Node.js tlsSocket.getCipher() Method

The tlsSocket.getCipher() method is an inbuilt application programming interface of class TLSSocket within tls module which is used to return objects containing information on the negotiated cipher suite.

Syntax:

const tlsSocket.getCipher()

Parameters: This method does not accept any parameter.

Return Value: This method returns an object containing information on the negotiated cipher suite.

How to generate private keys and public certificates?

Private Key

Step 1: Open Notepad and copy-paste the following key:

Step 2: Save as a private key.pem

Public Certificate

Step 1: Open Notepad and copy-paste the following key:

Step 2: Save as public cert.pem

Example 1: Filename: index.js

Javascript

// Node.js program to demonstrate the
// tlsSocket.getCipher() method
const tls = require('tls'),
    fs = require('fs'),
 
    // Port and host address for server
    PORT = 1337,
    HOST = '127.0.0.1',
    value = null;
 
// Private key and public certificate
// for access
const options = {
    key: fs.readFileSync('private-key.pem'),
    cert: fs.readFileSync('public-cert.pem'),
    rejectUnauthorized: false
};
 
// Creating and initializing server
const server = tls.createServer(options,
    function (socket) {
 
        // Print the data that we received
        socket.on('data', function (data) {
            console.log('\nReceived: %s ',
                data.toString().replace(/(\n)/gm, ""));
        });
 
        // Stopping the server
        // by using the close() method
        server.close(() => {
            console.log("Server closed successfully");
        });
    });
 
// Start listening on a specific port
// and address by using listen() method
server.listen(PORT, HOST, function () {
    console.log(
        "I'm listening at %s, on port %s",
        HOST, PORT);
});
 
// Creating and initializing client
const client = tls.connect(PORT, HOST,
    options, function () {
 
        // Getting local cipher object by
        // using tlsSocket.getCipher() method
        value = client.getCipher();
 
        client.write("Cipher : " + value.name);
 
        client.end(() => {
            console.log("Client closed successfully");
        });
    });

Output:

I'm listening at 127.0.0.1, on port 1337
Client closed successfully

Received: Cipher : TLS_AES_256_GCM_SHA384
Server closed successfully

Example 2:Filename: index.js

Javascript

// Node.js program to demonstrate the
// tlsSocket.getCipher() method
const tls = require('tls'),
    fs = require('fs'),
 
    // Port and host address for server
    PORT = 1337,
    HOST = '127.0.0.1';
 
// Private key and public certificate
// for access
const options = {
    key: fs.readFileSync('private-key.pem'),
    cert: fs.readFileSync('public-cert.pem'),
    rejectUnauthorized: false
};
 
// Creating and initializing server
const server = tls.createServer(options,
    function (socket) {
 
        // Getting local cipher object
        // by using tlsSocket.getCipher() method
        value = socket.getCipher();
 
        socket.write("Cipher : " + value.name);
 
        // Stopping the server
        // by using the close() method
        server.close(() => {
            console.log("Server closed successfully")
        });
    });
 
// Start listening on a specific port
// and address by using listen() method
server.listen(PORT, HOST, function () {
    console.log("I'm listening at %s, "
        + "on port %s", HOST, PORT);
});
 
// Creating and initializing client
const client = tls.connect(PORT, HOST,
    options, function () {
        console.log("client is connected");
    });
 
client.on("data", function (data) {
 
    console.log('Received: %s',
        data.toString().replace(/(\n)/gm, ""));
 
    // Close the connection after
    // receiving the message
    client.end(() => {
        console.log("client closed successfully")
    });
});

Run the index.js file using the following command:

node index.js

Output:

I'm listening at 127.0.0.1, on port 1337
client is connected
Received: Cipher : TLS_AES_256_GCM_SHA384
client closed successfully
Server closed successfully

Reference: https://nodejs.org/dist/latest-v12.x/docs/api/tls.html#tls_tlssocket_getcipher

Javascript

Javascript

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