MD5算法在JavaScript中的实现

/* to convert strings to a list of ascii values */ 
var sAscii = " !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
var sAscii = sAscii + "[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~"; 

/* convert integer to hex string */ 
var sHex = "0123456789ABCDEF"; 
function hex(i) 
{ 
h = ""; 
for(j = 0; j <= 3; j++) 
{ 
h += sHex.charAt((i >> (j * 8 + 4)) & 0x0F) + 
sHex.charAt((i >> (j * 8)) & 0x0F); 
} 
return h; 
} 

/* add, handling overflows correctly */ 
function add(x, y) 
{ 
return ((x&0x7FFFFFFF) + (y&0x7FFFFFFF)) ^ (x&0x80000000) ^ (y&0x80000000); 
} 

/* MD5 rounds functions */ 
function R1(A, B, C, D, X, S, T) 
{ 
q = add(add(A, (B & C) | (~B & D)), add(X, T)); 
return add((q << S) | ((q >> (32 - S)) & (Math.pow(2, S) - 1)), B); 
} 

function R2(A, B, C, D, X, S, T) 
{ 
q = add(add(A, (B & D) | (C & ~D)), add(X, T)); 
return add((q << S) | ((q >> (32 - S)) & (Math.pow(2, S) - 1)), B); 
} 

function R3(A, B, C, D, X, S, T) 
{ 
q = add(add(A, B ^ C ^ D), add(X, T)); 
return add((q << S) | ((q >> (32 - S)) & (Math.pow(2, S) - 1)), B); 
} 

function R4(A, B, C, D, X, S, T) 
{ 
q = add(add(A, C ^ (B | ~D)), add(X, T)); 
return add((q << S) | ((q >> (32 - S)) & (Math.pow(2, S) - 1)), B); 
} 

/* main entry point */ 
function calcMD5(sInp) { 

/* Calculate length in machine words, including padding */ 
wLen = (((sInp.length + 8) >> 6) + 1) << 4; 
var X = new Array(wLen); 

/* Convert string to array of words */ 
j = 4; 
for (i = 0; (i * 4) < sInp.length; i++) 
{ 
X[i] = 0; 
for (j = 0; (j < 4) && ((j + i * 4) < sInp.length); j++) 
{ 
X[i] += (sAscii.indexOf(sInp.charAt((i * 4) + j)) + 32) << (j * 8); 
} 
} 

/* Append padding bits and length */ 
if (j == 4) 
{ 
X[i++] = 0x80; 
} 
else 
{ 
X[i - 1] += 0x80 << (j * 8); 
} 
for(; i < wLen; i++) { X[i] = 0; } 
X[wLen - 2] = sInp.length * 8; 

/* hard-coded initial values */ 
a = 0x67452301; 
b = 0xefcdab89; 
c = 0x98badcfe; 
d = 0x10325476; 

/* Process each 16-word block in turn */ 
for (i = 0; i < wLen; i += 16) { 
aO = a; 
bO = b; 
cO = c; 
dO = d; 

a = R1(a, b, c, d, X[i+ 0], 7 , 0xd76aa478); 
d = R1(d, a, b, c, X[i+ 1], 12, 0xe8c7b756); 
c = R1(c, d, a, b, X[i+ 2], 17, 0x242070db); 
b = R1(b, c, d, a, X[i+ 3], 22, 0xc1bdceee); 
a = R1(a, b, c, d, X[i+ 4], 7 , 0xf57c0faf); 
d = R1(d, a, b, c, X[i+ 5], 12, 0x4787c62a); 
c = R1(c, d, a, b, X[i+ 6], 17, 0xa8304613); 
b = R1(b, c, d, a, X[i+ 7], 22, 0xfd469501); 
a = R1(a, b, c, d, X[i+ 8], 7 , 0x698098d8); 
d = R1(d, a, b, c, X[i+ 9], 12, 0x8b44f7af); 
c = R1(c, d, a, b, X[i+10], 17, 0xffff5bb1); 
b = R1(b, c, d, a, X[i+11], 22, 0x895cd7be); 
a = R1(a, b, c, d, X[i+12], 7 , 0x6b901122); 
d = R1(d, a, b, c, X[i+13], 12, 0xfd987193); 
c = R1(c, d, a, b, X[i+14], 17, 0xa679438e); 
b = R1(b, c, d, a, X[i+15], 22, 0x49b40821); 

