base64和Xxtea的加密和解密

數據加密是web數據安全的一種方式，前幾天拿到一個base64+xxtea加密的數據，現在在這里整理一下使用的過程。首先當然是全網站找解密方法，但是最后的結果不是很理想，都不是自己想要的，這里只針對前端js的加密和解密

看代碼：

``` function long2str(v, w) { var vl = v.length; var sl = v[vl - 1] & 0xffffffff; for (var i = 0; i < vl; i++) { v[i] = String.fromCharCode(v[i] & 0xff, v[i] >>> 8 & 0xff, v[i] >>> 16 & 0xff, v[i] >>> 24 & 0xff); } if (w) { return v.join('').substring(0, sl); } else { return v.join(''); } }

function str2long(s, w) { var len = s.length; var v = []; for (var i = 0; i < len; i += 4) { v[i >> 2] = s.charCodeAt(i) | s.charCodeAt(i + 1) << 8 | s.charCodeAt(i + 2) << 16 | s.charCodeAt(i + 3) << 24; } if (w) { v[v.length] = len; } return v; }

function xxtea_encrypt(str, key) { if (str == "") { return ""; } var v = str2long(str, true); var k = str2long(key, false); var n = v.length - 1;

var z = v[n], y = v[0], delta = 0x9E3779B9;

var mx, e, q = Math.floor(6 + 52 / (n + 1)), sum = 0;

while (q-- > 0) {

sum = sum + delta & 0xffffffff;

e = sum >>> 2 & 3;

for (var p = 0; p < n; p++) {

y = v[p + 1];

mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);

z = v[p] = v[p] + mx & 0xffffffff;

}

y = v[0];

mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);

z = v[n] = v[n] + mx & 0xffffffff;

}

return long2str(v, false);

}

function xxtea_decrypt(str, key) { if (str == "") { return ""; } var v = str2long(str, false); var k = str2long(key, false); var n = v.length - 1;

var z = v[n - 1], y = v[0], delta = 0x9E3779B9;

var mx, e, q = Math.floor(6 + 52 / (n + 1)), sum = q * delta & 0xffffffff;

while (sum != 0) {

e = sum >>> 2 & 3;

for (var p = n; p > 0; p--) {

z = v[p - 1];

mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);

y = v[p] = v[p] - mx & 0xffffffff;

}

z = v[n];

mx = (z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z);

y = v[0] = v[0] - mx & 0xffffffff;

sum = sum - delta & 0xffffffff;

}

return long2str(v, true);

}

function utf16to8(str) { var out, i, len, c;

out = [];

len = str.length;

for(i = 0; i < len; i++) {

c = str.charCodeAt(i);

if ((c >= 0x0001) && (c <= 0x007F)) {

out[i] = str.charAt(i);

} else if (c > 0x07FF) {

out[i] = String.fromCharCode(0xE0 | ((c >> 12) & 0x0F),

0x80 | ((c >> 6) & 0x3F),

0x80 | ((c >> 0) & 0x3F));

} else {

out[i] = String.fromCharCode(0xC0 | ((c >> 6) & 0x1F),

0x80 | ((c >> 0) & 0x3F));

}

}

return out.join('');

}

function utf8to16(str) { var out, i, len, c; var char2, char3;

out = [];

len = str.length;

i = 0;

while(i < len) {

c = str.charCodeAt(i++);

switch(c >> 4)

{

case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:

// 0xxxxxxx

out[out.length] = str.charAt(i-1);

break;

case 12: case 13:

// 110x xxxx 10xx xxxx

char2 = str.charCodeAt(i++);

out[out.length] = String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));

break;

case 14:

// 1110 xxxx 10xx xxxx 10xx xxxx

char2 = str.charCodeAt(i++);

char3 = str.charCodeAt(i++);

out[out.length] = String.fromCharCode(((c & 0x0F) << 12) |

((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));

break;

}

}

return out.join('');

}

//base64解碼 function decode_base64(input) { var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

var output = "";

var chr1, chr2, chr3 = "";

var enc1, enc2, enc3, enc4 = "";

var i = 0;

// remove all characters that are not A-Z, a-z, 0-9, +, /, or =

var base64test = /[^A-Za-z0-9\+\/\=\n]/g;

if (base64test.exec(input)) {

}

input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

do {

enc1 = keyStr.indexOf(input.charAt(i++));

enc2 = keyStr.indexOf(input.charAt(i++));

enc3 = keyStr.indexOf(input.charAt(i++));

enc4 = keyStr.indexOf(input.charAt(i++));

chr1 = (enc1 << 2) | (enc2 >> 4);

chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);

chr3 = ((enc3 & 3) << 6) | enc4;

output = output + String.fromCharCode(chr1);

if (enc3 != 64) {

output = output + String.fromCharCode(chr2);

}

if (enc4 != 64) {

output = output + String.fromCharCode(chr3);

}

chr1 = chr2 = chr3 = "";

enc1 = enc2 = enc3 = enc4 = "";

} while (i < input.length);

return output;

}

然后就是使用：

```

xxtea解密函數的key參數，是數據加密的關鍵字，這個得著后端的程序員給你提供

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