Node.js tlsSocket.getPeerFinished() Method

The tlsSocket.getPeerFinished() method is an inbuilt application programming interface of class TLSSocket within tls module which is used to return the latest Finished message that has been sent to the socket as part of a SSL/TLS handshake, or undefined if no Finished message has been sent yet.

Syntax:

const tlsSocket.getPeerFinished()

Parameters: This method does not accept any parameter.

Return Value: This method returns a buffer object containing message digests of the complete handshake.

How to generate private keys and public certificates?

Private key: Open Notepad and copy-paste the following key: 

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

Save the file as a private key.pem

Public certificate: Open Notepad and copy and paste the following key:  

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Save file as public-cert.pem
Example 1: Filename: index.js

javascript

// Node.js program to demonstrate the
// tlsSocket.getPeerFinished() 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 finished message digest
        // by using tlsSocket.getPeerFinished()
        // method
        value = client.getPeerFinished();

        client.write("Finisher message : "
            + value.toJSON().data);

        client.end(() => {
            console.log("Client closed successfully");
        });
    });

Output:

I’m listening at 127.0.0.1, on port 1337 
Client closed successfully
Received: Finisher message : 133, 120, 218, 179, 42, 34, 167, 40, 96, 3, 66, 211, 61, 190, 255, 206, 180, 162, 245, 65, 237, 69, 57, 234, 179, 148, 65, 62, 113, 30, 160, 106, 134, 175, 176, 198, 52, 25, 248, 25, 76, 129, 167, 159, 166, 241, 2, 97 
Server closed successfully

Example 2: Filename: index.js

javascript

// Node.js program to demonstrate the
// tlsSocket.getPeerFinished() 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 finished message digest
        // by using tlsSocket.getPeerFinished()
        // method
        value = socket.getPeerFinished();

        socket.write("Finisher message : "
            + value.toJSON().data);

        // 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: Finisher message : 114, 99, 193, 23, 71, 139, 48, 221, 208, 160, 177, 63, 186, 157, 188, 76, 188, 83, 85, 24, 2, 10, 53, 8, 21, 150, 189, 35, 162, 118, 153, 232, 246, 60, 18, 225, 24, 29, 4, 113, 16, 126, 156, 69, 105, 16, 24, 151 
client closed successfully 
Server closed successfully 

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