RSA Signature with Certificate's Private Key from PFX

Download Chilkat .NET for 2.0 / 3.5 Framework

Download Chilkat .NET for 1.0 / 1.1 Framework

Demonstrates how to use a certificate's private key from a PFX file to create an RSA signature.

bool success;

//  Create an instance of a certificate store object, load a PFX file,
//  locate the certificate we need, and use it for signing.
//  (a PFX file may contain more than one certificate.)
Chilkat.CertStore certStore = new Chilkat.CertStore();

//  The 1st argument is the filename, the 2nd arg is the
//  PFX file's password:
success = certStore.LoadPfxFile("chilkat.pfx","test");
if (success != true) {
    MessageBox.Show(certStore.LastErrorText);
    return;
}

Chilkat.Cert cert = null;
cert = certStore.FindCertBySubject("Chilkat Software, Inc.");
if (cert == null ) {
    MessageBox.Show(certStore.LastErrorText);
    return;
}

Chilkat.PrivateKey pkey = null;
pkey = cert.ExportPrivateKey();
if (pkey == null ) {
    MessageBox.Show(cert.LastErrorText);
    return;
}

string pkeyXml;
//  Get the private key in XML format:
pkeyXml = pkey.GetXml();

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

//  Any string argument automatically begins the 30-day trial.

success = rsa.UnlockComponent("30-day trial");
if (success != true) {
    MessageBox.Show("RSA component unlock failed");
    return;
}

//  Import the private key into the RSA component:
success = rsa.ImportPrivateKey(pkeyXml);
if (success != true) {
    MessageBox.Show(rsa.LastErrorText);
    return;
}

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

textBox1.Text += hexSig + "\r\n";
textBox1.Refresh();

MessageBox.Show("Success!");