MD5算法的java版本

package DPS.AuthCom.Radius;

/*************************************************
md5 类实现了RSA Data Security, Inc.在提交给IETF
的RFC1321中的MD5 message-digest 算法。
*************************************************/
public class MD55
{
  /* 下面这些S11-S44实际上是一个4*4的矩阵,在原始的C实现中是用#define 实现的,
    这里把它们实现成为static final是表示了只读,切能在同一个进程空间内的多个
    Instance间共享*/
  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 MD55()
  {
    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;
  }
  /**
   * getMD5ofBye
   *
   * @param inbuf byte[]
   * @return byte[]
   */
  public byte[] getMD5ofBye(byte[] inbuf)
  {
    md5Init();
    md5Update(inbuf, inbuf.length);
    md5Final();
    digestHexStr = "";    
   for (int i = 0; i < 16; i++)
    {
      digestHexStr += byteHEX(digest[i]);    
    }
    return digestHexStr.getBytes();
  }
}
 
注:如果有人使用过这个版本的MD5算法,会发现和c的返回值不一样,是因为c返回的是一个char*的指针,而java并没有指针,和c程序在内存中的值明显对不上,即使把最后一个方法getMD5ofBye的返回值改成char[]还是达不到目的,而且你会看到c内存中返回值的一个字节是java内存中返回值的两个字节合在一起的值,举个例子:比如说c中的返回值是char a[0] ='0x12',而java中返回值则是char b[0] = '0x01',b[1] = '0x02'。要怎么改变这种在内存中返回值不同的情况?你可以把byteHEX方法完全注释掉,换成下面这个方法:
public static byte byteHEX(byte ib)
  {
        return ib;
  }
并且把getMD5ofBye方法稍作修改,即改成:
public byte[] getMD5ofBye(byte[] inbuf)
  {
    md5Init();
    md5Update(inbuf, inbuf.length);
    md5Final();
    byte digestHexStr;
    byte b[] = new byte[16];//大小根据需要自己定;
    for (int i = 0; i < 16; i++)
    {
      digestHexStr += byteHEX(digest[i]);
      b[i] = digestHexStr ;
    }
    return b;
  }

经过这样的处理后,java版本的MD5算法就和c版本的MD5算法在返回值上完全一致了。

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