102 lines
2 KiB
JavaScript
102 lines
2 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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/** @preserve
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* Counter block mode compatible with Dr Brian Gladman fileenc.c
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* derived from CryptoJS.mode.CTR
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* Jan Hruby jhruby.web@gmail.com
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*/
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CryptoJS.mode.CTRGladman = (function () {
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var CTRGladman = CryptoJS.lib.BlockCipherMode.extend();
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function incWord(word)
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{
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if (((word >> 24) & 0xff) === 0xff) { //overflow
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var b1 = (word >> 16)&0xff;
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var b2 = (word >> 8)&0xff;
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var b3 = word & 0xff;
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if (b1 === 0xff) // overflow b1
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{
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b1 = 0;
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if (b2 === 0xff)
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{
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b2 = 0;
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if (b3 === 0xff)
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{
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b3 = 0;
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}
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else
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{
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++b3;
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}
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}
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else
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{
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++b2;
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}
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}
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else
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{
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++b1;
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}
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word = 0;
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word += (b1 << 16);
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word += (b2 << 8);
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word += b3;
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}
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else
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{
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word += (0x01 << 24);
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}
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return word;
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}
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function incCounter(counter)
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{
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if ((counter[0] = incWord(counter[0])) === 0)
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{
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// encr_data in fileenc.c from Dr Brian Gladman's counts only with DWORD j < 8
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counter[1] = incWord(counter[1]);
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}
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return counter;
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}
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var Encryptor = CTRGladman.Encryptor = CTRGladman.extend({
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processBlock: function (words, offset) {
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// Shortcuts
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var cipher = this._cipher
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var blockSize = cipher.blockSize;
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var iv = this._iv;
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var counter = this._counter;
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// Generate keystream
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if (iv) {
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counter = this._counter = iv.slice(0);
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// Remove IV for subsequent blocks
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this._iv = undefined;
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}
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incCounter(counter);
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var keystream = counter.slice(0);
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cipher.encryptBlock(keystream, 0);
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// Encrypt
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for (var i = 0; i < blockSize; i++) {
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words[offset + i] ^= keystream[i];
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}
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}
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});
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CTRGladman.Decryptor = Encryptor;
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return CTRGladman;
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}());
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