(.NET Core C#) RSA Sign Binary Data and Verify (Recover the Original Data)

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// Load an RSA private key for signing.
Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
bool success = privKey.LoadEncryptedPemFile("qa_data/pem/rsa_passwd.pem","passwd");
if (success != true) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

Chilkat.Rsa rsa = new Chilkat.Rsa();
rsa.ImportPrivateKeyObj(privKey);

// We have some binary data (in hex) to sign
string originalData = "0102030405060708090A";
Chilkat.BinData bd = new Chilkat.BinData();
bd.AppendEncoded(originalData,"hex");

// If successful, the contents of bd are replaced with the RSA signature.
success = rsa.OpenSslSignBd(bd);
if (success != true) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// Show the RSA signature in base64
Debug.WriteLine(bd.GetEncoded("base64"));

// ------------------------------------------
// Get the public key from the private key
Chilkat.PublicKey pubKey = privKey.GetPublicKey();

// Verify the signature and extract the original data.
Chilkat.Rsa rsa2 = new Chilkat.Rsa();
rsa2.ImportPublicKeyObj(pubKey);

bool bVerified = rsa2.OpenSslVerifyBd(bd);
Debug.WriteLine("signature verified: " + Convert.ToString(bVerified));

// Show the original data:
Debug.WriteLine("original data: " + bd.GetEncoded("hex"));