TEA 加密算法

function encrypt(val, key)

{

// 128 bits (16 chars) of string 'key' are used to encrypt string 'val'; function

// returns encrypted version of 'val'.

var v = new Array(2), k = new Array(4), s = "", i;

val = escape(val);  // use escape() so only have single-byte chars to encode

k[0] = Str4ToLong(key.substr(0,4));

k[1] = Str4ToLong(key.substr(4,4)
a66c
);

k[2] = Str4ToLong(key.substr(8,4));

k[3] = Str4ToLong(key.substr(12,4));

for (i=0; i<val.length; i+=8) {  // encode val into s in 64-bit (8 char) blocks

v[0] = Str4ToLong(val.substr(i,4));

v[1] = Str4ToLong(val.substr(i+4,4));

code(v, k);

s += LongToStr4(v[0]) + LongToStr4(v[1]);

}

//  return(s)       // deleted NVS  2005.04.27

return(escape(s)) // corrected NVS 2005.04.27

// note: if val or key are passed as string objects, rather than strings, this

// function will throw an 'Object does not support this property or method' error

}

function decrypt(val, key)

{

var v = new Array(2), k = new Array(4), s = "", i;

k[0] = Str4ToLong(key.substr(0,4));

k[1] = Str4ToLong(key.substr(4,4));

k[2] = Str4ToLong(key.substr(8,4));

k[3] = Str4ToLong(key.substr(12,4));

val = unescape(val); // corrected NVS 2005.04.27

for (i=0; i<val.length; i+=8) {  // decode val into s in 64-bit (8 char) blocks

v[0] = Str4ToLong(val.substr(i,4));

v[1] = Str4ToLong(val.substr(i+4,4));

decode(v, k);

s += LongToStr4(v[0]) + LongToStr4(v[1]);

}

if (s.indexOf("/x00") != -1) {

// strip trailing null chars resulting from filling 4-char blocks

s = s.substr(0, s.indexOf("/x00"));

}

return(unescape(s));

}

function code(v, k)

{

// Extended TEA: this is the 1997 revised version of Needham & Wheeler''s algorithm

// params: v[2] 64-bit value block; k[4] 128-bit key

var y = v[0], z = v[1];

var delta = 0x9E3779B9, limit = delta*32, sum = 0;

while (sum != limit) {

y += (z<<4 ^ z>>>5)+z ^ sum+k[sum & 3];

sum += delta;

z += (y<<4 ^ y>>>5)+y ^ sum+k[sum>>>11 & 3];

// note: unsigned right-shift '>>>' is used in place of original '>>', due to lack

// of 'unsigned' type declaration in JavaScript (thanks to Karsten Kraus for this)

}

v[0] = y; v[1] = z;

}

function decode(v, k)

{

var y = v[0], z = v[1];

var delta = 0x9E3779B9, sum = delta*32;

while (sum != 0) {

z -= (y<<4 ^ y>>>5)+y ^ sum+k[sum>>>11 & 3];

sum -= delta;

y -= (z<<4 ^ z>>>5)+z ^ sum+k[sum & 3];

}

v[0] = y; v[1] = z;

}

function Str4ToLong(s)  // convert 4 chars of s to a numeric long

{

var v = s.charCodeAt(0) +

(s.charCodeAt(1)<<8) +

(s.charCodeAt(2)<<16) +

(s.charCodeAt(3)<<24);

return(isNaN(v) ? 0 : v);

}

function LongToStr4(v)  // convert a numeric long to 4 char string

{

var s = String.fromCharCode(v & 0xFF, v>>8 & 0xFF, v>>16 & 0xFF, v>>24 & 0xFF);

return(s);

}