Node.js DiffieHellmanGroup Class

In this article, we will discuss the DiffieHellmanGroup class, which is accessible in the Node.js crypto module. We may utilize the various groups and commute the secret keys of the sender and receiver thanks to the DiffieHellmanGroup Class. The shared key bit groups will be used in the key exchange between the sender and recipient. The Diffie-Hellman algorithm is based on a large prime number (P) and a generator ( G ). P’s primitive root is G.

Primitive root: Let G is the primitive root of prime P then – G is an integer between [ 1, P – 1 ] and X is an integer between [ 1, P – 2 ] such that the value of  G^{X mod P}  is different for each X value.

The following are the Diffie-Hellman groups:

SR.No.	Group	Bits
1	modp14	2048 bits
2	modp15	3072 bits
3	modp16	4096 bits
4	modp17	6144 bits
5	modp18	8192 bits

The bits here represent the length of the prime number. If we use the mod14 group to compute the shared secret keys, the prime number will be 2048 bits long.

The security of the system will depend on the length of the prime number. Suppose you are using the mod18 group then the system will be more secure compared to the above groups.

Example 1: In this example, we will use the modp14 group and compute the shared secret key for Alice and Bob. We first create the DiffieHellmanGroup objects for both of them and generate the public and private keys using the generateKeys() method. After that, we calculate the shared secret keys for both the sender and receiver using their previously created public keys. Finally, we compare both shared secret keys. If both keys are the same means a secret key is shared successfully between the sender and receiver.

Javascript

// Importing the getDiffieHellman from crypto module
const { getDiffieHellman } = require('node:crypto');

// Creating DiffieHellmanGroup object for alice
let alice = getDiffieHellman('modp14');

// Creating DiffieHellmanGroup object for bob
let bob = getDiffieHellman('modp14');

// Generates private and public Diffie-Hellman
// key values, and returns the public key in
// the specified encoding for alice and bob
alice.generateKeys();
bob.generateKeys();

// Computes the shared secret using
// public keys for alice and bob
let AliceSecret =
    alice.computeSecret(bob.getPublicKey(), null, 'hex');

let BobSecret =
    bob.computeSecret(alice.getPublicKey(), null, 'hex');

// Alice shared secret key
console.log(AliceSecret);

// Bob shared secret key
console.log(BobSecret);

// Print true if both secret keys are same
console.log(AliceSecret == BobSecret);

Output:

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

true

Example 2: In this example, we will use the modp18 group and compute the shared secret key for Alice and Bob.

Javascript

// Importing the getDiffieHellman from crypto module
const { getDiffieHellman } = require('node:crypto');

// Creating DiffieHellmanGroup object for alice
let alice = getDiffieHellman('modp18');

// Creating DiffieHellmanGroup object for bob
let bob = getDiffieHellman('modp18');

// Generates private and public Diffie-Hellman key values,
// and returns the public key in the specified encoding for
// alice and bob
alice.generateKeys();
bob.generateKeys();

// Computes the shared secret using
// public keys for alice and bob
let AliceSecret =
    alice.computeSecret(bob.getPublicKey(), null, 'hex');

let BobSecret =
    bob.computeSecret(alice.getPublicKey(), null, 'hex');

// Alice shared secret key
console.log(AliceSecret);

// Bob shared secret key
console.log(BobSecret);

// Print true if both secret keys are same
console.log(AliceSecret == BobSecret);

Output:

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

true

Reference: https://nodejs.org/api/crypto.html#class-diffiehellmangroup