Abstract. Multi-receiver authentication is an extension of traditional point-to-point message authentication in which a sender broadcasts a single authenticated message such that all the receivers can independently verify the authenticity of the message, and malicious groups of up to a given size of receivers can not successfully impersonate the transmitter, or substitute a transmitted message. This paper presents some new resalts on unconditionally secure multi-receiver authentication codes. First we generalize a polynomial construction due to Desmedt, Frankel and Yung, to allow multiple messages be authenticated with each key. Second, we propose a new flexible construction for multi-receiver A-code by combining an A-code and an (n, m, k)-cover-free family. Finally, we introduce the model of malti-receiver A-code with dynamic sender and present an efficient construction for that.Keywords: Authentication code, Multi-receiver authentication code.
IntroductionConventional authentication systems deal with point-to-point message authentication. In Simmons' model of unconditionally secure authentication there are three participants: a transmitter (sender), a receiver, and an opponent. The transmitter and the receiver share a secret key and are both assumed honest. The message is sent over a public channel which is subject to active attack. Transmitter and receiver use an authentication code which is a set of authentication functions f, indexed by keys belonging to a set E. To authenticate a message, called a source state and denoted by s E S, transmitter forms a codeword f (e, s) and sends it to the receiver who can verify its authenticity using his knowledge of the key. We are only concerned with sys$ernatic Cartesian A-codes in which the codeword constructed for s using e E E is the concatenation of s and f(e, denotes the set of all tags.