Node.js crypto.createDiffieHellman(prime, primeEncoding, generator, generatorEncoding) Method

The crypto.createDiffieHellman() method is used to create a DiffieHellman key exchange object by using the stated prime and an optional specified generator.
Syntax:

crypto.createDiffieHellman( prime, primeEncoding,
                        generator, generatorEncoding )

Parameters: This method accept four parameters as mentioned above and described below: 

• prime: It can hold string, Buffer, TypedArray, or DataView type of elements.
• primeEncoding: It is the encoding of the prime string and is of type string. 
  
• generator: It can hold number, string, Buffer, TypedArray, or DataView type of data. Its default value is 2.
• generatorEncoding: It is the encoding of the generator string and returns string.

Return Value: It returns DiffieHellman key exchange object.
Below examples illustrate the use of crypto.createDiffieHellman() method in Node.js:
Example 1:

javascript

// Node.js program to demonstrate the
// crypto.createDiffieHellman() method

// Including crypto module
const crypto = require('crypto');

// Creating DiffieHellman with prime
const alice = crypto.createDiffieHellman(20);

// Generate keys
alice.generateKeys();

// Creating DiffieHellman to get
// prime and generator
const bob= crypto.createDiffieHellman(
      alice.getPrime(), alice.getGenerator());
bob.generateKeys();

// Prints prime and generator for
// Alice with encoding
console.log("Alice prime (p):",
    alice.getPrime().toString('hex'),
    "\nAlice generator (G):",
    alice.getGenerator().toString('hex')
);

Output:

Alice prime (p): 0a134b
Alice generator (G): 02

Example 2:

javascript

// Node.js program to demonstrate the
// crypto.createDiffieHellman() method

// Including crypto module
const crypto = require('crypto');

// Creating DiffieHellman with prime
const k = crypto.createDiffieHellman(30);

// Accessing prime value
const p = k.getPrime();

// Accessing generator value
const g = k.getGenerator();

// Prints prime value
console.log(p);

// Prints generator value
console.log(g);

Output:

// Buffer 22 4a 58 5b
// Buffer 02

Therefore, both prime and generator returns buffer.
Reference: https://nodejs.org/api/crypto.html#crypto_crypto_creatediffiehellman_prime_primeencoding_generator_generatorencoding