] decode_buf) {
        int
            a = state.state[0],
            b = state.state[1],
            c = state.state[2],
            d = state.state[3],
            x[] = decode_buf;
        
        Decode(buffer, shift, decode_buf);
        
        /* Round 1 */
        a += ((b & c) | (~b & d)) + x[ 0] + 0xd76aa478; /* 1 */
        a = ((a << 7) | (a >>> 25)) + b;
        d += ((a & b) | (~a & c)) + x[ 1] + 0xe8c7b756; /* 2 */
        d = ((d << 12) | (d >>> 20)) + a;
        c += ((d & a) | (~d & b)) + x[ 2] + 0x242070db; /* 3 */
        c = ((c << 17) | (c >>> 15)) + d;
        b += ((c & d) | (~c & a)) + x[ 3] + 0xc1bdceee; /* 4 */
        b = ((b << 22) | (b >>> 10)) + c;
        
        a += ((b & c) | (~b & d)) + x[ 4] + 0xf57c0faf; /* 5 */
        a = ((a << 7) | (a >>> 25)) + b;
        d += ((a & b) | (~a & c)) + x[ 5] + 0x4787c62a; /* 6 */
        d = ((d << 12) | (d >>> 20)) + a;
        c += ((d & a) | (~d & b)) + x[ 6] + 0xa8304613; /* 7 */
        c = ((c << 17) | (c >>> 15)) + d;
        b += ((c & d) | (~c & a)) + x[ 7] + 0xfd469501; /* 8 */
        b = ((b << 22) | (b >>> 10)) + c;
        
        a += ((b & c) | (~b & d)) + x[ 8] + 0x698098d8; /* 9 */
        a = ((a << 7) | (a >>> 25)) + b;
        d += ((a & b) | (~a & c)) + x[ 9] + 0x8b44f7af; /* 10 */
        d = ((d << 12) | (d >>> 20)) + a;
        c += ((d & a) | (~d & b)) + x[10] + 0xffff5bb1; /* 11 */
        c = ((c << 17) | (c >>> 15)) + d;
        b += ((c & d) | (~c & a)) + x[11] + 0x895cd7be; /* 12 */
        b = ((b << 22) | (b >>> 10)) + c;
        
        a += ((b & c) | (~b & d)) + x[12] + 0x6b901122; /* 13 */
        a = ((a << 7) | (a >>> 25)) + b;
        d += ((a & b) | (~a & c)) + x[13] + 0xfd987193; /* 14 */
        d = ((d << 12) | (d >>> 20)) + a;
        c += ((d & a) | (~d & b)) + x[14] + 0xa679438e; /* 15 */
        c = ((c << 17) | (c >>> 15)) + d;
        b += ((c & d) | (~c & a)) + x[15] + 0x49b40821; /* 16 */
        b = ((b << 22) | (b >>> 10)) + c;
        
        
        /* Round 2 */