(Mono C#) Duplicate OpensSSL to Sign File and Output Binary DER

This example duplicates the following:

openssl smime -sign -in INPUT.xml -signer SIGN.PEM -passin pass:MYPASS -outform der -binary -nodetach -out SIGNED.P7M

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 PEM containing cert + private key.
Chilkat.Pem pem = new Chilkat.Pem();
bool success = pem.LoadPemFile("qa_data/pem/myPem.pem","password");
if (success != true) {
    Debug.WriteLine(pem.LastErrorText);
    return;
}

Chilkat.PrivateKey privkey = pem.GetPrivateKey(0);
if (pem.LastMethodSuccess != true) {
    Debug.WriteLine(pem.LastErrorText);
    return;
}

Chilkat.Cert cert = pem.GetCert(0);
if (pem.LastMethodSuccess != true) {

    Debug.WriteLine(pem.LastErrorText);
    return;
}

success = crypt.SetSigningCert2(cert,privkey);
if (success != true) {

    Debug.WriteLine(crypt.LastErrorText);
    return;
}

// Alternatively, we could use a .pfx/.p12 file.
// (Chilkat also supports other formats/sources for cert/private keys...)
Chilkat.Cert certFromP12 = new Chilkat.Cert();
success = certFromP12.LoadPfxFile("qa_data/p12/myP12.p12","password");
if (success != true) {
    Debug.WriteLine(certFromP12.LastErrorText);
    return;
}

// The certificate, when loaded from a .pfx/.p12, will automatically 
// include the associated private key, assuming it's present in the .p12.
// We don't have to explicitly provide the private key as in the
// lines of code above that use the PEM file.
success = crypt.SetSigningCert(certFromP12);
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.p7m");
if (success != true) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

Debug.WriteLine("Success.");