(C#) Convert RSA Private Key to Public Key

Demonstrates how to get a public RSA key from a private RSA key.

Note: This example requires Chilkat v11.0.0 or greater.

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bool success = false;

Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();

// Step 1: Load the private key from a source.
// (Chilkat can load private keys from all types of formats, and from in-memory bytes or encoded strings.
// see the online reference documentation for more options.)
success = privKey.LoadPemFile("qa_data/pem/VP_Private.pem");
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

// Step 2: Get the public key object from the private key object.
Chilkat.PublicKey pubKey = new Chilkat.PublicKey();
privKey.ToPublicKey(pubKey);

// Step 3: Save the public key in a desired format. 
// (Chilkat can load or save public and private keys in many different formats.  See
// the online reference documentation for more options.)

// Saves to a PKCS8 PEM file.
bool bPreferPkcs1 = false;
success = pubKey.SavePemFile(bPreferPkcs1,"qa_data/pem/VP_Public.pem");
if (pubKey.LastMethodSuccess == false) {
    Debug.WriteLine(pubKey.LastErrorText);
    return;
}

Debug.WriteLine("Extracted and saved public key from private key.");