C#

Generate RSA Key and Sign a String

See more RSA Examples

Demonstrates how to generate a new RSA public/private key pair and use it to generate a signature for a string. The (binary) digital signature is returned as a hexidecimalized string. C#

bool success = false;

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

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

// Generate a 2048-bit RSA key.
Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
success = rsa.GenKey(2048,privKey);

rsa.UsePrivateKey(privKey);

// Return the signature in hex.
rsa.EncodingMode = "hex";

string strData = "This is the string to be signed.";

// Sign the SHA256 hash of the string.
string hexSig = rsa.SignStringENC(strData,"sha256");

Debug.WriteLine(hexSig);

// Now verify the signature:
Chilkat.PublicKey pubKey = new Chilkat.PublicKey();
privKey.ToPublicKey(pubKey);
rsa.UsePublicKey(pubKey);

success = rsa.VerifyStringENC(strData,"sha256",hexSig);
if (success == true) {
    Debug.WriteLine("Signature verified!");
}
else {
    Debug.WriteLine(rsa.LastErrorText);
}

// Try it with an invalid signature:
success = rsa.VerifyStringENC(strData,"sha256","not a valid sig");
if (success == true) {
    Debug.WriteLine("Signature verified!");
}
else {
    Debug.WriteLine("Signature validation failed!");
}

// Try it with invalid data:
success = rsa.VerifyStringENC("Not the original data","sha256",hexSig);
if (success == true) {
    Debug.WriteLine("Signature verified!");
}
else {
    Debug.WriteLine("Signature validation failed!");
}