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- /*
- CryptoJS v3.1.2
- code.google.com/p/crypto-js
- (c) 2009-2013 by Jeff Mott. All rights reserved.
- code.google.com/p/crypto-js/wiki/License
- */
- /**
- * Cipher Feedback block mode.
- */
- CryptoJS.mode.CFB = (function () {
- var CFB = CryptoJS.lib.BlockCipherMode.extend();
- CFB.Encryptor = CFB.extend({
- processBlock: function (words, offset) {
- // Shortcuts
- var cipher = this._cipher;
- var blockSize = cipher.blockSize;
- generateKeystreamAndEncrypt.call(this, words, offset, blockSize, cipher);
- // Remember this block to use with next block
- this._prevBlock = words.slice(offset, offset + blockSize);
- }
- });
- CFB.Decryptor = CFB.extend({
- processBlock: function (words, offset) {
- // Shortcuts
- var cipher = this._cipher;
- var blockSize = cipher.blockSize;
- // Remember this block to use with next block
- var thisBlock = words.slice(offset, offset + blockSize);
- generateKeystreamAndEncrypt.call(this, words, offset, blockSize, cipher);
- // This block becomes the previous block
- this._prevBlock = thisBlock;
- }
- });
- function generateKeystreamAndEncrypt(words, offset, blockSize, cipher) {
- // Shortcut
- var iv = this._iv;
- // Generate keystream
- if (iv) {
- var keystream = iv.slice(0);
- // Remove IV for subsequent blocks
- this._iv = undefined;
- } else {
- var keystream = this._prevBlock;
- }
- cipher.encryptBlock(keystream, 0);
- // Encrypt
- for (var i = 0; i < blockSize; i++) {
- words[offset + i] ^= keystream[i];
- }
- }
- return CFB;
- }());
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