Self-certified proxy convertible authenticated encryption: formal definitions and a provably secure scheme

摘要

In 2009, Wu and Lin introduced the concept of self-certified proxy convertible authenticated encryptionrn(SP-CAE) by integrating self-certified public-key system and designated verifier proxy signature withrnmessage recovery. They also presented the first SP-CAE scheme which is based the discrete logarithmrnproblem. However, Wu-Lin scheme is not secure as Xie et al. recently showed that this scheme is existentiallyrnforgeable under adaptive chosen warrants, unconfidentiable and verifiable under adaptive chosenrnmessages and designated verifiers. In this paper, we first discuss the security requirements of SP-CAErnand then formally define unforgeability, message confidentiality, and unverifiability. Consequently, thernfirst complete formal model of SP-CAE is proposed. After that, we propose a provably secure SP-CAErnscheme by using two-party Schnorr signature introduced by Nicolosi et al. in 2003. Finally, we prove thernformal security of the proposed scheme in the random oracle model under the discrete logarithmrnassumption.