(.NET Core C#) Extract XML string from a .p7m byte array (e.g. FATTURA ELETTRONICA, ITALY)

.NET Core C# example to extract the original XML from a .p7m (Signed-Data PKCS7 Format) provided as a byte array.

One use for this example is to extract the original XML from a Fattura Elettronica .p7m signature.

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.FileAccess fac = new Chilkat.FileAccess();
byte[] p7mBytes = null;
p7mBytes = fac.ReadEntireFile("testData/p7m/fattura_signature.p7m");
if (fac.LastMethodSuccess != true) {
    Debug.WriteLine(fac.LastErrorText);
    return;
}

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

string originalXml = crypt.OpaqueVerifyString(p7mBytes);
if (crypt.LastMethodSuccess != true) {
    Debug.WriteLine(fac.LastErrorText);
    return;
}

Debug.WriteLine("Original XML:");
Debug.WriteLine(originalXml);

Debug.WriteLine("Success!");