Paper 2019/1439

Cryptanalysis of a pairing-free certificate-based proxy re-encryption scheme for secure data sharing in public clouds

S. Sharmila Deva Selvi and Irene Miriam Isaac and C. Pandu Rangan

Abstract

Proxy re-encryption(PRE) is a primitive that is used to facilitate secure access delegation in the cloud. Proxy re-encryption allows a proxy server to transform ciphertexts encrypted under one user's public key to that under another user's public key without learning anything about the underlying message or the secret key. Over the years proxy re-encryption schemes have been proposed in different settings. In this paper we restrict our analysis to certificate based proxy re-encryption. The first CCA secure certificate based PRE without bilinear pairings was proposed by Lu and Li in Future Generation Computer Systems, 2016. In this paper we present a concrete attack on their scheme and prove that it is not CCA secure.