(Mono C#) Duplicate OpensSSL to Create Signature using Cert and Key Files

This example duplicates the following:

openssl smime –sign -in something.xml -out something.der -signer mycert.crt -inkey cert.key -outform der –nodetach

Note: Although "smime" is the OpenSSL command, it's not actually producing S/MIME. The arguments "-outform der -binary" indicates that the output is binary DER (i.e. the PKCS7 binary signature). The input can be any type of file: XML, PDF, JPG, ... *anything*...

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

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

// Load the cert and private key from separate files.
Chilkat.Cert cert = new Chilkat.Cert();
bool success = cert.LoadFromFile("myCert.crt");
if (success != true) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

Chilkat.BinData bd = new Chilkat.BinData();
success = bd.LoadFile("cert.key");
Chilkat.PrivateKey privkey = new Chilkat.PrivateKey();
// Load from any format private key.
// If the file does not need a password, the 2nd arg is ignored.
success = privkey.LoadAnyFormat(bd,"password_if_needed");
if (success != true) {
    Debug.WriteLine(privkey.LastErrorText);
    return;
}

success = crypt.SetSigningCert2(cert,privkey);
if (success != true) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

// Create the opaque signature (PKCS7 binary DER that contains both the signature and original file data).
success = crypt.CreateP7M("qa_data/infile.anything","qa_output/outfile.der");
if (success != true) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

Debug.WriteLine("Success.");