Modern life is based on different e-commerce applications for on-line booking tickets, electronic transactions, shopping etc. Smart cards are playing an essential role in many e-commerce applications due to low cost, portability. Remote users can get the benefit of different services using a single smart card in multi-server communication environment. However, this type of system has a major security drawback as the user always shows the same identity to different services and the system becomes vulnerable to many attacks. To eliminate the security problem, we introduce a security token service for secure multi-server authentication scheme using a single electronic identity card in a communication network. For further security, we use Diffie–Hellman DSA key exchange for message protection. Diffie–Hellman is a popular key exchange technique which produces secret key for symmetric encryption for efficient and secure e-commerce transaction.