C#

RSA Hash Binary Data and Sign (and Verify)

See more RSA Examples

Demonstrates how to sign the hash of binary data. Also demonstrates how to verify the RSA signature. C#

bool success = false;

// 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();
success = privKey.LoadEncryptedPemFile("qa_data/pem/rsa_passwd.pem","passwd");
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

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

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

// Hash (SHA-256) and sign the hash:
Chilkat.BinData bdSignature = new Chilkat.BinData();
success = rsa.SignBd(bdData,"sha256",bdSignature);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

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

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

// Verify the signature..
Chilkat.Rsa rsa2 = new Chilkat.Rsa();
rsa2.UsePublicKey(pubKey);

bool bVerified = rsa2.VerifyBd(bdData,"sha256",bdSignature);
Debug.WriteLine("signature verified: " + Convert.ToString(bVerified));