XXTEA的实现（javascript版本）

//对某个app进行逆向分析的时候，发现是xxtea算法，记录一下。密文可以选择是十六进制格式与base64编码格式

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 str2Hex(long2str(v, false));
}

function xxtea_decrypt(str, key) {
    if (str == "") {
        return "";
    }

    str=hex2str(str);
    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 str2Hex(input) { 
    var output = ""; 
    var chr1 = ""; 
    var i = 0;
    do { 
        chr1 = input.charCodeAt(i++).toString(16); 
	if(chr1.length==1)chr1="0"+chr1;
	output+=chr1;
    } while (i < input.length);
    return output; 
}

function hex2str(input) {
    var output="";
    var i=0;
    while(i> 2; 
        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4); 
        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6); 
        enc4 = chr3 & 63;
        if (isNaN(chr2)) { 
            enc3 = enc4 = 64; 
        } else if (isNaN(chr3)) { 
            enc4 = 64; 
        }
        output = output + 
           Base64._keyStr.charAt(enc1) + 
           Base64._keyStr.charAt(enc2) + 
           Base64._keyStr.charAt(enc3) + 
           Base64._keyStr.charAt(enc4); 
        chr1 = chr2 = chr3 = ""; 
        enc1 = enc2 = enc3 = enc4 = ""; 
    } while (i < input.length);
    return output; 
}

Base64.decode64 = function (input) { 
    var output = ""; 
    var chr1, chr2, chr3 = ""; 
    var enc1, enc2, enc3, enc4 = ""; 
    var i = 0;
    var base64test = /[^A-Za-z0-9\+\/\=\n]/g; 
    if (base64test.exec(input)) { 
        return "error";
    } 
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
    do { 
        enc1 = Base64._keyStr.indexOf(input.charAt(i++)); 
        enc2 = Base64._keyStr.indexOf(input.charAt(i++)); 
        enc3 = Base64._keyStr.indexOf(input.charAt(i++)); 
        enc4 = Base64._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; 
}