65 lines
1.8 KiB
JavaScript
65 lines
1.8 KiB
JavaScript
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/*
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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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/**
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* Cipher Feedback block mode.
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*/
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CryptoJS.mode.CFB = (function () {
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var CFB = CryptoJS.lib.BlockCipherMode.extend();
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CFB.Encryptor = CFB.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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generateKeystreamAndEncrypt.call(this, words, offset, blockSize, cipher);
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// Remember this block to use with next block
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this._prevBlock = words.slice(offset, offset + blockSize);
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}
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});
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CFB.Decryptor = CFB.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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// Remember this block to use with next block
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var thisBlock = words.slice(offset, offset + blockSize);
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generateKeystreamAndEncrypt.call(this, words, offset, blockSize, cipher);
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// This block becomes the previous block
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this._prevBlock = thisBlock;
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}
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});
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function generateKeystreamAndEncrypt(words, offset, blockSize, cipher) {
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// Shortcut
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var iv = this._iv;
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// Generate keystream
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if (iv) {
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var keystream = iv.slice(0);
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// Remove IV for subsequent blocks
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this._iv = undefined;
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} else {
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var keystream = this._prevBlock;
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}
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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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return CFB;
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}());
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