45 lines
1.2 KiB
JavaScript
45 lines
1.2 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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/**
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* Counter block mode.
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*/
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CryptoJS.mode.CTR = (function () {
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var CTR = CryptoJS.lib.BlockCipherMode.extend();
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var Encryptor = CTR.Encryptor = CTR.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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var keystream = counter.slice(0);
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cipher.encryptBlock(keystream, 0);
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// Increment counter
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counter[blockSize - 1] = (counter[blockSize - 1] + 1) | 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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CTR.Decryptor = Encryptor;
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return CTR;
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}());
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