JAVA MD5 加密代碼

public class MD5 {   
  /* 下面這些S11-S44實際上是一個4*4的矩陣，在原始的C實現中是用#define 實現的，  
  這裏把它們實現成爲static final是表示了只讀，切能在同一個進程空間內的多個  
  Instance間共享*/  
    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 };   
    /* 下面的三個成員是MD5計算過程中用到的3個核心數據，在原始的C實現中  
      被定義到MD5_CTX結構中  
     
      */  
    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的唯一一個公共成員，是最新一次計算結果的  
  　 16進制ASCII表示.  
  */  
    public String digestHexStr;   
      
    /* digest,是最新一次計算結果的2進制內部表示，表示128bit的MD5值.  
  */  
    private byte[] digest = new byte[16];   
      
  /*  
    getMD5ofStr是類MD5最主要的公共方法，入口參數是你想要進行MD5變換的字符串  
    返回的是變換完的結果，這個結果是從公共成員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;   
  
    }   
    // 這是MD5這個類的標準構造函數，JavaBean要求有一個public的並且沒有參數的構造函數   
    public MD5() {   
          md5Init();   
  
          return;   
    }   
    /* md5Init是一個初始化函數，初始化核心變量，裝入標準的幻數 */  
    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個基本的MD5函數，在原始的MD5的C實現中，由於它們是   
    簡單的位運算，可能出於效率的考慮把它們實現成了宏，在java中，我們把它們   
  　　實現成了private方法，名字保持了原來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將調用F,G,H,I進行近一步變換  
      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的主計算過程，inbuf是要變換的字節串，inputlen是長度，這個  
      函數由getMD5ofStr調用，調用之前需要調用md5init，因此把它設計成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整理和填寫輸出結果  
    */  
    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是一個內部使用的byte數組的塊拷貝函數，從input的inpos開始把len長度的  
　　　　　 字節拷貝到output的outpos位置開始  
    */  
  
    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核心變換程序，有md5Update調用，block是分塊的原始字節  
    */  
    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數組按順序拆成byte數組，因爲java的long類型是64bit的，  
      只拆低32bit，以適應原始C實現的用途  
    */  
    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數組按順序合成成long數組，因爲java的long類型是64bit的，  
      只合成低32bit，高32bit清零，以適應原始C實現的用途  
    */  
    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是我寫的一個把byte按照不考慮正負號的原則的＂升位＂程序，因爲java沒有unsigned運算  
    */  
    public static long b2iu(byte b) {   
          return b < 0 ? b & 0x7F + 128 : b;   
    }   
      
  /*byteHEX()，用來把一個byte類型的數轉換成十六進制的ASCII表示，  
  　因爲java中的byte的toString無法實現這一點，我們又沒有C語言中的  
    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;   
    }   
    public static void main(String args[]){   
        MD5 md5 = new MD5();   
        System.out.println(md5.getMD5ofStr("12345"));   
    }   
}