xunfeiAI/static/crypto-js/mode-cfb.js

80 lines
2.1 KiB
JavaScript

;(function (root, factory, undef) {
if (typeof exports === "object") {
// CommonJS
module.exports = exports = factory(require("./core"), require("./cipher-core"));
}
else if (typeof define === "function" && define.amd) {
// AMD
define(["./core", "./cipher-core"], factory);
}
else {
// Global (browser)
factory(root.CryptoJS);
}
}(this, function (CryptoJS) {
/**
* 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) {
var keystream;
// Shortcut
var iv = this._iv;
// Generate keystream
if (iv) {
keystream = iv.slice(0);
// Remove IV for subsequent blocks
this._iv = undefined;
} else {
keystream = this._prevBlock;
}
cipher.encryptBlock(keystream, 0);
// Encrypt
for (var i = 0; i < blockSize; i++) {
words[offset + i] ^= keystream[i];
}
}
return CFB;
}());
return CryptoJS.mode.CFB;
}));