Multidivisible Online/Offline Cryptography and Its Application to Signcryptions

Abstract

We introduce a general concept of multidivisible online/offline (MDO) cryptography, which covers the previous works including online/offline cryptographic schemes, divisible online/offline signatures, incrementally executable signcryptions, and multidivisible online/offline encryptions. We then present the notion of multidivisible online/offline signcryptions (MDOSCs) as novel application of MDO cryptography. We define several security notions for MDOSCs and show implications and separations between these security notions. We also present a generic construction of MDOSC that achieves the strongest security notions with regard to confidentiality and unforgeability. Using MDOSC schemes, the computationally restricted and/or bandwidth-restricted devices can transmit messages in both confidential and authenticated way with low computational overhead and/or low-bandwidth network.