public class Md5 { // 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,且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[]; private long count[]; private byte 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[]; // 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 Md5() { state = new long[4]; count = new long[2]; buffer = new byte[64]; digest = new byte[16]; md5Init(); } // 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 al[], byte abyte0[], int i) { int j = 0; for(int k = 0; k < i; k += 4) { al[j] = b2iu(abyte0[k]) | b2iu(abyte0[k + 1]) << 8 | b2iu(abyte0[k + 2]) << 16 | b2iu(abyte0[k + 3]) << 24; j++; } } // 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 abyte0[], long al[], int i) { int j = 0; for(int k = 0; k < i; k += 4) { abyte0[k] = (byte)(int)(al[j] & 255L); abyte0[k + 1] = (byte)(int)(al[j] >>> 8 & 255L); abyte0[k + 2] = (byte)(int)(al[j] >>> 16 & 255L); abyte0[k + 3] = (byte)(int)(al[j] >>> 24 & 255L); j++; } } // 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 // 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 F(long l, long l1, long l2) { return l & l1 | ~l & l2; } private long FF(long l, long l1, long l2, long l3, long l4, long l5, long l6) { l += F(l1, l2, l3) + l4 + l6; l = (int)l << (int)l5 | (int)l >>> (int)(32L - l5); l += l1; return l; } private long G(long l, long l1, long l2) { return l & l2 | l1 & ~l2; } private long GG(long l, long l1, long l2, long l3, long l4, long l5, long l6) { l += G(l1, l2, l3) + l4 + l6; l = (int)l << (int)l5 | (int)l >>> (int)(32L - l5); l += l1; return l; } private long H(long l, long l1, long l2) { return l ^ l1 ^ l2; } private long HH(long l, long l1, long l2, long l3, long l4, long l5, long l6) { l += H(l1, l2, l3) + l4 + l6; l = (int)l << (int)l5 | (int)l >>> (int)(32L - l5); l += l1; return l; } private long I(long l, long l1, long l2) { return l1 ^ (l | ~l2); } private long II(long l, long l1, long l2, long l3, long l4, long l5, long l6) { l += I(l1, l2, l3) + l4 + l6; l = (int)l << (int)l5 | (int)l >>> (int)(32L - l5); l += l1; return l; } // b2iu是一个把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 byte0) { return (long)(byte0 >= 0 ? byte0 : byte0 & 0xff); } // 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 byte0) { char ac[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; char ac1[] = new char[2]; ac1[0] = ac[byte0 >>> 4 & 0xf]; ac1[1] = ac[byte0 & 0xf]; String s = new String(ac1); return s; } // 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 s) { md5Init(); md5Update(s.getBytes(), s.length()); md5Final(); digestHexStr = ""; for(int i = 0; i < 16; i++) digestHexStr += byteHEX(digest[i]); return digestHexStr; } // md5Final整理和填写输出结果 private void md5Final() { byte abyte0[] = new byte[8]; Encode(abyte0, count, 8); int i = (int)(count[0] >>> 3) & 0x3f; int j = i >= 56 ? 120 - i : 56 - i; md5Update(PADDING, j); md5Update(abyte0, 8); Encode(digest, state, 16); } // 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; state[0] = 0x67452301L; state[1] = 0xefcdab89L; state[2] = 0x98badcfeL; state[3] = 0x10325476L; } // md5Memcpy是一个内部使用的byte数组的块拷贝函数,从abyte1的j开始把k长度的 // 字节拷贝到abyte0的i位置开始 private void md5Memcpy(byte abyte0[], byte abyte1[], int i, int j, int k) { for(int l = 0; l < k; l++) abyte0[i + l] = abyte1[j + l]; } // md5Transform是MD5核心变换程序,有md5Update调用,abyte0是分块的原始字节 private void md5Transform(byte abyte0[]) { long l = state[0]; long l1 = state[1]; long l2 = state[2]; long l3 = state[3]; long al[] = new long[16]; Decode(al, abyte0, 64); l = FF(l, l1, l2, l3, al[0], 7L, 0xd76aa478L); l3 = FF(l3, l, l1, l2, al[1], 12L, 0xe8c7b756L); l2 = FF(l2, l3, l, l1, al[2], 17L, 0x242070dbL); l1 = FF(l1, l2, l3, l, al[3], 22L, 