MD5加密算法的使用

在注册用户的时候：      String MD5Pass = MD5.toMD5(user.getUserPass());      user.setUserPass(MD5Pass);      ......  在用户登录比较的时候：      if(userDB.getUserPass().equals(MD5.toMD5(userPass)))      ......      package ecp.util ;  public class MD5 {     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 };     /* 下面的三个成员是MD5计算过程中用到的3个核心数据，在原始的C实现中     被定义到MD5_CTX结构中     */     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是MD5的唯一一个公共成员，是最新一次计算结果的     16进制ASCII表示.     */     public String digestHexStr;     /* digest,是最新一次计算结果的2进制内部表示，表示128bit的MD5值.     */     private byte[] digest = new byte[16];     /*     getMD5ofStr是类MD5最主要的公共方法，入口参数是你想要进行MD5变换的字符串     返回的是变换完的结果，这个结果是从公共成员digestHexStr取得的．     */     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;     }     // 这是MD5这个类的标准构造函数，JavaBean要求有一个public的并且没有参数的构造函数     public MD5() {        md5Init();        return;     }     /* md5Init是一个初始化函数，初始化核心变量，装入标准的幻数 */     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 是4个基本的MD5函数，在原始的MD5的C实现中，由于它们是      简单的位运算，可能出于效率的考虑把它们实现成了宏，在java中，我们把它们      实现成了private方法，名字保持了原来C中的。 */     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和II将调用F,G,H,I进行近一步变换     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是MD5的主计算过程，inbuf是要变换的字节串，inputlen是长度，这个     函数由getMD5ofStr调用，调用之前需要调用md5init，因此把它设计成private的     */     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);     }     /*     md5Final整理和填写输出结果     */     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);     }     /* md5Memcpy是一个内部使用的byte数组的块拷贝函数，从input的inpos开始把len长度的     字节拷贝到output的outpos位置开始      */     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是MD5核心变换程序，有md5Update调用，block是分块的原始字节     */     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把long数组按顺序拆成byte数组，因为java的long类型是64bit的，     只拆低32bit，以适应原始C实现的用途     */     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把byte数组按顺序合成成long数组，因为java的long类型是64bit的，     只合成低32bit，高32bit清零，以适应原始C实现的用途     */     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;     }     /*     b2iu是我写的一个把byte按照不考虑正负号的原则的＂升位＂程序，因为java没有unsigned运算     */     public static long b2iu(byte b) {        return b < 0 ? b & 0x7F + 128 : b;     }     /*byteHEX()，用来把一个byte类型的数转换成十六进制的ASCII表示，     因为java中的byte的toString无法实现这一点，我们又没有C语言中的     sprintf(outbuf,"%02X",ib)     */     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;     }   //加密     public static String toMD5(String source) {        MD5 md5 = new MD5();        return md5.getMD5ofStr(source).toLowerCase();     }  }