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求助版主及各位高手！我有段MD5的代码看不懂，求助！

yingxue6666

发贴: 13
积分: 0

于 2005-06-01 09:48

我下个星期就要答辩了，但是这段代码始终读不懂，请版主及各位高手指点一下，我的QQ是15944866，谢谢了，万分感谢！
package yang;

public class MD5
{
  String hex_chr = "0123456789abcdef";
  private String rhex(int num)
  {
    String str = "";
    for(int j = 0; j <= 3; j++)
    str = str + hex_chr.charAt((num >> (j * 8 + 4)) & 0x0F) + hex_chr.charAt((num >> (j * 8)) & 0x0F);
    return str;
  }

  private int[] str2blks_MD5(String str)
  {
    int nblk = ((str.length() + 8) >> 6) + 1;
    int[] blks = new int[nblk * 16];
    int i = 0;
    for(i = 0; i < nblk * 16; i++) {
      blks[i] = 0;
    }
    for(i = 0; i < str.length(); i++) {
      blks[i >> 2] |= str.charAt Light Bulb

<< ((i % 4) * 8);
    }
    blks[i >> 2] |= 0x80 << ((i % 4) * 8);
    blks[nblk * 16 - 2] = str.length()*8;

    return blks;
  }

  private int add(int x, int y)
  {
    return ((x&0x7FFFFFFF) + (y&0x7FFFFFFF)) ^ (x&0x80000000) ^ (y&0x80000000);
  }

  private int rol(int num, int cnt)
  {
    return (num << cnt) | (num >>> (32 - cnt));
  }

  private int cmn(int q, int a, int b, int x, int s, int t)
  {
    return add(rol(add(add(a, q), add(x, t)), s), b);
  }
  private int ff(int a, int b, int c, int d, int x, int s, int t)
  {
    return cmn((b & c) | ((~b) & d), a, b, x, s, t);
  }
  private int gg(int a, int b, int c, int d, int x, int s, int t)
  {
    return cmn((b & d) | (c & (~d)), a, b, x, s, t);
  }
  private int hh(int a, int b, int c, int d, int x, int s, int t)
  {
    return cmn(b ^ c ^ d, a, b, x, s, t);
  }
  private int ii(int a, int b, int c, int d, int x, int s, int t)
  {
    return cmn(c ^ (b | (~d)), a, b, x, s, t);
  }

  public String calcMD5(String str)
  {
  int[] x = str2blks_MD5(str);
  int a = 0x67452301;
  int b = 0xEFCDAB89;
  int c = 0x98BADCFE;
  int d = 0x10325476;

  for(int i = 0; i < x.length; i += 16)
  {
  int olda = a;
  int oldb = b;
  int oldc = c;
  int oldd = d;

  a = ff(a, b, c, d, x[i+ 0], 7 , 0xD76AA478);
  d = ff(d, a, b, c, x[i+ 1], 12, 0xE8C7B756);
  c = ff(c, d, a, b, x[i+ 2], 17, 0x242070D Black Eye

;
  b = ff(b, c, d, a, x[i+ 3], 22, 0xC1BDCEEE);
  a = ff(a, b, c, d, x[i+ 4], 7 , 0xF57C0FAF);
  d = ff(d, a, b, c, x[i+ 5], 12, 0x4787C62A);
  c = ff(c, d, a, b, x[i+ 6], 17, 0xA8304613);
  b = ff(b, c, d, a, x[i+ 7], 22, 0xFD469501);
  a = ff(a, b, c, d, x[i+ 8], 7 , 0x69809 Cool

8);
  d = ff(d, a, b, c, x[i+ 9], 12, 0x8B44F7AF);
  c = ff(c, d, a, b, x[i+10], 17, 0xFFFF5BB1);
  b = ff(b, c, d, a, x[i+11], 22, 0x895CD7BE);
  a = ff(a, b, c, d, x[i+12], 7 , 0x6B901122);
  d = ff(d, a, b, c, x[i+13], 12, 0xFD987193);
  c = ff(c, d, a, b, x[i+14], 17, 0xA679438E);
  b = ff(b, c, d, a, x[i+15], 22, 0x49B40821);

  a = gg(a, b, c, d, x[i+ 1], 5 , 0xF61E2562);
  d = gg(d, a, b, c, x[i+ 6], 9 , 0xC040B340);
  c = gg(c, d, a, b, x[i+11], 14, 0x265E5A51);
  b = gg(b, c, d, a, x[i+ 0], 20, 0xE9B6C7AA);
  a = gg(a, b, c, d, x[i+ 5], 5 , 0xD62F105D);
  d = gg(d, a, b, c, x[i+10], 9 , 0x02441453);
  c = gg(c, d, a, b, x[i+15], 14, 0xD8A1E681);
  b = gg(b, c, d, a, x[i+ 4], 20, 0xE7D3FBC8);
  a = gg(a, b, c, d, x[i+ 9], 5 , 0x21E1CDE6);
  d = gg(d, a, b, c, x[i+14], 9 , 0xC33707D6);
  c = gg(c, d, a, b, x[i+ 3], 14, 0xF4D50D87);
  b = gg(b, c, d, a, x[i+ 8], 20, 0x455A14ED);
  a = gg(a, b, c, d, x[i+13], 5 , 0xA9E3E905);
  d = gg(d, a, b, c, x[i+ 2], 9 , 0xFCEFA3F8);
  c = gg(c, d, a, b, x[i+ 7], 14, 0x676F02D9);
  b = gg(b, c, d, a, x[i+12], 20, 0x Cool

