(MFC) 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 C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkCert.h>
#include <CkPublicKey.h>

void ChilkatSample(void)
    {
    CkString strOut;

    CkCert 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) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Get the public key:
    CkPublicKey *pubKey = cert.ExportPublicKey();
    if (cert.get_LastMethodSuccess() != true) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        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".
    strOut.append("key type = ");
    strOut.append(pubKey->keyType());
    strOut.append("\r\n");

    delete pubKey;


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }