Tight lower bounds and optimal constructions of anonymous broadcast encryption and authentication

Abstract Broadcast Encryption (BE) is public-key encryption allowing a sender to encrypt message by specifing recipients, and only the specified recipients can decrypt message. In several BE applications, since privacy of allowed access often as important confidentiality message, anonymity introduced an additional but security requirement for BE. Kiayias Samari (IH 2013) presented asymptotic lower bound on ciphertext sizes in schemes satisfying (ANO-BE short). More precisely, their derived under assumption that ANO-BE have special property. However, it insufficient show asymptotically tight unclear whether existing meet this work, we derive bounds size assuming properties most satisfy. With similar technique, first asymptoticallyPlease provide MSC codes. For more details, please visit http://www.ams.org/msc/. authenticator Anonymous Authentication (ABA). Furthermore, extend above result present (non-asymptotically) upper thePlease check confirm Running title. ANO-BE. We variant scheme proposed Li Gong (ACNS 2018) optimal. also ABA via same approach ANO-BE, propose optimal construction ABA.