(.NET Core C#) Export a Certificate's Private Key to Various Formats

Loads a digital certificate and private key from a PFX file (also known as PKCS#12) and exports the private key to various formats: (1) PKCS8 Encrypted, (2) PKCS8 Encrypted PEM, (3) PKCS8 unencrypted, (4) PKCS8 PEM unencrypted, (5) RSA DER unencrypted, (6) RSA PEM unencrypted, (7) XML.

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

// Load from the PFX file
string pfxFilename = "/Users/chilkat/testData/pfx/chilkat_ssl_pwd_is_test.pfx";
string pfxPassword = "test";

// A PFX typically contains certificates in the chain of authentication.
// The Chilkat cert object will choose the certificate w/
// private key farthest from the root authority cert.
// To access all the certificates in a PFX, use the 
// Chilkat certificate store object instead.
bool success = cert.LoadPfxFile(pfxFilename,pfxPassword);
if (success != true) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Get the private key...
Chilkat.PrivateKey privKey = null;
privKey = cert.ExportPrivateKey();
if (cert.LastMethodSuccess == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Export to various formats:

string password = "secret";
string path;

// PKCS8 Encrypted DER
path = "/Users/chilkat/testData/privkeys/chilkat_pkcs8_enc.der";
success = privKey.SavePkcs8EncryptedFile(password,path);
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);

    return;
}

// PKCS8 Encrypted PEM
path = "/Users/chilkat/testData/privkeys/chilkat_pkcs8_enc.pem";
success = privKey.SavePkcs8EncryptedPemFile(password,path);
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);

    return;
}

// PKCS8 Unencrypted DER
path = "/Users/chilkat/testData/privkeys/chilkat_pkcs8.der";
success = privKey.SavePkcs8File(path);
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);

    return;
}

// PKCS8 Unencrypted PEM
path = "/Users/chilkat/testData/privkeys/chilkat_pkcs8.pem";
success = privKey.SavePkcs8PemFile(path);
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);

    return;
}

//  RSA DER (unencrypted)
path = "/Users/chilkat/testData/privkeys/chilkat_rsa.der";
success = privKey.SavePkcs1File(path);
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);

    return;
}

// RSA PEM (unencrypted)
path = "/Users/chilkat/testData/privkeys/chilkat_rsa.pem";
success = privKey.SavePemFile(path);
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);

    return;
}

// XML (unencrypted)
path = "/Users/chilkat/testData/privkeys/chilkat.xml";
success = privKey.SaveXmlFile(path);
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);

    return;
}

Debug.WriteLine("Private key exported to all formats.");