Efficient Broadcast Encryption with Personalized Messages

BPRT: A blockchain‐based privacy‐preserving transaction scheme based on an efficient broadcast encryption with personalized messages

“…In BE schemes, a broadcaster sends a common message $$$ m $$$ encrypted by a session key $$$ K $$$ to a set of users in $$$ S $$$, and users outside $$$ S $$$ have no access to correctly decrypt the ciphertext for obtaining $$$ K $$$. Ohtake et al 14 introduced the concept of BE with personalized messages (BEPM). It is different from BE that broadcaster can send both common message and personalized messages to target users, which is audit friendly.…”

“…We have noticed that prior works of BEPM do not consider the issue of anonymity except schemes in References 15 and 16. It is inconvenient in practice to apply current BEs with personalized messages such as those in References 14,16‐20 for the reason that the target user has to know who else is able to correctly decrypt the ciphertext, which also leads to a severe privacy leakage of target receiver in the blockchain. Schemes in References 15 and 16 only achieve outsider anonymity that is weaker than full anonymity for the reason that information of receiver's identities are exposed to all target receivers in outsider anonymous BEPM scheme.…”

“…Kurosawa 38 proposed a multirecipient encryption that can send personalized messages to different recipients with shortened ciphertext compared with the trivial scheme, but it cannot send common message. Ohtake et al 14 proposed the first BE with personalized messages that owns advantages on Conditional Access System. This scheme is based on the public key infrastructure, and it only achieves security against chosen plaintext attack (CPA).…”

“…This scheme is based on the public key infrastructure, and it only achieves security against chosen plaintext attack (CPA). Fujii et al 39 put forward a BEPM of which the computation and storage cost are the same as Reference 14. However, Han et al 17 pointed out that the inputs of BEPM's decryption algorithm in Reference 39 should include some portion of public key that is essential for decryption.…”

“…Constructions of the first scheme and the second scheme are similar with Reference 14. The third scheme achieves logarithmic size public parameter based on multilinear maps, while the size of public parameter in References 14,17,39 are linear to the size of target user set. However, all of these schemes are not anonymous.…”