最快的MD5

      

       第一次接触MD5算法是在2001年，当时在网上找了下，下载如下java源代码，没有import从最底层给出了MD5算法是如何实现的，可以彻底了解下一个加密算法是如何构建的，很有意思：

public class MD5 {

    /* implemented by #define in c */

    static final int S11 = 7;

 

    static final int S12 = 12;

 

    static final int S13 = 17;

 

    static final int S14 = 22;

 

    static final int S21 = 5;

 

    static final int S22 = 9;

 

    static final int S23 = 14;

 

    static final int S24 = 20;

 

    static final int S31 = 4;

 

    static final int S32 = 11;

 

    static final int S33 = 16;

 

    static final int S34 = 23;

 

    static final int S41 = 6;

 

    static final int S42 = 10;

 

    static final int S43 = 15;

 

    static final int S44 = 21;

 

    static final byte[] PADDING = { -128, 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 };

 

    // core data while process md5, definition in MD5_CTX in origin C

    private long[] state = new long[4]; // state (ABCD)

 

    private long[] count = new long[2]; // number of bits, modulo 2^64 (lsb

                                   // first)

 

    private byte[] buffer = new byte[64]; // input buffer

 

    // digestHexStr was the only public member of MD5?lasted result in 16bit

    // ascii form

 

    public String digestHexStr;

 

    // digest, latest process result, show the 128bit of MD5 value

 

    private byte[] digest = new byte[16];

 

    // mainly public method, parameter was the source string, return the result

    // 128bit md5 string

    public String getMD5ofStr(String inbuf) {

       md5Init();

       md5Update(inbuf.getBytes(), inbuf.length());

       md5Final();

       digestHexStr = "";

       for (int i = 0; i < 16; i++) {

           digestHexStr += byteHEX(digest[i]);

       }

       return digestHexStr;

 

    }

 

    public MD5() {

       md5Init();

 

       return;

    }

 

    private void md5Init() {

       count[0] = 0L;

       count[1] = 0L;

       // /* Load magic initialization constants.

 

       state[0] = 0x67452301L;

       state[1] = 0xefcdab89L;

       state[2] = 0x98badcfeL;

       state[3] = 0x10325476L;

 

       return;

    }

 

    /*

     * F, G, H ,I was 4 basic functions in MD5, in implemented method of origin

     * C, because they are simple bit process????????????????????java???????

     * ??????private??????????C???

     */

 

    private long F(long x, long y, long z) {

       return (x & y) | ((~x) & z);

 

    }

 

    private long G(long x, long y, long z) {

       return (x & z) | (y & (~z));

 

    }

 

    private long H(long x, long y, long z) {

       return x ^ y ^ z;

    }

 

    private long I(long x, long y, long z) {

       return y ^ (x | (~z));

    }

 

    /*

     * FF,GG,HH?II???F,G,H,I??????? FF, GG, HH, and II transformations for

     * rounds 1, 2, 3, and 4. Rotation is separate from addition to prevent

     * recomputation.

     */

 

    private long FF(long a, long b, long c, long d, long x, long s, long ac) {

       a += F(b, c, d) + x + ac;

       a = ((int) a << s) | ((int) a >>> (32 - s));

       a += b;

       return a;

    }

 

    private long GG(long a, long b, long c, long d, long x, long s, long ac) {

       a += G(b, c, d) + x + ac;

       a = ((int) a << s) | ((int) a >>> (32 - s));

       a += b;

       return a;

    }

 

    private long HH(long a, long b, long c, long d, long x, long s, long ac) {

       a += H(b, c, d) + x + ac;

       a = ((int) a << s) | ((int) a >>> (32 - s));

       a += b;

       return a;

    }

 

    private long II(long a, long b, long c, long d, long x, long s, long ac) {

       a += I(b, c, d) + x + ac;

       a = ((int) a << s) | ((int) a >>> (32 - s));

       a += b;

       return a;

    }

 

    /*

     * md5Update?MD5???????inbuf?????????inputlen??????

