Axios SSL Certificate Pinning

axios.js

const tls = require('tls');
const https = require('https');
const crypto = require('crypto');
const axios = require('axios');

function sha256(s) {
  return crypto.createHash('sha256').update(s).digest('base64');
}

const options = {
  rejectUnauthorized: true,
  checkServerIdentity: function(host, cert) {
    // Make sure the certificate is issued to the host we are connected to
    const err = tls.checkServerIdentity(host, cert);
    if (err) {
      return err;
    }

    // Pin the public key, similar to HPKP pin-sha25 pinning
    const pubkey256 = 'ORH27mxcLwxnNpR7e0i6pdDPWLXdpeWgr5bEfFVbxW8=';
    if (sha256(cert.pubkey) !== pubkey256) {
      return new Error('Certificate verification error');
    }

    // OR Pin the exact certificate, rather than the pub key
    const cert256 = '3A:AE:0A:71:39:2F:86:22:5E:F2:9F:A9:FE:0C:66:BD:' +
      '8A:85:AB:F5:C6:8F:F2:D1:E3:33:A8:EF:6F:EB:52:87';
    if (cert.fingerprint256 !== cert256) {
      return new Error('Certificate verification error');
    }
  },
};

const agent = new https.Agent(options);

axios.get('https://api.github.com', { httpsAgent: agent })
.then(response => {
    console.log('All OK. Server matched our pinned cert or public key')
})
.catch(error => {
    console.error(error.message)
});

Can't call to function checkServerIdentity.

Hi Team,

What is cert parameter in the function.How to get cert?.

Thank you.