Paper 2008/253 Original: eprint.iacr.org/2008/253 ↗

Multi-Recipient Signcryption for Secure Wireless Group Communication

Abstract

Secure group communication is significant for wireless and mobile computing. Overheads can be reduced efficiently when a sender sends multiple messages to multiple recipients using multi-recipient signcryption schemes. In this paper, we proposed the formal definition and security model of multi-recipient signcryption, presented the definition of reproducible signcryption and proposed security theorems for randomness reusing based multi-recipient signcryption schemes. We found that a secure reproducible signcryption scheme can be used to construct an efficient multi-recipient signcryption scheme which has the same security level as the underlying base signcryption scheme. We constructed a multi-recipient scheme which is provable secure in random oracle model assuming that the GDH problem is hard, based on a new BLS-type signcryption scheme. Overheads of the new scheme are only (n+1)/2n times of traditional ways when a sender sends different messages to n distinct recipients. It is more efficient than other known schemes. It creates a possibility for the practice of the public key cryptosystem in ubiquitous computing.