Sign a File to Create a .p7s File (Detached Signature)

C# example to create a detached signature file (.p7s) for any type file. The signature can be verified by calling VerifyP7S and passing the original filename and the .p7s filename.

Download Chilkat .NET for 2.0 Framework

Download Chilkat .NET for 1.0 / 1.1 Framework

Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

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

//  Find our digital certificate from the Current User certificate store.
Chilkat.CreateCS ccs = new Chilkat.CreateCS();
Chilkat.CertStore certStore;
certStore = ccs.OpenCurrentUserStore();
Chilkat.Cert cert;
cert = certStore.FindCertBySubjectCN("Chilkat Software, Inc.");
if (cert == null ) {
    MessageBox.Show(cert.LastErrorText);

    return;
}

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

//  We can sign any type of file, creating a .p7s as output:
success = crypt.CreateP7S("license.rtf","license.p7s");
if (success == false) {
    MessageBox.Show(crypt.LastErrorText);

    return;
}

//  Verify the signature:
crypt.SetVerifyCert(cert);

success = crypt.VerifyP7S("license.rtf","license.p7s");
if (success == false) {
    MessageBox.Show(crypt.LastErrorText);

    return;
}

MessageBox.Show("Success!");