Authentication Systems

This document discusses various topics related to authentication including passwords, address based authentication, key distribution centers (KDCs), certification authorities (CAs), multiple trust domains, and session keys. It covers how passwords should be securely stored and transmitted. It also explains address based authentication using files like hosts.equiv and per-user .rhosts files and their security issues. The document discusses using KDCs or CAs to distribute secret keys between systems in a network and handling multiple trust domains between KDCs or CAs. It recommends establishing new session keys for each communication session for security.