a = R2(a, b, c, d, X[i+ 1], 5 , 0xf61e2562); 
d = R2(d, a, b, c, X[i+ 6], 9 , 0xc040b340); 
c = R2(c, d, a, b, X[i+11], 14, 0x265e5a51); 
b = R2(b, c, d, a, X[i+ 0], 20, 0xe9b6c7aa); 
a = R2(a, b, c, d, X[i+ 5], 5 , 0xd62f105d); 
d = R2(d, a, b, c, X[i+10], 9 , 0x2441453); 
c = R2(c, d, a, b, X[i+15], 14, 0xd8a1e681); 
b = R2(b, c, d, a, X[i+ 4], 20, 0xe7d3fbc8); 
a = R2(a, b, c, d, X[i+ 9], 5 , 0x21e1cde6); 
d = R2(d, a, b, c, X[i+14], 9 , 0xc33707d6); 
c = R2(c, d, a, b, X[i+ 3], 14, 0xf4d50d87); 
b = R2(b, c, d, a, X[i+ 8], 20, 0x455a14ed); 
a = R2(a, b, c, d, X[i+13], 5 , 0xa9e3e905); 
d = R2(d, a, b, c, X[i+ 2], 9 , 0xfcefa3f8); 
c = R2(c, d, a, b, X[i+ 7], 14, 0x676f02d9); 
b = R2(b, c, d, a, X[i+12], 20, 0x8d2a4c8a); 

a = R3(a, b, c, d, X[i+ 5], 4 , 0xfffa3942); 
d = R3(d, a, b, c, X[i+ 8], 11, 0x8771f681); 
c = R3(c, d, a, b, X[i+11], 16, 0x6d9d6122); 
b = R3(b, c, d, a, X[i+14], 23, 0xfde5380c); 
a = R3(a, b, c, d, X[i+ 1], 4 , 0xa4beea44); 
d = R3(d, a, b, c, X[i+ 4], 11, 0x4bdecfa9); 
c = R3(c, d, a, b, X[i+ 7], 16, 0xf6bb4b60); 
b = R3(b, c, d, a, X[i+10], 23, 0xbebfbc70); 
a = R3(a, b, c, d, X[i+13], 4 , 0x289b7ec6); 
d = R3(d, a, b, c, X[i+ 0], 11, 0xeaa127fa); 
c = R3(c, d, a, b, X[i+ 3], 16, 0xd4ef3085); 
b = R3(b, c, d, a, X[i+ 6], 23, 0x4881d05); 
a = R3(a, b, c, d, X[i+ 9], 4 , 0xd9d4d039); 
d = R3(d, a, b, c, X[i+12], 11, 0xe6db99e5); 
c = R3(c, d, a, b, X[i+15], 16, 0x1fa27cf8); 
b = R3(b, c, d, a, X[i+ 2], 23, 0xc4ac5665); 

a = R4(a, b, c, d, X[i+ 0], 6 , 0xf4292244); 
d = R4(d, a, b, c, X[i+ 7], 10, 0x432aff97); 
c = R4(c, d, a, b, X[i+14], 15, 0xab9423a7); 
b = R4(b, c, d, a, X[i+ 5], 21, 0xfc93a039); 
a = R4(a, b, c, d, X[i+12], 6 , 0x655b59c3); 
d = R4(d, a, b, c, X[i+ 3], 10, 0x8f0ccc92); 
c = R4(c, d, a, b, X[i+10], 15, 0xffeff47d); 
b = R4(b, c, d, a, X[i+ 1], 21, 0x85845dd1); 
a = R4(a, b, c, d, X[i+ 8], 6 , 0x6fa87e4f); 
d = R4(d, a, b, c, X[i+15], 10, 0xfe2ce6e0); 
c = R4(c, d, a, b, X[i+ 6], 15, 0xa3014314); 
b = R4(b, c, d, a, X[i+13], 21, 0x4e0811a1); 
a = R4(a, b, c, d, X[i+ 4], 6 , 0xf7537e82); 
d = R4(d, a, b, c, X[i+11], 10, 0xbd3af235); 
c = R4(c, d, a, b, X[i+ 2], 15, 0x2ad7d2bb); 
b = R4(b, c, d, a, X[i+ 9], 21, 0xeb86d391); 

a = add(a, aO); 
b = add(b, bO); 
c = add(c, cO); 
d = add(d, dO); 
} 
return hex(a) + hex(b) + hex(c) + hex(d); 
}