I am looking for a way to extract public key from certificate x509 (PEM format) in javascript like this one:

openssl x509 -in cert.cer -pubkey -noout > pub.txt

I am looking for a way to extract public key from certificate x509 (PEM format) in javascript like this one:

openssl x509 -in cert.cer -pubkey -noout > pub.txt

• javascript
• x509certificate
• public-key
• x509certificate2

3 Answers 3

var cert = forge.pki.certificateFromPem(pem); 
var pem = 
forge.pki.publicKeyToPem(cert.publicKey)

Thanks halloulaguesmi. This seems to be working perfectly.

You need something that can parse ASN.1 structure. You could use pkijs.

Demo can be found here

After Node.js v15.6.0, you could use publicKey of X509Certificate from crypto module to retrieve the public key.

If you want to export publicKey, the export could be used

For public keys, the following encoding options can be used:

• type: Must be one of 'pkcs1' (RSA only) or 'spki'.
• format: Must be 'pem', 'der', or 'jwk'.

Sample codes

const crypto = require("crypto")

const cert = new crypto.X509Certificate("pem file content"))

console.log(cert.publicKey.export({"type": "pkcs1", "format": "jwk"}));