crypto.getDiffieHellman()

crypto.getDiffieHellman(group_name)

Creates a predefined DiffieHellman key exchange object. The supported groups are: 'modp1', 'modp2', 'modp5' (defined in RFC 2412, but see Caveats) and 'modp14', 'modp15', 'modp16', 'modp17', 'modp18' (defined in RFC 3526). The returned object mimics the interface of objects created by crypto.createDiffieHellman(), but will not allow changing the keys (with diffieHellman.setPublicKey() for example). The advantage of using this method is that the parties do not have to generate nor exchange a group modulus beforehand, saving both processor and communication time.

Example (obtaining a shared secret):

const crypto = require('crypto');
const alice = crypto.getDiffieHellman('modp14');
const bob = crypto.getDiffieHellman('modp14');

alice.generateKeys();
bob.generateKeys();

const alice_secret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bob_secret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

/* alice_secret and bob_secret should be the same */
console.log(alice_secret == bob_secret);