Node.js TLS/SSL

What is TLS/SSL

TLS stands for Transport Layer Security. It is the successor to Secure Sockets Layer (SSL). TLS along with SSL is used for cryptographic protocols to secure communication over the web.

TLS uses public-key cryptography to encrypt messages. It encrypts communication generally on the TCP layer.

What is public-key cryptography

In public-key cryptography, each client and each server has two keys: public key and private key. Public key is shared with everyone and private key is secured. To encrypt a message, a computer requires its private key and the recipient?s public key. On the other hand, to decrypt the message, the recipient requires its own

You have to use require('tls') to access this module.

Syntax:

snippet

var tls = require('tls');

The tls module uses OpenSSL to attain Transport Layer Security and Secure Socket Layer. TLS/SSL is a public/private key infrastructure. Each client and each server must have a private key.

A private key can be created like this:

snippet

openssl genrsa -out ryans-key.pem 1024

All severs and some clients need to have a certificate. Certificates are public keys signed by a Certificate Authority or self-signed. To get certificate, you have to create a "Certificate Signing Request" (CSR) file.

A certificate can be created like this:

snippet

openssl req -new -key ryans-key.pem -out ryans-csr.pem

To create a self-signed certificate with the CSR:

snippet

openssl x509 -req -in ryans-csr.pem -signkey ryans-key.pem -out ryans-cert.pem

Node.js TLS client example

File: tls_client.js

snippet

tls = require('tls');
function connected(stream) {
    if (stream) {
       // socket connected
      stream.write("GET / HTTP/1.0\n\rHost: encrypted.google.com:443\n\r\n\r");  
    } else {
      console.log("Connection failed");
    }
}
 // needed to keep socket variable in scope
var dummy = this;
 // try to connect to the server
dummy.socket = tls.connect(443, 'encrypted.google.com', function() {
   // callback called only after successful socket connection
   dummy.connected = true;
   if (dummy.socket.authorized) {
      // authorization successful
      dummy.socket.setEncoding('utf-8');
      connected(dummy.socket);
   } else {
      // authorization failed
     console.log(dummy.socket.authorizationError);
     connected(null);
   }
});
 dummy.socket.addListener('data', function(data) {
   // received data
   console.log(data);
});
 dummy.socket.addListener('error', function(error) {
   if (!dummy.connected) {
     // socket was not connected, notify callback
     connected(null);
   }
   console.log("FAIL");
   console.log(error);
});
 dummy.socket.addListener('close', function() {
 // do something
});

Output: