Constructions of Secure Multi-Channel Broadcast Encryption Schemes in Public Key Framework

Multi-Channel Broadcast Encryption (MCBE) introduced by Phan et al. provides a suitable way to broadcast messages efficiently to groups of recipients while usual broadcast encryption (BE) sends a message to a particular group of users, consequently increases communication bandwidth and computation cost to send different messages to different group of users by employing BE repeatedly. We have proposed two public key multi-channel broadcast encryption schemes while all the existing schemes are in private key setting. Our first construction achieves semi-static security against chosen plaintext attack (CPA) under Decisional Bilinear Diffie-Hellman Exponent Sum (DBDHE-sum) assumption and second scheme achieves selective security against CPA under modified squared Decisional Diffie-Hellman Exponent (m-sq-DDHE) assumption. Both of our proposed constructions have constant header size. Our second construction achieves outsider-anonymity which hides user identity from outsiders apart from data hiding.