     * ???getMD5ofStr???????????md5init????????private?

     */

    private void md5Update(byte[] inbuf, int inputLen) {

 

       int i, index, partLen;

       byte[] block = new byte[64];

       index = (int) (count[0] >>> 3) & 0x3F;

       // /* Update number of bits */

       if ((count[0] += (inputLen << 3)) < (inputLen << 3))

           count[1]++;

       count[1] += (inputLen >>> 29);

 

       partLen = 64 - index;

 

       // Transform as many times as possible.

       if (inputLen >= partLen) {

           md5Memcpy(buffer, inbuf, index, 0, partLen);

           md5Transform(buffer);

 

           for (i = partLen; i + 63 < inputLen; i += 64) {

 

              md5Memcpy(block, inbuf, 0, i, 64);

              md5Transform(block);

           }

           index = 0;

 

       } else

 

           i = 0;

 

       // /* Buffer remaining input */

       md5Memcpy(buffer, inbuf, index, i, inputLen - i);

 

    }

 

    private void md5Final() {

       byte[] bits = new byte[8];

       int index, padLen;

 

       // /* Save number of bits */

       Encode(bits, count, 8);

 

       // /* Pad out to 56 mod 64.

       index = (int) (count[0] >>> 3) & 0x3f;

       padLen = (index < 56) ? (56 - index) : (120 - index);

       md5Update(PADDING, padLen);

 

       // /* Append length (before padding) */

       md5Update(bits, 8);

 

       // /* Store state in digest */

       Encode(digest, state, 16);

 

    }

 

    private void md5Memcpy(byte[] output, byte[] input, int outpos, int inpos,

           int len) {

       int i;

 

       for (i = 0; i < len; i++)

           output[outpos + i] = input[inpos + i];

    }

 

    /*

     * md5Transform?MD5????????md5Update???block????????

     */

    private void md5Transform(byte block[]) {

       long a = state[0], b = state[1], c = state[2], d = state[3];

       long[] x = new long[16];

 

       Decode(x, block, 64);

 

       /* Round 1 */

       a = FF(a, b, c, d, x[0], S11, 0xd76aa478L); /* 1 */

       d = FF(d, a, b, c, x[1], S12, 0xe8c7b756L); /* 2 */

       c = FF(c, d, a, b, x[2], S13, 0x242070dbL); /* 3 */

       b = FF(b, c, d, a, x[3], S14, 0xc1bdceeeL); /* 4 */

       a = FF(a, b, c, d, x[4], S11, 0xf57c0fafL); /* 5 */

       d = FF(d, a, b, c, x[5], S12, 0x4787c62aL); /* 6 */

       c = FF(c, d, a, b, x[6], S13, 0xa8304613L); /* 7 */

       b = FF(b, c, d, a, x[7], S14, 0xfd469501L); /* 8 */

       a = FF(a, b, c, d, x[8], S11, 0x698098d8L); /* 9 */

       d = FF(d, a, b, c, x[9], S12, 0x8b44f7afL); /* 10 */

       c = FF(c, d, a, b, x[10], S13, 0xffff5bb1L); /* 11 */

       b = FF(b, c, d, a, x[11], S14, 0x895cd7beL); /* 12 */

       a = FF(a, b, c, d, x[12], S11, 0x6b901122L); /* 13 */

       d = FF(d, a, b, c, x[13], S12, 0xfd987193L); /* 14 */

       c = FF(c, d, a, b, x[14], S13, 0xa679438eL); /* 15 */

       b = FF(b, c, d, a, x[15], S14, 0x49b40821L); /* 16 */

 

