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

Download: Chilkat .NET Assemblies

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.

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 = null;
certStore = ccs.OpenCurrentUserStore();
Chilkat.Cert cert = null;
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!");