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niandeng
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* Licensed under a Creative Creative Commons Attribution 3.0 Unported License */
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/* without any warranty express or implied */
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/* http://creativecommons.org/licenses/by/3.0/ */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* Block TEA (xxtea) Tiny Encryption Algorithm implementation in ActionScript */
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/* (c) Wowza Media Systems, Inc 2010: www.wowzamedia.com */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* Block TEA (xxtea) Tiny Encryption Algorithm implementation in JavaScript */
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/* (c) Chris Veness 2002-2010: www.movable-type.co.uk/tea-block.html */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* Algorithm: David Wheeler & Roger Needham, Cambridge University Computer Lab */
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/* http://www.cl.cam.ac.uk/ftp/papers/djw-rmn/djw-rmn-tea.html (1994) */
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/* http://www.cl.cam.ac.uk/ftp/users/djw3/xtea.ps (1997) */
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/* http://www.cl.cam.ac.uk/ftp/users/djw3/xxtea.ps (1998) */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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package ckaction.act {
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public class TEA {
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/*
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* encrypt text using Corrected Block TEA (xxtea) algorithm
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*
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* @param {string} plaintext String to be encrypted (multi-byte safe)
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* @param {string} password Password to be used for encryption (1st 16 chars)
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* @returns {string} encrypted text
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*/
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public static function encrypt(plaintext:String, password:String):String {
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if (plaintext.length == 0) return ""; // nothing to encrypt
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// convert string to array of longs after converting any multi-byte chars to UTF-8
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var v:Array = charsToLongs(strToChars(plaintext));
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if (v.length <= 1) v[1] = 0; // algorithm doesn't work for n<2 so fudge by adding a null
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// simply convert first 16 chars of password as key
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var k:Array = charsToLongs(strToChars(password.substr(0, 16)));
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var n:Number = v.length;
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// ---- <TEA coding> ----
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var z:Number = v[n-1], y:Number = v[0], delta:Number = 0x9E3779B9;
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var mx:Number, e:Number, q:Number = Math.floor(6 + 52/n), sum:Number = 0;
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while (q-- > 0) { // 6 + 52/n operations gives between 6 & 32 mixes on each word
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sum += delta;
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e = sum>>>2 & 3;
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for (var p:Number = 0; p < n; p++) {
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y = v[(p+1)%n];
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mx = (z>>>5 ^ y<<2) + (y>>>3 ^ z<<4) ^ (sum^y) + (k[p&3 ^ e] ^ z);
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z = v[p] += mx;
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}
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}
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// ---- </TEA> ----
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var ciphertext:Array = longsToChars(v);
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return charsToHex(ciphertext);
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}
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/*
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* decrypt text using Corrected Block TEA (xxtea) algorithm
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*
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* @param {string} ciphertext String to be decrypted
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* @param {string} password Password to be used for decryption (1st 16 chars)
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* @returns {string} decrypted text
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*/
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public static function decrypt(ciphertext:String, password:String):String {
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if (ciphertext.length == 0) return "";
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var v:Array = charsToLongs(hexToChars(ciphertext));
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var k:Array = charsToLongs(strToChars(password.substr(0, 16)));
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var n:Number = v.length;
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// ---- <TEA decoding> ----
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var z:Number = v[n-1], y:Number = v[0], delta:Number = 0x9E3779B9;
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var mx:Number, e:Number, q:Number = Math.floor(6 + 52/n), sum:Number = q*delta;
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while (sum != 0) {
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e = sum>>>2 & 3;
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for (var p:Number = n-1; p >= 0; p--) {
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z = v[p>0 ? p-1 : n-1];
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mx = (z>>>5 ^ y<<2) + (y>>>3 ^ z<<4) ^ (sum^y) + (k[p&3 ^ e] ^ z);
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y = v[p] -= mx;
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}
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sum -= delta;
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}
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// ---- </TEA> ----
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var plaintext:Array = longsToChars(v);
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return charsToStr(plaintext);
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}
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/**
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* Private methods.
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*/
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private static function charsToLongs(chars:Array):Array {
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var temp:Array = new Array(Math.ceil(chars.length/4));
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for (var i:Number = 0; i<temp.length; i++) {
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temp[i] = chars[i*4] + (chars[i*4+1]<<8) + (chars[i*4+2]<<16) + (chars[i*4+3]<<24);
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}
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return temp;
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}
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private static function longsToChars(longs:Array):Array {
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var codes:Array = new Array();
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for (var i:Number = 0; i<longs.length; i++) {
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codes.push(longs[i] & 0xFF, longs[i]>>>8 & 0xFF, longs[i]>>>16 & 0xFF, longs[i]>>>24 & 0xFF);
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}
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return codes;
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}
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private static function longToChars(longs:Number):Array {
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var codes:Array = new Array();
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codes.push(longs & 0xFF, longs>>>8 & 0xFF, longs>>>16 & 0xFF, longs>>>24 & 0xFF);
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return codes;
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}
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private static function charsToHex(chars:Array):String {
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var result:String = new String("");
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var hexes:Array = new Array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f");
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for (var i:Number = 0; i<chars.length; i++) {
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result += hexes[chars[i] >> 4] + hexes[chars[i] & 0xf];
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}
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return result;
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}
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private static function hexToChars(hex:String):Array {
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var codes:Array = new Array();
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for (var i:Number = (hex.substr(0, 2) == "0x") ? 2 : 0; i<hex.length; i+=2) {
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codes.push(parseInt(hex.substr(i, 2), 16));
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}
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return codes;
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}
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private static function charsToStr(chars:Array):String {
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var result:String = new String("");
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for (var i:Number = 0; i<chars.length; i++) {
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result += String.fromCharCode(chars[i]);
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}
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return result;
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}
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private static function strToChars(str:String):Array {
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var codes:Array = new Array();
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for (var i:Number = 0; i<str.length; i++) {
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codes.push(str.charCodeAt(i));
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}
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return codes;
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}
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}
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}
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