Multi-recipient signcryption for secure group communication

When a sender sends multiple messages to multiple recipients, overheads can be reduced efficiently by multi-recipient signcryption schemes. We proposed two multi-recipient signcryption schemes. The first scheme called SM-MR SCS (Single Message - Multiple Receivers SignCryption Scheme), which is an efficient broadcast signcryption scheme. The second scheme called MM-MR SCS (Multiple Messages - Multiple Receivers SignCryption Scheme) can send the distinct message to different recipients simultaneously. The proposed schemes keep the same security level as SCS due to its reproducibility. Compared with traditional methods, overheads of the new schemes are reduced sharply. They are more efficient than other known schemes when a sender sends different messages to distinct recipients.