(C#) 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 .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

// 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 = crypt.OpaqueSignBytes(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.");