Birthday paradox based security analysis of certain broadcast encryption schemes

Abstract

This letter yields a security evaluation of certain broadcast encryption (BE) schemes regarding the generic vulnerability of the textbook BE schemes. The considered vulnerability can be effectively explored assuming known plaintext attacks which in a realistic scenario, corresponding to a legitimate user being the attacker, appears as a ciphertext only attack. Employing the birthday paradox, a dedicated time-data tradeoff based algorithm for cryptanalysis is proposed. The developed algorithm is applied to cryptanalysis of particular recently reported class of BE schemes, implying additional insights regarding motivations for their security improvements.