(C#) How to Parse a X.509 Certificate and Extract its Public Key

Demonstrates how to load an X.509 certificate and extract the public key. Chilkat supports many certificate encodings:

• DER (binary) encoded certificates (.crt/.cer)
• PEM (BASE64) encoded certificates (.pem)
• Load Certificates Directly from Windows Certificate Stores
• PFX/PKCS12 (.pfx/.p12)
• Java KeyStore (.jks)
• Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

Chilkat.Cert cert = new Chilkat.Cert();

// Load a DER (binary) encoded certificate.
// To load from a .pem or .p7b, or any other file format that contains
// just one certificate, call LoadFromFile in exactly the same way.
// The LoadFromFile method automatically detects the format and loads the certificate.
bool success = cert.LoadFromFile("qa_data/certs/testCert.cer");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Get the public key:
Chilkat.PublicKey pubKey = cert.ExportPublicKey();
if (cert.LastMethodSuccess != true) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Examine the key type.
// A PublicKey object can contain an RSA, ECC, or DSA public key.
// The KeyType property will contain "rsa", "ecc", or "dsa".
Debug.WriteLine("key type = " + pubKey.KeyType);