Abstract: End-to-end security between clients and a server, and traffic visibility to intermediate network devices, achieved through combined mode, single pass encryption and authentication using two keys is disclosed. In various embodiments, a combined encryption-authentication unit includes a cipher unit and an authentication unit coupled in parallel to the cipher unit, and generates an authentication tag using an authentication key in parallel with the generation of the cipher text using an encryption key, where the authentication and encryption key have different key values.