Added RC4/MD4 alternatives for NodeJS v17, #

rdp/security/rc4.js

@@ -0,0 +1,70 @@
+
+function RC4(key) {
+    this.privateKey = keySetup(key);
+    this.byteStream = byteStreamGenerator(this.privateKey.slice(0));
+}
+
+/**
+ * Converts the text into an array of the characters numeric Unicode values
+ * @param  {String} text, the text to convert
+ * @return {Array} the array of Unicode values
+ */
+function convert(text) {
+    var codes = [];
+    for (var i = 0, ii = text.length; i < ii; i++) { codes.push(text.charCodeAt(i)); }
+    return codes;
+}
+
+/**
+ * Sets up the key to use with the byte stream
+ * @param  {String} key, The key that you want to use
+ * @return {Array}, the key stream which with be used in the byteStreamGenerator
+ */
+function keySetup(key) {
+    var K = [...Array(256).keys()], j = 0, key = convert(key);
+    for (var i = 0, ii = K.length; i < ii; i++) {
+        j = (j + K[i] + key[i % key.length]) % 256;
+        [K[i], K[j]] = [K[j], K[i]];
+    }
+    return K;
+}
+
+/**
+ * byteStreamGenerator uses ES6 generators which will be 'XOR-ed' to encrypt and decrypt
+ * @param {Array} K, the array generated from the keySetup
+ * @yield {Integer}, the current value which will be 'XOR-ed' to encrypt or decrypt
+ */
+var byteStreamGenerator = function* (K) {
+    var i = 0, j = 0;
+    while (true) {
+        i = (i + 1) % 256;
+        j = (j + K[i]) % 256;
+        [K[i], K[j]] = [K[j], K[i]];
+        yield (K[(K[i] + K[j]) % 256]);
+    }
+}
+
+/**
+ * Encrypts the input text
+ * @param  {String} input, the text to encrypt
+ * @return {String}, the encrypted text
+ */
+RC4.prototype.encrypt = function (input) {
+    var outputText = '';
+    for (var i = 0, ii = input.length; i < ii; i++) { outputText += ('00' + (input.charCodeAt(i) ^ this.byteStream.next().value).toString(16)).substr(-2); }
+    return outputText;
+}
+
+/**
+ * Decrypts the input text
+ * @param  {String} input, the text to decrypt
+ * @return {String}, the decrypted text (if the same key was used)
+ */
+RC4.prototype.decrypt = function (input) {
+    var outputText = '';
+    input = input.match(/[a-z0-9]{2}/gi);
+    for (var i = 0, ii = input.length; i < ii; i++) { outputText += String.fromCharCode((parseInt(input[i], 16) ^ byteStream.next().value)); }
+    return outputText;
+}
+
+module.exports = RC4;