Simple Authentication Schemes for the ALC and NORM Protocols

Overview & Synopsis

This document introduces two schemes that provide a per-packet authentication and integrity service in the context of the ALC and NORM protocols. The first scheme is based on digital signatures. Because it relies on asymmetric cryptography, this scheme generates a high processing load at the sender and to a lesser extent at a receiver, as well as a significanttransmission overhead. It is therefore well suited to low data rate sessions. The second scheme relies on a group message Authentication Code (MAC). Because this scheme relies symmetric cryptography, MAC calculation and verification are fast operations, which makes it suited to high data rate sessions. However it only provides a group authentication and integrity service, which means that it only protects against attackers that are not group members.