126 lines
3.1 KiB
JavaScript
126 lines
3.1 KiB
JavaScript
/*
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CryptoJS v3.1.2
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code.google.com/p/crypto-js
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(c) 2009-2013 by Jeff Mott. All rights reserved.
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code.google.com/p/crypto-js/wiki/License
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*/
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(function () {
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// Shortcuts
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var C = CryptoJS;
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var C_lib = C.lib;
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var StreamCipher = C_lib.StreamCipher;
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var C_algo = C.algo;
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/**
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* RC4 stream cipher algorithm.
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*/
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var RC4 = C_algo.RC4 = StreamCipher.extend({
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_doReset: function () {
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// Shortcuts
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var key = this._key;
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var keyWords = key.words;
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var keySigBytes = key.sigBytes;
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// Init sbox
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var S = this._S = [];
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for (var i = 0; i < 256; i++) {
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S[i] = i;
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}
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// Key setup
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for (var i = 0, j = 0; i < 256; i++) {
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var keyByteIndex = i % keySigBytes;
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var keyByte = (keyWords[keyByteIndex >>> 2] >>> (24 - (keyByteIndex % 4) * 8)) & 0xff;
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j = (j + S[i] + keyByte) % 256;
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// Swap
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var t = S[i];
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S[i] = S[j];
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S[j] = t;
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}
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// Counters
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this._i = this._j = 0;
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},
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_doProcessBlock: function (M, offset) {
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M[offset] ^= generateKeystreamWord.call(this);
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},
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keySize: 256/32,
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ivSize: 0
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});
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function generateKeystreamWord() {
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// Shortcuts
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var S = this._S;
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var i = this._i;
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var j = this._j;
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// Generate keystream word
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var keystreamWord = 0;
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for (var n = 0; n < 4; n++) {
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i = (i + 1) % 256;
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j = (j + S[i]) % 256;
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// Swap
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var t = S[i];
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S[i] = S[j];
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S[j] = t;
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keystreamWord |= S[(S[i] + S[j]) % 256] << (24 - n * 8);
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}
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// Update counters
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this._i = i;
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this._j = j;
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return keystreamWord;
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}
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/**
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* Shortcut functions to the cipher's object interface.
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*
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* @example
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*
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* var ciphertext = CryptoJS.RC4.encrypt(message, key, cfg);
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* var plaintext = CryptoJS.RC4.decrypt(ciphertext, key, cfg);
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*/
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C.RC4 = StreamCipher._createHelper(RC4);
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/**
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* Modified RC4 stream cipher algorithm.
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*/
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var RC4Drop = C_algo.RC4Drop = RC4.extend({
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/**
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* Configuration options.
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*
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* @property {number} drop The number of keystream words to drop. Default 192
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*/
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cfg: RC4.cfg.extend({
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drop: 192
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}),
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_doReset: function () {
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RC4._doReset.call(this);
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// Drop
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for (var i = this.cfg.drop; i > 0; i--) {
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generateKeystreamWord.call(this);
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}
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}
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});
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/**
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* Shortcut functions to the cipher's object interface.
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*
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* @example
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*
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* var ciphertext = CryptoJS.RC4Drop.encrypt(message, key, cfg);
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* var plaintext = CryptoJS.RC4Drop.decrypt(ciphertext, key, cfg);
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*/
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C.RC4Drop = StreamCipher._createHelper(RC4Drop);
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}());
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