Non-transferability in Proxy Re-Encryption Revisited

Arinjita Paul¹⁺, Lihua Wang², S. Sharmila Deva Selvi¹, and C. Pandu Rangan¹

¹Department of Computer Science and Engineering, IIT Madras, Chennai, India
{arinjita, sharmila, prangan}@cse.iitm.ac.in

²National Institute of Information and Communications Technology (NICT), Tokyo, Japan

lh-wang@nict.go.jp

Abstract

Proxy re-encryption (PRE) is a cryptographic primitive envisioned by Blaze, Bleumer and Strauss to realise delegation of decryption rights from a delegator to a delegatee via a semi-trusted proxy. The widely accepted model for PRE security prevents the proxy, which is equipped with transformation power, to learn anything about the underlying plaintext. However, such a security notion is not sufficient in practical scenarios wherein the proxy could be corrupted. In this work, we study an attractive property of PRE, namely non-transferability that prevents the colluding proxy and the delegatee from re-delegating decryption rights to a malicious user. In Pairing 2010, a CPA secure non-transferable identity-based PRE scheme was presented in the random oracle model. In this work, we show that the scheme does not realize non-transferability. Also, we formalize the notion of a non-transferable PRE and introduce a security definition for the same. We then present the first provably secure construction of a non-transferable PRE scheme in the PKI setting based on bilinear maps. Our scheme meets chosen ciphertext security and non-transferability in the random oracle model assuming a variant of the decisional bilinear Diffie-Hellman problem.

Keywords: Proxy Re-Encryption, Non-transferability, Unidirectional, CCA-secure, Random Oracle,

Bilinear Pairing

+: Corresponding author: Arinjita Paul
Department of Computer Science and Engineering, IIT Madras, Chennai-600036, India,
Tel: +91-44-2257-5387

Journal of Internet Services and Information Security (JISIS), 10(3): 1-30, August 2020

DOI: 10.22667/JISIS.2020.08.31.001 [pdf]