Save a Private Key as an Encrypted PKCS #8 DER File

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Demonstrates the Chilkat PrivateKey.SavePkcs8EncryptedFile method, which saves the key as password-protected PKCS #8 DER. The first argument is the password and the second is the destination path. The cipher is selected by Pkcs8EncryptAlg.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: This is the recommended way to persist a key to disk: the binary .der is encrypted under a passphrase, so a stolen file is useless without it. Reach for it whenever a key is stored or shipped. Choose the encryption cipher with Pkcs8EncryptAlg and source the password securely.

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bool success = false;

//  Load a private key to export.
Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
success = privKey.LoadPemFile("qa_data/private.pem");
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

//  The key password is not hard-coded in a real application; obtain it from an interactive
//  prompt, environment variable, or a secrets vault.
string password = "myKeyPassword";

//  Save as password-protected PKCS #8 DER.  The 1st argument is the password and the 2nd is the
//  destination path.  The cipher is selected by the Pkcs8EncryptAlg property.
success = privKey.SavePkcs8EncryptedFile(password,"qa_output/private_pkcs8_enc.der");
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

Debug.WriteLine("Saved (encrypted).");