/**
* @(#)MD5.java
*
*
* @SuLyin
* @version 1.00 2008/10/6
*/
package com.sulyin.ustbphone;

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 };
  
   /* 计算过程中的三个核心数据 */
   private long[] state = new long[ 4 ];
   private long[] count = new long[ 2 ];
   private byte[] buffer = new byte[ 64 ];
  
   /* 最新一次计算结果的16进制ASCII表示（公共成员-digestHexStr）*/
   public String digestHexStr;
  
   /* 最新一次计算结果的二进制内部表示，表示128位的MD5值（私有成员-digest）*/
   private byte[] digest = new byte[ 16 ];
  
   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;
    state[ 0 ] = 0x67452301L;
    state[ 1 ] = 0xefcdab89L;
    state[ 2 ] = 0x98badcfeL;
    state[ 3 ] = 0x10325476L;
    return;
    }
   
    /* F,G,H,I四个基本的MD5函数，实现简单的位运算。*/
    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进行进一步变换 */
    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是它的长度，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;
    if( ( count[ 0 ] += ( inputLen << 3 ) ) < ( inputLen << 3 ) )
       count[ 1 ] ++;
    count[ 1 ] += ( inputLen >>> 29 );
    partLen = 64 - index;
    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;
    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;
    Encode( bits, count, 8 );
    index = ( int )( count[ 0 ] >>> 3 ) & 0x3f;
    padLen = ( index < 56 ) ? ( 56 - index ) : ( 120 - index );
    md5Update( PADDING, padLen );
    md5Update( bits, 8 );
    Encode( digest, state, 16 );
    }
   
    /* md5Memcopy是一个内部使用的byte数组的块复制函数，从input的inpos开始把len长度的字节复制到ouput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 + 1 ] = input[ inpos + 1 ];
    }
    }
    /* md5Transform是md5的核心变换程序，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64位的，所以只拆低32位，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long数组，因为java的long类型是64位的，因此只合成低32位，高32位清零 */
    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 );
    }
    }
   
    /* b2iu是一个附加的把byte按照不考虑正负号的原则的“升位”函数，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toString方法无法做到这一点 */
    public static String byteHEX( byte ib )
    {
    char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', '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 String toMD5( String source )
    {
    MD5 md5 = new MD5();
    return md5.getMD5ofStr( source );
    }
}