Strong Post-Compromise Secure Proxy Re-Encryption

Alex Davidson, Amit Deo, Ela Lee, Keith Martin

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Proxy Re-Encryption (PRE) allows a ciphertext encrypted using a key to be re-encrypted by a third party so that it is an encryption of the same message under a new key, without revealing the message. We define Post-Compromise Security (PCS) in the context of PRE. This ensures that an adversary cannot distinguish which of two adversarially chosen ciphertexts a re-encryption was created from even when given the old secret key and the update token used to perform the re-encryption. We give separating examples demonstrating how PCS is stronger than existing security definitions for PRE achieving similar goals, before showing that PCS can be achieved using a combination of existing security properties from the literature. In doing so, we show there are existing PRE schemes satisfying PCS. Finally, we give a construction demonstrating that natural modifications of practical PRE schemes provably have PCS directly, without incurring overheads from the security reductions we have shown, and from weaker assumptions than existing schemes.

Original languageEnglish
Title of host publicationInformation Security and Privacy - 24th Australasian Conference, ACISP 2019, Proceedings
EditorsJulian Jang-Jaccard, Fuchun Guo
Number of pages20
ISBN (Electronic)978-3-030-21548-4
ISBN (Print)978-3-030-21547-7
Publication statusE-pub ahead of print - 30 May 2019
Event24th Australasian Conference on Information Security and Privacy, ACISP 2019 - Christchurch, New Zealand
Duration: 3 Jul 20195 Jul 2019

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume11547 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference24th Australasian Conference on Information Security and Privacy, ACISP 2019
Country/TerritoryNew Zealand

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