javascript-api/XXTEA.js at master · Sofia2/javascript-api · GitHub

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/**
 * XXTEA encryption arithmetic library.
 *
 * useage: var xxtea = XXTEA.encrypt("to_be_encode", "key");
 *
 * @package js.crypto
 * @Copyright (C) 2006-2007 Ma Bingyao <andot@ujn.edu.cn>
 * @author: DSONet (dsonet@msn.com)
 * @version $Id$
 */
// private static member delta
var delta = 0x9E3779B9;

// private static method longArrayToString
function longArrayToString(data, includeLength) {
        var length = data.length
                , n = (length - 1) << 2;
        if (includeLength) {
                var m = data[length - 1];
                if ((m < n - 3) || (m > n)) return null;
                n = m;
        }
        for (var i = 0; i < length; ++i) {
                data[i] = String.fromCharCode(
                        data[i] & 0xff,
                        data[i] >>> 8 & 0xff,
                        data[i] >>> 16 & 0xff,
                        data[i] >>> 24 & 0xff
                );
        }
        if (includeLength) {
                return data.join("").substring(0, n);
        }
        else {
                return data.join("");
        }
}

// private static method stringToLongArray
function stringToLongArray(string, includeLength) {
        var length = string.length;
        var result = [];
        for (var i = 0; i < length; i += 4) {
                result[i >> 2] = string.charCodeAt(i) |
                        string.charCodeAt(i + 1) << 8     |
                        string.charCodeAt(i + 2) << 16    |
                        string.charCodeAt(i + 3) << 24;
        }
        if (includeLength) {
                result[result.length] = length;
        }
        return result;
}

function toByteArray(data, includeLength) {
            var n = data.length << 2;
            if (includeLength) {
                    var m = data[data.length - 1];
                    if (m > n) {
                            return null;
                    } else {
                            n = m;
                    }

            }

			var result = [];

            for (i = 0; i < n; i++) {
                    result[i] = ((data[i >>> 2] >>> ((i & 3) << 3)) & 0xff);
            }
            return result;
    }


// static class XXTEA
var XXTEA = {
        // public static method encrypt
        encrypt : function(string, key) {
                if (string == "") {
                        return "";
                }
                var v = stringToLongArray(string, true)
                        , k = stringToLongArray(key, false)
                        , n = v.length - 1
                        , z = v[n]
                        , y = v[0]
                        , mx, e, p
                        , q = Math.floor(6 + 52 / (n + 1))
                        , sum = 0;

                if (k.length < 4) {
                        k.length = 4;
                }

                while (0 <= --q) {
                        sum = sum + delta & 0xffffffff;
                        e = sum >> 2 & 3;
                        for (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 longArrayToString(v, false);

        },

        // public static method decrypt
        decrypt : function(string, key) {
                if (string == "") {
                        return "";
                }
                var v = stringToLongArray(string, false);
                var k = stringToLongArray(key, false);
                if (k.length < 4) {
                        k.length = 4;
                }
                var n = v.length - 1;

                var z = v[n - 1], y = v[0];
                var mx, e, p, q = Math.floor(6 + 52 / (n + 1)), sum = q * delta & 0xffffffff;
                while (sum != 0) {
                        e = sum >> 2 & 3;
                        for (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 longArrayToString(v, true);
        }
}