This method verifies digitally signed data
0 if the verifying process was completed successfully.
one of the following error codes otherwise,
Use this method to
verify the detached digital signature for a message.
Signature should be contained in PKCS7-compatible format.
Message is validated using certificates which it contains. If message does not contain the appropriate certificate, certificates from CertStorage are used.
Check Certificates property after calling this method to get certificates which are included in message.