       /* Round 2 */

       a = GG(a, b, c, d, x[1], S21, 0xf61e2562L); /* 17 */

       d = GG(d, a, b, c, x[6], S22, 0xc040b340L); /* 18 */

       c = GG(c, d, a, b, x[11], S23, 0x265e5a51L); /* 19 */

       b = GG(b, c, d, a, x[0], S24, 0xe9b6c7aaL); /* 20 */

       a = GG(a, b, c, d, x[5], S21, 0xd62f105dL); /* 21 */

       d = GG(d, a, b, c, x[10], S22, 0x2441453L); /* 22 */

       c = GG(c, d, a, b, x[15], S23, 0xd8a1e681L); /* 23 */

       b = GG(b, c, d, a, x[4], S24, 0xe7d3fbc8L); /* 24 */

       a = GG(a, b, c, d, x[9], S21, 0x21e1cde6L); /* 25 */

       d = GG(d, a, b, c, x[14], S22, 0xc33707d6L); /* 26 */

       c = GG(c, d, a, b, x[3], S23, 0xf4d50d87L); /* 27 */

       b = GG(b, c, d, a, x[8], S24, 0x455a14edL); /* 28 */

       a = GG(a, b, c, d, x[13], S21, 0xa9e3e905L); /* 29 */

       d = GG(d, a, b, c, x[2], S22, 0xfcefa3f8L); /* 30 */

       c = GG(c, d, a, b, x[7], S23, 0x676f02d9L); /* 31 */

       b = GG(b, c, d, a, x[12], S24, 0x8d2a4c8aL); /* 32 */

 

       /* Round 3 */

       a = HH(a, b, c, d, x[5], S31, 0xfffa3942L); /* 33 */

       d = HH(d, a, b, c, x[8], S32, 0x8771f681L); /* 34 */

       c = HH(c, d, a, b, x[11], S33, 0x6d9d6122L); /* 35 */

       b = HH(b, c, d, a, x[14], S34, 0xfde5380cL); /* 36 */

       a = HH(a, b, c, d, x[1], S31, 0xa4beea44L); /* 37 */

       d = HH(d, a, b, c, x[4], S32, 0x4bdecfa9L); /* 38 */

       c = HH(c, d, a, b, x[7], S33, 0xf6bb4b60L); /* 39 */

       b = HH(b, c, d, a, x[10], S34, 0xbebfbc70L); /* 40 */

       a = HH(a, b, c, d, x[13], S31, 0x289b7ec6L); /* 41 */

       d = HH(d, a, b, c, x[0], S32, 0xeaa127faL); /* 42 */

       c = HH(c, d, a, b, x[3], S33, 0xd4ef3085L); /* 43 */

       b = HH(b, c, d, a, x[6], S34, 0x4881d05L); /* 44 */

       a = HH(a, b, c, d, x[9], S31, 0xd9d4d039L); /* 45 */

       d = HH(d, a, b, c, x[12], S32, 0xe6db99e5L); /* 46 */

       c = HH(c, d, a, b, x[15], S33, 0x1fa27cf8L); /* 47 */

       b = HH(b, c, d, a, x[2], S34, 0xc4ac5665L); /* 48 */

 

       /* Round 4 */

       a = II(a, b, c, d, x[0], S41, 0xf4292244L); /* 49 */

       d = II(d, a, b, c, x[7], S42, 0x432aff97L); /* 50 */

       c = II(c, d, a, b, x[14], S43, 0xab9423a7L); /* 51 */

       b = II(b, c, d, a, x[5], S44, 0xfc93a039L); /* 52 */

       a = II(a, b, c, d, x[12], S41, 0x655b59c3L); /* 53 */

       d = II(d, a, b, c, x[3], S42, 0x8f0ccc92L); /* 54 */

       c = II(c, d, a, b, x[10], S43, 0xffeff47dL); /* 55 */

       b = II(b, c, d, a, x[1], S44, 0x85845dd1L); /* 56 */

       a = II(a, b, c, d, x[8], S41, 0x6fa87e4fL); /* 57 */

       d = II(d, a, b, c, x[15], S42, 0xfe2ce6e0L); /* 58 */

       c = II(c, d, a, b, x[6], S43, 0xa3014314L); /* 59 */

       b = II(b, c, d, a, x[13], S44, 0x4e0811a1L); /* 60 */

       a = II(a, b, c, d, x[4], S41, 0xf7537e82L); /* 61 */

       d = II(d, a, b, c, x[11], S42, 0xbd3af235L); /* 62 */

       c = II(c, d, a, b, x[2], S43, 0x2ad7d2bbL); /* 63 */

       b = II(b, c, d, a, x[9], S44, 0xeb86d391L); /* 64 */

 

       state[0] += a;

       state[1] += b;

       state[2] += c;

       state[3] += d;

 

    }

 

    /*

     * Encode?long???????byte?????java?long???64bit?? ???32bit??????C?????

