React Native Requires Chilkat v11.0.0+

About RSA Public/Private Keys

See more RSA Examples

This example provides some additional information for understanding public/private key pairs. In demonstrates how a private key is a superset of the public key. A public key contains the modulus and exponent. The matching private key also contains the modulus and exponent, but also contains the additional private key parts. React Native

import { Cert, PrivateKey, PublicKey } from '@chilkat/react-native'

function chilkatExample() {
  const cert = new Cert();

  // Load a digital certificate.
  try {
    cert.loadFromFile('digitalCert.cer');
  } catch {
    console.log(cert.lastErrorText);
    return;
  }

  // A .cer file does not contain the private key.  It should contain
  // the public key...
  const pubKey = new PublicKey();
  cert.getPublicKey(pubKey);

  // Let's have a look at it (in XML format).
  console.log('Public Key from Certificate:');
  console.log(pubKey.getXml());

  // An RSA public key consists of a modulus and exponent.

  // An RSA private key includes both the modulus and exponent,
  // as well as other "big" numbers: P, Q, D, etc.

  // Let's load an RSA private key from a DER-encoded file:
  const privKey = new PrivateKey();

  try {
    privKey.loadAnyFormatFile('PrivateKey.key', '');
  } catch {
    console.log(privKey.lastErrorText);
    return;
  }

  // If this private key is the matching half to the public key from
  // the certificate, then the modulus and exponent should
  // be identical.  (Thus, a "private key" really contains both the public part as well as the private parts...).
  console.log('Private Key from DER:');
  console.log(privKey.getXml());
}