lab12: init

lab12/signingExample.js

@@ -0,0 +1,51 @@
+var crypto = require('crypto');
+var fs = require('fs');
+var events = require('events');
+
+function Signer(privKeyFile) {
+  // Reads in and stores the private key
+  this.privateKey = fs.readFileSync(privKeyFile).toString('ascii');
+}
+
+Signer.prototype.signMessage = function(messageFileName) {
+  // Read in the file
+  var msg = fs.readFileSync(messageFileName).toString('ascii');
+  // Specify which signing algorithm we want to use
+  var sign = crypto.createSign('RSA-SHA256');
+  // Sign the message and return the signature in hexadecimal form
+  return sign.update(msg).sign(this.privateKey,'hex');
+}
+
+
+function Verifier(pubKeyFile) {
+  // Reads in and stores the public key
+  this.publicKey = fs.readFileSync(pubKeyFile).toString('ascii');
+}
+Verifier.prototype = new events.EventEmitter();
+
+Verifier.prototype.verifySignature = function(messageFileName, signature) {
+  // Read in the file
+  var msg = fs.readFileSync(messageFileName).toString('ascii');
+  // Test the signature
+  var legit = crypto.createVerify('RSA-SHA256').update(msg)
+                   .verify(this.publicKey, signature, 'hex');
+  if (legit) {
+    console.log("Signature is valid");
+  } else {
+    console.log("Invalid signature");
+  }
+}
+
+var verifier = new Verifier('./keys/charliePub.txt');
+Verifier.prototype.on('signing', verifier.verifySignature);
+
+// Valid signing
+var signer = new Signer('./keys/charliePriv.txt');
+var signature = signer.signMessage('./message.txt');
+verifier.emit('signing', './message.txt', signature);
+
+// Wrong signature used
+signer = new Signer('./keys/bobPriv.txt');
+signature = signer.signMessage('./message.txt');
+verifier.emit('signing', './message.txt', signature);
+