Node.js new X509Certificate() Function

The new X509Certificate(buffer) is  an inbuilt constructor of class X509Certificate within crypto module which is used to provide a PEM encoded X509 Certificate.

Syntax:

new X509Certificate(buffer)

Parameters: This function takes the buffer of strings representing public certificate.

Return Value: This function returns the object of a PEM encoded X509 Certificate.

How to generate a Public certificate?

Public certificate: Open notepad and copy-paste the following key and save the file as public-cert.pem

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Example 1:

index.js

// Node.js program to demonstrate the
// new X509Certificate(buffer) constructor function

// Importing crypto module
const {X509Certificate} = require('crypto')

// Importing fs module
const fs = require('fs')

// getting object of a PEM encoded X509 Certificate.
const x509 = new X509Certificate(fs.readFileSync('public-cert.pem'));

// getting subject included in this certificate.
// by using x509.subject function
const value = x509.subject

// display the result
console.log("subject :- " + value)

Run the index.js file using the following command:

node index.js

Output:

subject :- C=IN
ST=Westbengal
L=Kolkata
O=Panco, Inc.
CN=Rohit Prasad
emailAddress=rofofof@gmail.com

Example 2:

index.js

// Node.js program to demonstrate the
// new X509Certificate(buffer) constructor function

// Importing crypto module
const {X509Certificate} = require('crypto')

// Importing fs module
const fs = require('fs')

// display the result
console.log((new X509Certificate(
             fs.readFileSync('public-cert.pem'))).subject)

Run the index.js file using the following command:

node index.js

Output:

C=IN
ST=Westbengal
L=Kolkata
O=Panco, Inc.
CN=Rohit Prasad
emailAddress=rofofof@gmail.com

Reference: https://nodejs.org/dist/latest-v15.x/docs/api/crypto.html#crypto_new_x509certificate_buffer