(C# UWP/WinRT) Sign a Byte Array to Create an Opaque Signature in a Byte Array

Signs data contained in a byte array to produce an opaque signature (also in a byte array). An opaque signature is a PKCS7 signature (also known as CAdES) that embeds the signed data. Also shows how to verify the signature and extract the original data.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

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

Chilkat.Cert cert = new Chilkat.Cert();
bool success = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

Chilkat.FileAccess fac = new Chilkat.FileAccess();

byte[] fileBytes = null;
fileBytes = fac.ReadEntireFile("qa_data/pdf/sample.pdf");
if (fac.LastMethodSuccess != true) {
    Debug.WriteLine(fac.LastErrorText);
    return;
}

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

success = crypt.SetSigningCert(cert);

// We can sign any type of file.

byte[] sigBytes = null;
sigBytes = await crypt.OpaqueSignBytesAsync(fileBytes);
if (crypt.LastMethodSuccess != true) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

success = fac.WriteEntireFile("qa_output/sample.pdf.p7m",sigBytes);
if (fac.LastMethodSuccess != true) {
    Debug.WriteLine(fac.LastErrorText);
    return;
}

// We can verify the opaque signature and extract the original data like this
byte[] originalData = null;
originalData = crypt.OpaqueVerifyBytes(sigBytes);
if (crypt.LastMethodSuccess != true) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

success = fac.WriteEntireFile("qa_output/sample.pdf",originalData);
if (fac.LastMethodSuccess != true) {
    Debug.WriteLine(fac.LastErrorText);
    return;
}

Debug.WriteLine("Signature is verified and the original data was extracted.");