2A4C8A);

  a = hh(a, b, c, d, x[i+ 5], 4 , 0xFFFA3942);
  d = hh(d, a, b, c, x[i+ 8], 11, 0x8771F681);
  c = hh(c, d, a, b, x[i+11], 16, 0x6D9D6122);
  b = hh(b, c, d, a, x[i+14], 23, 0xFDE5380C);
  a = hh(a, b, c, d, x[i+ 1], 4 , 0xA4BEEA44);
  d = hh(d, a, b, c, x[i+ 4], 11, 0x4BDECFA9);
  c = hh(c, d, a, b, x[i+ 7], 16, 0xF6BB4B60);
  b = hh(b, c, d, a, x[i+10], 23, 0xBEBFBC70);
  a = hh(a, b, c, d, x[i+13], 4 , 0x289B7EC6);
  d = hh(d, a, b, c, x[i+ 0], 11, 0xEAA127FA);
  c = hh(c, d, a, b, x[i+ 3], 16, 0xD4EF3085);
  b = hh(b, c, d, a, x[i+ 6], 23, 0x04881D05);
  a = hh(a, b, c, d, x[i+ 9], 4 , 0xD9D4D039);
  d = hh(d, a, b, c, x[i+12], 11, 0xE6DB99E5);
  c = hh(c, d, a, b, x[i+15], 16, 0x1FA27CF8);
  b = hh(b, c, d, a, x[i+ 2], 23, 0xC4AC5665);

  a = ii(a, b, c, d, x[i+ 0], 6 , 0xF4292244);
  d = ii(d, a, b, c, x[i+ 7], 10, 0x432AFF97);
  c = ii(c, d, a, b, x[i+14], 15, 0xAB9423A7);
  b = ii(b, c, d, a, x[i+ 5], 21, 0xFC93A039);
  a = ii(a, b, c, d, x[i+12], 6 , 0x655B59C3);
  d = ii(d, a, b, c, x[i+ 3], 10, 0x8F0CCC92);
  c = ii(c, d, a, b, x[i+10], 15, 0xFFEFF47D);
  b = ii(b, c, d, a, x[i+ 1], 21, 0x85845DD1);
  a = ii(a, b, c, d, x[i+ 8], 6 , 0x6FA87E4F);
  d = ii(d, a, b, c, x[i+15], 10, 0xFE2CE6E0);
  c = ii(c, d, a, b, x[i+ 6], 15, 0xA3014314);
  b = ii(b, c, d, a, x[i+13], 21, 0x4E0811A1);
  a = ii(a, b, c, d, x[i+ 4], 6 , 0xF7537E82);
  d = ii(d, a, b, c, x[i+11], 10, 0xBD3AF235);
  c = ii(c, d, a, b, x[i+ 2], 15, 0x2AD7D2B Black Eye

;
  b = ii(b, c, d, a, x[i+ 9], 21, 0xEB86D391);

  a = add(a, olda);
  b = add(b, oldb);
  c = add(c, oldc);
  d = add(d, oldd);
  }
  return rhex Angel

+ rhex

+ rhex

+ rhex

;
  }
  public static void main(String[] args)
  {
    MD5 md = new MD5();
    String str = md.calcMD5("123456");
    System.out.println(str);
  }
}

作者	Re:求助版主及各位高手！我有段MD5的代码看不懂，求助！ [Re:yingxue6666]
menzy 版主发贴: 754 积分: 113	于 2005-06-01 20:53 把源文件作为附件,并且注明哪里不明白

作者	Re:求助版主及各位高手！我有段MD5的代码看不懂，求助！ [Re:menzy]
yingxue6666 发贴: 13 积分: 0	于 2005-06-03 12:59 诚实的说，一句也看不懂，帮帮我吧 MD5程序代码.doc (37.5k)

作者	Re:求助版主及各位高手！我有段MD5的代码看不懂，求助！ [Re:menzy]
yingxue6666 发贴: 13 积分: 0	于 2005-06-03 13:11 红色的代码都不懂，帮帮我吧！！ MD5程序代码.doc (37.5k)

作者	Re:求助版主及各位高手！我有段MD5的代码看不懂，求助！ [Re:yingxue6666]
yingxue6666 发贴: 13 积分: 0	于 2005-06-03 13:12 zhshuang8888@163.com这是我的邮箱！先谢谢版主了！万分感激！！！

作者	Re:求助版主及各位高手！我有段MD5的代码看不懂，求助！ [Re:yingxue6666]
menzy 版主发贴: 754 积分: 113	于 2005-06-03 14:12 什么都不懂?那就没有办法了,我不可能给你逐行写注释啊你先看看MD5算法的基本实现原理和处理过程的说明，然后对照看吧。

作者	Re:求助版主及各位高手！我有段MD5的代码看不懂，求助！ [Re:yingxue6666]
menzy 版主发贴: 754 积分: 113	于 2005-06-03 14:14 see see MD5.java (15.6k)

作者	Re:求助版主及各位高手！我有段MD5的代码看不懂，求助！ [Re:yingxue6666]
yingxue6666 发贴: 13 积分: 0	于 2005-06-04 10:55 谢谢，我先看看，说真的，MD5方面的资料我看了一些，但是具体的每条语句是什么意思，我不懂，为了作毕业设计，是现学的JAVA和MD5，就是怕答辩哪天老师问的详细，那样的话就不好办了

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