An Efficient Identity-Based Signcryption Scheme for Multiple Receivers

This paper puts forward a new efficient, construction for Multi-Receiver Signcrypton in the Identify-based setting. We consider a scenario where a user wants to securely send a message to a dynamically changing subset of the receivers in such a way that, non-members of this subset cannot learn the message One obvious solution is to signcrypt the message to each member of the subset and transmit it to each of them m-individually This requires a very long transmission (the number of receivers times the length of the message) and high computation cost. Another simple solution is to provide it key for every possible subset of receivers This requires every user to store a huge number of keys In this case,the storage efficiency is compromised. The goal of this paper is to provide a solution which is efficient, in all three measures i.e. transmission length, storage of keys and computation at both ends. We propose a new scheme that achieves both confidentiality and anthenticity simultaneously in this setting and is the most efficient scheme to date, in the parameters described above. It breaks the barrier of eiphertext length of linear order in the number of receivers and achieves constant sized eiphertext, independent of the size of the receiver