Node.js tlsSocket.exportKeyingMaterial() Method

The tlsSocket.exportKeyingMaterial() is an inbuilt application programming interface of class TLSSocket within tls module which is used to return the requested bytes of the keying material to prevent different kind of attacks in network protocols.

Syntax:

const tlsSocket.exportKeyingMaterial(length, label[, context])

Parameters: This method takes the following argument as parameter:

• length: It is the number of bytes.
• label: It’s an application specific label.
• context: Context for generating the keying material.

Return Value: This method returns the buffer containing the keying material.

How to generate Private key and Public certificate?

• Private key: Open notepad and copy paste the following key:

  -----BEGIN RSA PRIVATE KEY-----
  MIICXQIBAAKBgQC38R9wXcUbhOd44FavgmE5R3K4JeYOHLnI7dUq1B8/Gv7l3SOg
  JKef/m9gM1KvUx951mapXGtcWgwB08J3vUE2YOZ4tWJArrVZES0BI/RmFAyhQFP5
  HcWl3LSM9LRihP98F33oIkKaCxA5LxOrkgpV4HrUzIKTABDYah7RPex1WQIDAQAB
  AoGBAIXR71xxa9gUfc5L7+TqBs+EMmrUb6Vusp8CoGXzQvRHMJCMrMFySV0131Nu
  o0YYRDsAh1nJefYLMNcXd1BjqI+qY8IeRsxaY+9CB2KKGVVDO2uLdurdC2ZdlWXT
  Vwr3dDoyR0trnXJMmH2ijTeO6bush8HuXxvxJBjvEllM5QYxAkEA3jwny9JP+RFu
  0rkqPBe/wi5pXpPl7PUtdNAGrh6S5958wUoR4f9bvwmTBv1nQzExKWu4EIp+7vjJ
  fBeRZhnBvQJBANPjjge8418PS9zAFyKlITq6cxmM4gOWeveQZwXVNvav0NH+OKdQ
  sZnnDiG26JWmnD/B8Audu97LcxjxcWI8Jc0CQEYA5PhLU229lA9EzI0JXhoozIBC
  TlcKFDuLm88VSmlHqDyqvF9YNOpEdc/p2rFLuZS2ndB4D+vu6mjwc5iZ3HECQCxy
  GBHRclQ3Ti9w76lpv+2kvI4IekRMZWDWnnWfwta+DGxwCgw2pfpleBZkWqdBepb5
  JFQbcxQJ0wvRYXo8qaUCQQCgTvWswBj6OTP7LTvBlU1teAN2Lnrk/N5AYHZIXW6m
  nUG9lYvH7DztWDTioXMrruPF7bdXfZOVJD8t0I4OUzvC
  -----END RSA PRIVATE KEY-----
  

  Now save the filename as private-key.pem

• Public certificate: Open notepad and copy paste the following key:

  -----BEGIN CERTIFICATE-----
  MIICfzCCAegCCQDxxeXw914Y2DANBgkqhkiG9w0BAQsFADCBgzELMAkGA1UEBhMC
  SU4xEzARBgNVBAgMCldlc3RiZW5nYWwxEDAOBgNVBAcMB0tvbGthdGExFDASBgNV
  BAoMC1BhbmNvLCBJbmMuMRUwEwYDVQQDDAxSb2hpdCBQcmFzYWQxIDAeBgkqhkiG
  9w0BCQEWEXJvZm9mb2ZAZ21haWwuY29tMB4XDTIwMDkwOTA1NTExN1oXDTIwMTAw
  OTA1NTExN1owgYMxCzAJBgNVBAYTAklOMRMwEQYDVQQIDApXZXN0YmVuZ2FsMRAw
  DgYDVQQHDAdLb2xrYXRhMRQwEgYDVQQKDAtQYW5jbywgSW5jLjEVMBMGA1UEAwwM
  Um9oaXQgUHJhc2FkMSAwHgYJKoZIhvcNAQkBFhFyb2ZvZm9mQGdtYWlsLmNvbTCB
  nzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAt/EfcF3FG4TneOBWr4JhOUdyuCXm
  Dhy5yO3VKtQfPxr+5d0joCSnn/5vYDNSr1MfedZmqVxrXFoMAdPCd71BNmDmeLVi
  QK61WREtASP0ZhQMoUBT+R3Fpdy0jPS0YoT/fBd96CJCmgsQOS8Tq5IKVeB61MyC
  kwAQ2Goe0T3sdVkCAwEAATANBgkqhkiG9w0BAQsFAAOBgQATe6ixdAjoV7BSHgRX
  bXM2+IZLq8kq3s7ck0EZrRVhsivutcaZwDXRCCinB+OlPedbzXwNZGvVX0nwPYHG
  BfiXwdiuZeVJ88ni6Fm6RhoPtu2QF1UExfBvSXuMBgR+evp+e3QadNpGx6Ppl1aC
  hWF6W2H9+MAlU7yvtmCQQuZmfQ==
  -----END CERTIFICATE-----
  

  Now save the filename as public-cert.pem

Example 1: Filename: index.js

// Node.js program to demonstrate the
// tlsSocket.exportKeyingMaterial() method
var 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
var options = {
  key: fs.readFileSync('private-key.pem'),
  cert: fs.readFileSync('public-cert.pem'),
  rejectUnauthorized: false
};

// Creating and initializing server
var 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
var client = tls.connect(PORT, HOST, options, function() {

  // Getting keying material
  // by using tlsSocket.exportKeyingMaterial() method
  value = client.exportKeyingMaterial(
  128, 'client finished');

  client.write("keying material : " + value.toJSON().data);

  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 closed successfully

Received: keying material : 10, 183, 131,....... 52, 121, 159
Server closed successfully

Example 2: Filename: index.js

// Node.js program to demonstrate the
// tlsSocket.exportKeyingMaterial() method
var 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
var options = {
  key: fs.readFileSync('private-key.pem'),
  cert: fs.readFileSync('public-cert.pem'),
  rejectUnauthorized: false
};

// Creating and initializing server
var server = tls.createServer(options, function(socket) {

  // Getting keying material
  // by using tlsSocket.exportKeyingMaterial() method
  value = socket.exportKeyingMaterial(
  128, 'server finished');;

  socket.write("keying material : " + 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
var 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: keying material : 239, 29, 74, 173 .... 209, 242, 131
client closed successfully
Server closed successfully

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