Node.js diffieHellman.setPrivateKey() Method

The diffieHellman.setPrivateKey() method is an inbuilt application programming interface of class DiffieHellman (dh) within the crypto module which is used to set the private key of dh object.

Syntax:

diffieHellman.setPrivateKey(privateKey[, encoding])

Parameters: This method accepts the following two parameters:

privateKey: It is used to denote the private Key.
encoding: It is used to denote the encoding of privateKey. If encoding is provided privateKey expected to be String otherwise Buffer, TypedArray, or DataView.

Example 1:

index.js

// Node.js program to demonstrate the 
// diffieHellman.setPrivateKey() Method 

const crypto = require('crypto') 

// Generate DH Key pair 

crypto.generateKeyPair('dh',  

    { 

        primeLength: 512, 

         publicKeyEncoding: { 

            type: 'spki', 

            format: 'der'

        }, 

        privateKeyEncoding: { 

            type: 'pkcs8', 

            format: 'der'

        } 

    }, 

    cb 
) 

function cb(err, publicKey, privateKey){ 

    // Create Diffie-Hellman instance 

    const dh = crypto.createDiffieHellman(512) 

    // Set the dh's privateKey 

    dh.setPrivateKey(privateKey) 

    if( privateKey.equals(dh.getPrivateKey()) ) 

        console.log("DH private Key is set successfully") 
}

Run index.js file using the following command

node index.js

Output:

DH private Key is set successfully

Example 2 :

index.js

// Node.js program to demonstrate the 
// diffieHellman.setPrivateKey() Method 

const crypto = require( 'crypto' ) 

crypto.generateKeyPair(  

    'dh',  

    { primeLength: 512 },  

    cb  
) 

function cb( err, publicKey, privateKey ){ 

    // Export key from KeyObject 

    privateKey = privateKey.export( {type: 'pkcs8', format: 'der'} ) 

    // Encode key in base64 

    privateKey = privateKey.toString('base64'); 

    // Create Diffie-Hellman instance 

    const dh = crypto.createDiffieHellman( 512 ) 

    // Set the dh's privateKey 

    dh.setPrivateKey( privateKey, 'base64' ) 

    if( privateKey === dh.getPrivateKey('base64')  ) 

        console.log( "DH private Key is set successfully" ) 
}