class GPGME::Ctx

def verify(sig, signed_text = nil, plain = Data.new)

Verify that the signature in the data object is a valid signature. 
def verify(sig, signed_text = nil, plain = Data.new)
  err = GPGME::gpgme_op_verify(self, sig, signed_text, plain)
  exc = GPGME::error_to_exception(err)
  raise exc if exc
  plain
end