江苏龙网

  1. 主页 > 生活百科 > >

MD5算法全解析( 二 )

MD5


  • FF(a,b,c,d,Mi,s,Kj) ：表示b+((a+F(b,c,d)+Mi+Kj)<<<s)
  • GG(a,b,c,d,Mi,s,Kj) ：表示b+((a+G(b,c,d)+Mi+Kj)<<<s)
  • HH(a,b,c,d,Mi,s,Kj) ：表示b+((a+H(b,c,d)+Mi+Kj)<<<s)
  • II(a,b,c,d,Mi,s,Kj) ：表示b+((a+I(b,c,d)+Mi+Kj)<<<s)
四、算法实现
public class MD5 { //16进制数字 private static final String[] hexes = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"}; //标准的幻数 private static final long A = 0X67452301; private static final long B = 0XEFCDAB89; private static final long C = 0X98BADCFE; private static final long D = 0X10325476; //位移量s,行为轮 ， 总共有4轮 ， 列为每轮中的一次循环 ， 总共16次 //下面这些S11-S44实际上是一个4*4的矩阵 ， 在四轮循环运算中用到 private static final int S11 = 7; private static final int S12 = 12; private static final int S13 = 17; private static final int S14 = 22; private static final int S21 = 5; private static final int S22 = 9; private static final int S23 = 14; private static final int S24 = 20; private static final int S31 = 4; private static final int S32 = 11; private static final int S33 = 16; private static final int S34 = 23; private static final int S41 = 6; private static final int S42 = 10; private static final int S43 = 15; private static final int S44 = 21; //结果,共4*32=128位 ， 初始值为幻数 private long[] result = {A, B, C, D}; /** * 计算字符串数据的MD5值并返回 * * @param src 数据 * @return 返回数据的MD5值 */ public String digest(String src) { byte[] inputBytes = src.getBytes(); int byteLen = inputBytes.length;//长度（字节） //完整分组的个数 int groupCount = byteLen / 64;//每组512位（64字节） long[] group;//每个小组(64字节)再细分后的16个小组(4字节) //处理每一个完整分组 for (int step = 0; step < groupCount; step++) { group = divGroup(inputBytes, step * 64); trans(group);//处理分组 ， 核心算法 } //处理完整分组后的尾巴 int rest = byteLen % 64;//512位分组后的余数 byte[] tempBytes = new byte[64]; //56个字节即488 if (rest <= 56) { for (int i = 0; i < rest; i++) tempBytes[i] = inputBytes[byteLen - rest + i]; //不断填充 if (rest < 56) { //最高位填充1 tempBytes[rest] = (byte) (1 << 7); //其余位填充0 for (int i = 1; i < 56 - rest; i++) tempBytes[rest + i] = 0; } long len = (long) (byteLen << 3); for (int i = 0; i < 8; i++) { tempBytes[56 + i] = (byte) (len & 0xFFL); len = len >> 8; } group = divGroup(tempBytes, 0); trans(group);//处理分组 } else { for (int i = 0; i < rest; i++) tempBytes[i] = inputBytes[byteLen - rest + i]; tempBytes[rest] = (byte) (1 << 7); for (int i = rest + 1; i < 64; i++) tempBytes[i] = 0; group = divGroup(tempBytes, 0); trans(group);//处理分组 for (int i = 0; i < 56; i++) tempBytes[i] = 0; long len = (long) (byteLen << 3); for (int i = 0; i < 8; i++) { tempBytes[56 + i] = (byte) (len & 0xFFL); len = len >> 8; } group = divGroup(tempBytes, 0); trans(group);//处理分组 } //将Hash值转换成十六进制的字符串 String resStr = ""; long temp; for (int i = 0; i < 4; i++) { for (int j = 0; j < 4; j++) { temp = result[i] & 0x0FL; String a = hexes[(int) (temp)]; result[i] = result[i] >> 4; temp = result[i] & 0x0FL; resStr += hexes[(int) (temp)] + a; result[i] = result[i] >> 4; } } return resStr; } /** * 从inputBytes的index开始取512位 ， 作为新的分组 * 将每一个512位的分组再细分成16个小组 ， 每个小组32位（8个字节） * * @param inputBytes * @param index * @return M */ private static long[] divGroup(byte[] inputBytes, int index) { long[] temp = new long[16]; for (int i = 0; i < 16; i++) { temp[i] = b2iu(inputBytes[4 * i + index]) | (b2iu(inputBytes[4 * i + 1 + index])) << 8 | (b2iu(inputBytes[4 * i + 2 + index])) << 16 | (b2iu(inputBytes[4 * i + 3 + index])) << 24; } return temp; } /** * 这时不存在符号位（符号位存储不再是代表正负） ， 所以需要处理一下 */ private static long b2iu(byte b) { return b < 0 ? b & 0x7F + 128 : b; } /** * 主要的操作 ， 四轮循环 * @param groups--每一个分组512位（64字节） */ private void trans(long[] groups) { long a = result[0], b = result[1], c = result[2], d = result[3]; /*第一轮*/ a = FF(a, b, c, d, groups[0], S11, 0xd76aa478L); /* 1 */ d = FF(d, a, b, c, groups[1], S12, 0xe8c7b756L); /* 2 */ c = FF(c, d, a, b, groups[2], S13, 0x242070dbL); /* 3 */ b = FF(b, c, d, a, groups[3], S14, 0xc1bdceeeL); /* 4 */ a = FF(a, b, c, d, groups[4], S11, 0xf57c0fafL); /* 5 */ d = FF(d, a, b, c, groups[5], S12, 0x4787c62aL); /* 6 */ c = FF(c, d, a, b, groups[6], S13, 0xa8304613L); /* 7 */ b = FF(b, c, d, a, groups[7], S14, 0xfd469501L); /* 8 */ a = FF(a, b, c, d, groups[8], S11, 0x698098d8L); /* 9 */ d = FF(d, a, b, c, groups[9], S12, 0x8b44f7afL); /* 10 */ c = FF(c, d, a, b, groups[10], S13, 0xffff5bb1L); /* 11 */ b = FF(b, c, d, a, groups[11], S14, 0x895cd7beL); /* 12 */ a = FF(a, b, c, d, groups[12], S11, 0x6b901122L); /* 13 */ d = FF(d, a, b, c, groups[13], S12, 0xfd987193L); /* 14 */ c = FF(c, d, a, b, groups[14], S13, 0xa679438eL); /* 15 */ b = FF(b, c, d, a, groups[15], S14, 0x49b40821L); /* 16 */ /*第二轮*/ a = GG(a, b, c, d, groups[1], S21, 0xf61e2562L); /* 17 */ d = GG(d, a, b, c, groups[6], S22, 0xc040b340L); /* 18 */ c = GG(c, d, a, b, groups[11], S23, 0x265e5a51L); /* 19 */ b = GG(b, c, d, a, groups[0], S24, 0xe9b6c7aaL); /* 20 */ a = GG(a, b, c, d, groups[5], S21, 0xd62f105dL); /* 21 */ d = GG(d, a, b, c, groups[10], S22, 0x2441453L); /* 22 */ c = GG(c, d, a, b, groups[15], S23, 0xd8a1e681L); /* 23 */ b = GG(b, c, d, a, groups[4], S24, 0xe7d3fbc8L); /* 24 */ a = GG(a, b, c, d, groups[9], S21, 0x21e1cde6L); /* 25 */ d = GG(d, a, b, c, groups[14], S22, 0xc33707d6L); /* 26 */ c = GG(c, d, a, b, groups[3], S23, 0xf4d50d87L); /* 27 */ b = GG(b, c, d, a, groups[8], S24, 0x455a14edL); /* 28 */ a = GG(a, b, c, d, groups[13], S21, 0xa9e3e905L); /* 29 */ d = GG(d, a, b, c, groups[2], S22, 0xfcefa3f8L); /* 30 */ c = GG(c, d, a, b, groups[7], S23, 0x676f02d9L); /* 31 */ b = GG(b, c, d, a, groups[12], S24, 0x8d2a4c8aL); /* 32 */ /*第三轮*/ a = HH(a, b, c, d, groups[5], S31, 0xfffa3942L); /* 33 */ d = HH(d, a, b, c, groups[8], S32, 0x8771f681L); /* 34 */ c = HH(c, d, a, b, groups[11], S33, 0x6d9d6122L); /* 35 */ b = HH(b, c, d, a, groups[14], S34, 