In the first part of this paper two techniques for system authentication via a password are analyzed. The first is a probabilistic protocol for the improvement of the login security mechanism and the second is a zero knowledge model for system authentication. Their major advantages and disadvantages are identified and commented upon. In the second part of the paper, a new protocol is proposed as a combination of the two, which establishes a new approach which is quite effective in the case of system-to-system authentication. This protocol avoids some of the limitations of the previously mentioned two techniques, while at the same time manages to merge several of the advantages of both.