Use Certificate and Private Key PEM Files to Create a Digital Signature

Demonstrates how to load a digital certificate from a PEM file, load it's corresponding private key from a PEM file, save the private key to a key container (if necessary), link the certificate to the key container, and use it to create a digital signature.

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Chilkat.Cert cert = new Chilkat.Cert();

//  Load the cert from a PEM file;
cert.LoadFromFile("cert.pem");

Chilkat.PrivateKey pkey = new Chilkat.PrivateKey();

//  Load the private key from an RSA PEM file:
pkey.LoadPemFile("pkey_rsa.pem");

bool success;

success = cert.SetPrivateKey(pkey);
if (success != true) {
    textBox1.Text += cert.LastErrorText + "\r\n";
    return;
}

//  Use Chilkat Crypt (a non-freeware component) to create
//  a digital signature using the certificate w/ private key:
Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

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

success = crypt.UnlockComponent("30-day trial");
if (success != true) {
    textBox1.Text += crypt.LastErrorText + "\r\n";
    return;
}

//  Tell the crypt component to use this cert.
crypt.SetSigningCert(cert);

//  A PKCS7 signature for any type of file content can be created:
success = crypt.CreateP7S("license.rtf","license.p7s");
if (success == false) {
    textBox1.Text += crypt.LastErrorText + "\r\n";
    return;
}

textBox1.Text += crypt.LastErrorText + "\r\n";

//  Verify and restore the original file:
crypt.SetVerifyCert(cert);

success = crypt.VerifyP7S("license.rtf","license.p7s");
if (success == false) {
    textBox1.Text += crypt.LastErrorText + "\r\n";
    return;
}

MessageBox.Show("Success!");