The idea of the present invention is to replace the existing password/user ID based authentication process by a new digital signature authentication process in which preferably the first HTTP-requestheader is extended by the client authentication information independently of the authentication process used by the destination server and without server requesting authentication information. The authentication information preferably includes the client certificate containing the client public key, signed by certification authority, and preferably a hash value calculated over the HTTP-request header data being sent in the request, and encrypted with the Client's private key. The certificate and digital signature may be added during the creation of the HTTP-request header in the client systemitself, or may be added later in a server acting as a gateway, proxy, or tunnel. A destination server that does not support the new digital signature authentication process will simply ignore the certificate and digital signature in the HTTP-request header and will automatically initiate its own authentication process. The present invention simplifies the existing digital signature authenticationprocess and concurrently allows the coexistence of different authentication processes without changing the HTTP-protocol or causing unnecessary network traffic.