     */

    private void Encode(byte[] output, long[] input, int len) {

       int i, j;

 

       for (i = 0, j = 0; j < len; i++, j += 4) {

           output[j] = (byte) (input[i] & 0xffL);

           output[j + 1] = (byte) ((input[i] >>> 8) & 0xffL);

           output[j + 2] = (byte) ((input[i] >>> 16) & 0xffL);

           output[j + 3] = (byte) ((input[i] >>> 24) & 0xffL);

       }

    }

 

    /*

     * Decode?byte????????long?????java?long???64bit??

     * ????32bit??32bit????????C?????

     */

    private void Decode(long[] output, byte[] input, int len) {

       int i, j;

 

       for (i = 0, j = 0; j < len; i++, j += 4)

           output[i] = b2iu(input[j]) | (b2iu(input[j + 1]) << 8)

                  | (b2iu(input[j + 2]) << 16) | (b2iu(input[j + 3]) << 24);

 

       return;

    }

 

    public static long b2iu(byte b) {

       return b < 0 ? b & 0x7F + 128 : b;

    }

 

    public static String byteHEX(byte ib) {

       char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A',

              'B', 'C', 'D', 'E', 'F' };

       char[] ob = new char[2];

       ob[0] = Digit[(ib >>> 4) & 0X0F];

       ob[1] = Digit[ib & 0X0F];

       String s = new String(ob);

       return s;

    }

}

 

使用方式：new MD5().getMD5ofStr("your str");

最近，看到别人借助java.security.*工具包，写就如下MD5算法:

 

import java.security.*;

 

public class StringUtil {

    private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",

           "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

 

    /**

     * 转换字节数组为16进制字串

     *

     * @param b

     *            字节数组

     * @return 16进制字串

     */

 

    private static String byteArrayToHexString(byte[] b) {

       StringBuffer resultSb = new StringBuffer();

       for (int i = 0; i < b.length; i++) {

           resultSb.append(byteToHexString(b[i]));

       }

       return resultSb.toString();

    }

 

    private static String byteToHexString(byte b) {

       int n = b;

       if (n < 0) {

           n = 256 + n;

       }

       int d1 = n / 16;

       int d2 = n % 16;

       return hexDigits[d1] + hexDigits[d2];

    }

 

    public static String MD5Encode(String origin) {

       String resultString = null;

 

       try {

           resultString = new String(origin);

           MessageDigest md = MessageDigest.getInstance("MD5");

           resultString = byteArrayToHexString(md.digest(resultString

                  .getBytes()));

       } catch (Exception ex) {

 

       }

       return resultString;

    }

}

 

既然有现成的MessageDigest可用，为啥还搞得如上那么复杂呢？使用以下方式重写：

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

 

public class SuperMD5 {

 

    public static String encrypt(String inStr) throws Exception {

       MessageDigest md = null;

       String out = null;

 

       try {

           md = MessageDigest.getInstance("MD5");

           byte[] digest = md.digest(inStr.getBytes());

           out = byte2hex(digest);

       } catch (NoSuchAlgorithmException e) {

           e.printStackTrace();

           throw e;

       }

 

       return out;

    }

 

    private static String byte2hex(byte[] b) {

       String hs = "";

       String stmp = "";

       for (int n = 0; n < b.length; n++) {

           stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));

           if (stmp.length() == 1) {

              hs = hs + "0" + stmp;

           } else {

              hs = hs + stmp;

           }

       }

       return hs.toUpperCase();

    }

}

 

经测试，第二种方式性能最差，第一种次之，最后一种速度最快。