0xc1bdceeeL); l = FF(l, l1, l2, l3, al[4], 7L, 0xf57c0fafL); l3 = FF(l3, l, l1, l2, al[5], 12L, 0x4787c62aL); l2 = FF(l2, l3, l, l1, al[6], 17L, 0xa8304613L); l1 = FF(l1, l2, l3, l, al[7], 22L, 0xfd469501L); l = FF(l, l1, l2, l3, al[8], 7L, 0x698098d8L); l3 = FF(l3, l, l1, l2, al[9], 12L, 0x8b44f7afL); l2 = FF(l2, l3, l, l1, al[10], 17L, 0xffff5bb1L); l1 = FF(l1, l2, l3, l, al[11], 22L, 0x895cd7beL); l = FF(l, l1, l2, l3, al[12], 7L, 0x6b901122L); l3 = FF(l3, l, l1, l2, al[13], 12L, 0xfd987193L); l2 = FF(l2, l3, l, l1, al[14], 17L, 0xa679438eL); l1 = FF(l1, l2, l3, l, al[15], 22L, 0x49b40821L); l = GG(l, l1, l2, l3, al[1], 5L, 0xf61e2562L); l3 = GG(l3, l, l1, l2, al[6], 9L, 0xc040b340L); l2 = GG(l2, l3, l, l1, al[11], 14L, 0x265e5a51L); l1 = GG(l1, l2, l3, l, al[0], 20L, 0xe9b6c7aaL); l = GG(l, l1, l2, l3, al[5], 5L, 0xd62f105dL); l3 = GG(l3, l, l1, l2, al[10], 9L, 0x2441453L); l2 = GG(l2, l3, l, l1, al[15], 14L, 0xd8a1e681L); l1 = GG(l1, l2, l3, l, al[4], 20L, 0xe7d3fbc8L); l = GG(l, l1, l2, l3, al[9], 5L, 0x21e1cde6L); l3 = GG(l3, l, l1, l2, al[14], 9L, 0xc33707d6L); l2 = GG(l2, l3, l, l1, al[3], 14L, 0xf4d50d87L); l1 = GG(l1, l2, l3, l, al[8], 20L, 0x455a14edL); l = GG(l, l1, l2, l3, al[13], 5L, 0xa9e3e905L); l3 = GG(l3, l, l1, l2, al[2], 9L, 0xfcefa3f8L); l2 = GG(l2, l3, l, l1, al[7], 14L, 0x676f02d9L); l1 = GG(l1, l2, l3, l, al[12], 20L, 0x8d2a4c8aL); l = HH(l, l1, l2, l3, al[5], 4L, 0xfffa3942L); l3 = HH(l3, l, l1, l2, al[8], 11L, 0x8771f681L); l2 = HH(l2, l3, l, l1, al[11], 16L, 0x6d9d6122L); l1 = HH(l1, l2, l3, l, al[14], 23L, 0xfde5380cL); l = HH(l, l1, l2, l3, al[1], 4L, 0xa4beea44L); l3 = HH(l3, l, l1, l2, al[4], 11L, 0x4bdecfa9L); l2 = HH(l2, l3, l, l1, al[7], 16L, 0xf6bb4b60L); l1 = HH(l1, l2, l3, l, al[10], 23L, 0xbebfbc70L); l = HH(l, l1, l2, l3, al[13], 4L, 0x289b7ec6L); l3 = HH(l3, l, l1, l2, al[0], 11L, 0xeaa127faL); l2 = HH(l2, l3, l, l1, al[3], 16L, 0xd4ef3085L); l1 = HH(l1, l2, l3, l, al[6], 23L, 0x4881d05L); l = HH(l, l1, l2, l3, al[9], 4L, 0xd9d4d039L); l3 = HH(l3, l, l1, l2, al[12], 11L, 0xe6db99e5L); l2 = HH(l2, l3, l, l1, al[15], 16L, 0x1fa27cf8L); l1 = HH(l1, l2, l3, l, al[2], 23L, 0xc4ac5665L); l = II(l, l1, l2, l3, al[0], 6L, 0xf4292244L); l3 = II(l3, l, l1, l2, al[7], 10L, 0x432aff97L); l2 = II(l2, l3, l, l1, al[14], 15L, 0xab9423a7L); l1 = II(l1, l2, l3, l, al[5], 21L, 0xfc93a039L); l = II(l, l1, l2, l3, al[12], 6L, 0x655b59c3L); l3 = II(l3, l, l1, l2, al[3], 10L, 0x8f0ccc92L); l2 = II(l2, l3, l, l1, al[10], 15L, 0xffeff47dL); l1 = II(l1, l2, l3, l, al[1], 21L, 0x85845dd1L); l = II(l, l1, l2, l3, al[8], 6L, 0x6fa87e4fL); l3 = II(l3, l, l1, l2, al[15], 10L, 0xfe2ce6e0L); l2 = II(l2, l3, l, l1, al[6], 15L, 0xa3014314L); l1 = II(l1, l2, l3, l, al[13], 21L, 0x4e0811a1L); l = II(l, l1, l2, l3, al[4], 6L, 0xf7537e82L); l3 = II(l3, l, l1, l2, al[11], 10L, 0xbd3af235L); l2 = II(l2, l3, l, l1, al[2], 15L, 0x2ad7d2bbL); l1 = II(l1, l2, l3, l, al[9], 21L, 0xeb86d391L); state[0] += l; state[1] += l1; state[2] += l2; state[3] += l3; } // md5Update是MD5的主计算过程,abyte0是要变换的字节串,i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 abyte0[], int i) { byte abyte1[] = new byte[64]; int k = (int)(count[0] >>> 3) & 0x3f; if((count[0] += i << 3) < (long)(i << 3)) count[1]++; count[1] += i >>> 29; int l = 64 - k; int j; if(i >= l) { md5Memcpy(buffer, abyte0, k, 0, l); md5Transform(buffer); for(j = l; j + 63 < i; j += 64) { md5Memcpy(abyte1, abyte0, 0, j, 64); md5Transform(abyte1); } k = 0; } else { j = 0; } md5Memcpy(buffer, abyte0, k, j, i - j); } }
//使用MD5,测试类TestMain public class TestMain { public static void main(String[] args) { Md5 md5=new Md5(); String md5String=md5.getMD5ofStr("想要转换的字符串"); System.out.println(md5String); } }