Generate RSA Key and Sign a String

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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.

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

//  Any string argument automatically begins the 30-day trial.
bool success;
success = rsa.UnlockComponent("30-day trial");
if (success != true) {
    MessageBox.Show("RSA component unlock failed");
    return;
}

//  Generate a 1024-bit RSA key pair.
rsa.GenerateKey(1024);

//  This example will sign a string, and receive the signature
//  in a hex-encoded string.  Therefore, set the encoding mode
//  to "hex":
rsa.EncodingMode = "hex";

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

//  Sign the string using the  md5 hash algorithm.
//  Other valid choices are "md2" and "sha-1".
string hexSig;
hexSig = rsa.SignStringENC(strData,"md5");

textBox1.Text += hexSig + "\r\n";
textBox1.Text += rsa.LastErrorText + "\r\n";

//  Now verify the signature:
success = rsa.VerifyStringENC(strData,"md5",hexSig);
if (success == true) {
    MessageBox.Show("Signature verified!");
}
else {
    textBox1.Text += rsa.LastErrorText + "\r\n";
}

//  Try it with an invalid signature:
success = rsa.VerifyStringENC(strData,"md5","not a valid sig");
if (success == true) {
    MessageBox.Show("Signature verified!");
}
else {
    textBox1.Text += rsa.LastErrorText + "\r\n";
}

//  Try it with invalid data:
success = rsa.VerifyStringENC("Not the original data","md5",hexSig);
if (success == true) {
    MessageBox.Show("Signature verified!");
}
else {
    textBox1.Text += rsa.LastErrorText + "\r\n";
}

//  Try it with the wrong hash algorithm:
success = rsa.VerifyStringENC(strData,"sha-1",hexSig);
if (success == true) {
    MessageBox.Show("Signature verified!");
}
else {
    textBox1.Text += rsa.LastErrorText + "\r\n";
}