A single key pair is adequate for the Zheng signcryption. (English)
Parampalli, Udaya (ed.) et al., Information security and privacy. 16th Australasian conference, ACISP 2011, Melbourne, Australia, July 11‒13, 2011. Proceedings. Berlin: Springer (ISBN 978-3-642-22496-6/pbk). Lecture Notes in Computer Science 6812, 371-388 (2011).
Summary: We prove that the original Zheng signcryption scheme published at Crypto’97, with a couple of minor tweaks, requires only a single public/private key pair for each user. That is the user can employ the same public/private key pair for both signcryption and unsigncryption in a provably secure manner. We also prove that the Zheng signcryption scheme allows a user to securely signcrypt a message to himself. Our first result confirms a long-held belief that signcryption reduces the overhead associated with public keys, while our second result foretells potential applications in cloud storage where one with a relatively less resourceful storage device may wish to off-load data to an untrusted remote storage network in a secure and unforgeable way.