md5.java

md5 类实现了RSA Data Security, Inc.在提交给IETF 的RFC1321中的MD5 message-digest 算法。

/************************************************ 
MD5 算法的Java Bean 
*************************************************/ 

import java.lang.reflect.*; 

/************************************************* 
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 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，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); 
} 
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 MD5() { 
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 & 0xffL); 
output[j + 1] = (byte)((input >>> 8) & 0xffL); 
output[j + 2] = (byte)((input >>> 16) & 0xffL); 
output[j + 3] = (byte)((input >>> 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 = 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; 
} 
}