0xfde5380cL); /* 36 */ a = HH(a, b, c, d, groups[1], S31, 0xa4beea44L); /* 37 */ d = HH(d, a, b, c, groups[4], S32, 0x4bdecfa9L); /* 38 */ c = HH(c, d, a, b, groups[7], S33, 0xf6bb4b60L); /* 39 */ b = HH(b, c, d, a, groups[10], S34, 0xbebfbc70L); /* 40 */ a = HH(a, b, c, d, groups[13], S31, 0x289b7ec6L); /* 41 */ d = HH(d, a, b, c, groups[0], S32, 0xeaa127faL); /* 42 */ c = HH(c, d, a, b, groups[3], S33, 0xd4ef3085L); /* 43 */ b = HH(b, c, d, a, groups[6], S34, 0x4881d05L); /* 44 */ a = HH(a, b, c, d, groups[9], S31, 0xd9d4d039L); /* 45 */ d = HH(d, a, b, c, groups[12], S32, 0xe6db99e5L); /* 46 */ c = HH(c, d, a, b, groups[15], S33, 0x1fa27cf8L); /* 47 */ b = HH(b, c, d, a, groups[2], S34, 0xc4ac5665L); /* 48 */ /*第四轮*/ a = II(a, b, c, d, groups[0], S41, 0xf4292244L); /* 49 */ d = II(d, a, b, c, groups[7], S42, 0x432aff97L); /* 50 */ c = II(c, d, a, b, groups[14], S43, 0xab9423a7L); /* 51 */ b = II(b, c, d, a, groups[5], S44, 0xfc93a039L); /* 52 */ a = II(a, b, c, d, groups[12], S41, 0x655b59c3L); /* 53 */ d = II(d, a, b, c, groups[3], S42, 0x8f0ccc92L); /* 54 */ c = II(c, d, a, b, groups[10], S43, 0xffeff47dL); /* 55 */ b = II(b, c, d, a, groups[1], S44, 0x85845dd1L); /* 56 */ a = II(a, b, c, d, groups[8], S41, 0x6fa87e4fL); /* 57 */ d = II(d, a, b, c, groups[15], S42, 0xfe2ce6e0L); /* 58 */ c = II(c, d, a, b, groups[6], S43, 0xa3014314L); /* 59 */ b = II(b, c, d, a, groups[13], S44, 0x4e0811a1L); /* 60 */ a = II(a, b, c, d, groups[4], S41, 0xf7537e82L); /* 61 */ d = II(d, a, b, c, groups[11], S42, 0xbd3af235L); /* 62 */ c = II(c, d, a, b, groups[2], S43, 0x2ad7d2bbL); /* 63 */ b = II(b, c, d, a, groups[9], S44, 0xeb86d391L); /* 64 */ /*加入到之前计算的结果当中*/ result[0] += a; result[1] += b; result[2] += c; result[3] += d; result[0] = result[0] & 0xFFFFFFFFL; result[1] = result[1] & 0xFFFFFFFFL; result[2] = result[2] & 0xFFFFFFFFL; result[3] = result[3] & 0xFFFFFFFFL; } /** * 线性函数 */ 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)); } private long FF(long a, long b, long c, long d, long M, long s, long K) { a += (F(b, c, d) & 0xFFFFFFFFL) + M + K; a = ((a & 0xFFFFFFFFL) << s) | ((a & 0xFFFFFFFFL) >>> (32 - s)); a += b; return (a & 0xFFFFFFFFL); } private long GG(long a, long b, long c, long d, long M, long s, long K) { a += (G(b, c, d) & 0xFFFFFFFFL) + M + K; a = ((a & 0xFFFFFFFFL) << s) | ((a & 0xFFFFFFFFL) >>> (32 - s)); a += b; return (a & 0xFFFFFFFFL); } private long HH(long a, long b, long c, long d, long M, long s, long K) { a += (H(b, c, d) & 0xFFFFFFFFL) + M + K; a = ((a & 0xFFFFFFFFL) << s) | ((a & 0xFFFFFFFFL) >>> (32 - s)); a += b; return (a & 0xFFFFFFFFL); } private long II(long a, long b, long c, long d, long M, long s, long K) { a += (I(b, c, d) & 0xFFFFFFFFL) + M + K; a = ((a & 0xFFFFFFFFL) << s) | ((a & 0xFFFFFFFFL) >>> (32 - s)); a += b; return (a & 0xFFFFFFFFL); }}


推荐阅读


上一篇：3分钟快速了解TypeScript

下一篇：面向企业网络的九大带宽监控工具详解