Create Basic256.js

Author: linuxgemini

Basic256.js

@@ -0,0 +1,81 @@
+// HELP ME MAKE THIS SHITTY CIPHER API GREAT AGAIN //
+
+crypto = require('crypto');
+
+function randomValueHex (len) {
+    return crypto.randomBytes(Math.ceil(len/2))
+        .toString('hex') // convert to hexadecimal format
+        .slice(0,len);   // return required number of characters
+};
+
+var key1, ALGORITHM, KEY, HMAC_ALGORITHM, HMAC_KEY;
+
+ALGORITHM = 'AES-256-CBC'; // CBC because CTR isn't possible with the current version of the Node.JS crypto library
+HMAC_ALGORITHM = 'SHA256';
+KEY = randomValueHex(32); // This key should be stored in an environment variable
+HMAC_KEY = randomValueHex(32); // This key should be stored in an environment variable
+
+var constant_time_compare = function (val1, val2) {
+    var sentinel;
+
+    if (val1.length !== val2.length) {
+        return false;
+    }
+
+
+    for (var i = 0; i <= (val1.length - 1); i++) {
+        sentinel |= val1.charCodeAt(i) ^ val2.charCodeAt(i);
+    }
+
+    return sentinel === 0
+};
+
+module.exports = {
+
+    "enc": {
+        run : function (plain_text) {
+
+            var IV = new Buffer(randomValueHex(16)); // ensure that the IV (initialization vector) is random
+            var cipher_text;
+            var hmac;
+            var encryptor;
+
+            encryptor = crypto.createCipheriv(ALGORITHM, KEY, IV);
+            encryptor.setEncoding('hex');
+            encryptor.write(plain_text);
+            encryptor.end();
+
+            cipher_text = encryptor.read();
+
+            hmac = crypto.createHmac(HMAC_ALGORITHM, HMAC_KEY);
+            hmac.update(cipher_text);
+            hmac.update(IV.toString('hex')); // ensure that both the IV and the cipher-text is protected by the HMAC
+
+            // The IV isn't a secret so it can be stored along side everything else
+            return cipher_text + "$" + IV.toString('hex') + "$" + hmac.digest('hex') 
+        }
+    },
+
+    "dec": {
+        run : function (cipher_text) {
+            var cipher_blob = cipher_text.split("$");
+            var ct = cipher_blob[0];
+            var IV = new Buffer(cipher_blob[1], 'hex');
+            var hmac = cipher_blob[2];
+            var decryptor;
+
+            chmac = crypto.createHmac(HMAC_ALGORITHM, HMAC_KEY);
+            chmac.update(ct);
+            chmac.update(IV.toString('hex'));
+
+            if (!constant_time_compare(chmac.digest('hex'), hmac)) {
+                console.log("Encrypted Blob has been tampered with...");
+                return null;
+            }
+
+            decryptor = crypto.createDecipheriv(ALGORITHM, KEY, IV);
+            var decryptedText = decryptor.update(ct, 'hex', 'utf8');
+            return decryptedText + decryptor.final('utf-8');
+        }
+    }
+}