first

node_modules/crypto-es/lib/rc4.js

@@ -0,0 +1,119 @@
+import {
+  StreamCipher,
+} from './cipher-core.js';
+
+function generateKeystreamWord() {
+  // Shortcuts
+  const S = this._S;
+  let i = this._i;
+  let j = this._j;
+
+  // Generate keystream word
+  let keystreamWord = 0;
+  for (let n = 0; n < 4; n += 1) {
+    i = (i + 1) % 256;
+    j = (j + S[i]) % 256;
+
+    // Swap
+    const t = S[i];
+    S[i] = S[j];
+    S[j] = t;
+
+    keystreamWord |= S[(S[i] + S[j]) % 256] << (24 - n * 8);
+  }
+
+  // Update counters
+  this._i = i;
+  this._j = j;
+
+  return keystreamWord;
+}
+
+/**
+ * RC4 stream cipher algorithm.
+ */
+export class RC4Algo extends StreamCipher {
+  _doReset() {
+    // Shortcuts
+    const key = this._key;
+    const keyWords = key.words;
+    const keySigBytes = key.sigBytes;
+
+    // Init sbox
+    this._S = [];
+    const S = this._S;
+    for (let i = 0; i < 256; i += 1) {
+      S[i] = i;
+    }
+
+    // Key setup
+    for (let i = 0, j = 0; i < 256; i += 1) {
+      const keyByteIndex = i % keySigBytes;
+      const keyByte = (keyWords[keyByteIndex >>> 2] >>> (24 - (keyByteIndex % 4) * 8)) & 0xff;
+
+      j = (j + S[i] + keyByte) % 256;
+
+      // Swap
+      const t = S[i];
+      S[i] = S[j];
+      S[j] = t;
+    }
+
+    // Counters
+    this._j = 0;
+    this._i = this._j;
+  }
+
+  _doProcessBlock(M, offset) {
+    const _M = M;
+
+    _M[offset] ^= generateKeystreamWord.call(this);
+  }
+}
+RC4Algo.keySize = 256 / 32;
+RC4Algo.ivSize = 0;
+
+/**
+ * Shortcut functions to the cipher's object interface.
+ *
+ * @example
+ *
+ *     var ciphertext = CryptoJS.RC4.encrypt(message, key, cfg);
+ *     var plaintext  = CryptoJS.RC4.decrypt(ciphertext, key, cfg);
+ */
+export const RC4 = StreamCipher._createHelper(RC4Algo);
+
+/**
+ * Modified RC4 stream cipher algorithm.
+ */
+export class RC4DropAlgo extends RC4Algo {
+  constructor(...args) {
+    super(...args);
+
+    /**
+     * Configuration options.
+     *
+     * @property {number} drop The number of keystream words to drop. Default 192
+     */
+    Object.assign(this.cfg, { drop: 192 });
+  }
+
+  _doReset() {
+    super._doReset.call(this);
+
+    // Drop
+    for (let i = this.cfg.drop; i > 0; i -= 1) {
+      generateKeystreamWord.call(this);
+    }
+  }
+}
+
+/**
+ * Shortcut functions to the cipher's object interface.
+ *
+ * @example
+ *
+ *     var ciphertext = CryptoJS.RC4Drop.encrypt(message, key, cfg);
+ *     var plaintext  = CryptoJS.RC4Drop.decrypt(ciphertext, key, cfg);
+ */
+export const RC4Drop = StreamCipher._createHelper(RC4DropAlgo);