Abstract: Various embodiments of systems and methods for re-authentication in client-server communications are described herein. A composite key is constructed by cryptographic hashing of a master key and a user key. A payload is constructed using a user identifier and a validity parameter. The payload is then encrypted using the composite key. A token is constructed by combining the encrypted payload, the user identifier, and a master key identifier. The constructed token is transmitted to the client system. To establish a subsequent session, the token is received at the server from the client system for re-authentication. The server validates the received token and establishes the subsequent session if the token is validated.