Cryptology ePrint Archive: Report 2017/354

Tightly Secure Ring-LWE Based Key Encapsulation with Short Ciphertexts

Martin R. Albrecht and Emmanuela Orsini and Kenneth G. Paterson and Guy Peer and Nigel P. Smart

Abstract: We provide a tight security proof for an IND-CCA Ring-LWE based Key Encapsulation Mechanism that is derived from a generic construction of Dent (IMA Cryptography and Coding, 2003). Such a tight reduction is not known for the generic construction. The resulting scheme has shorter ciphertexts than can be achieved with other generic constructions of Dent or by using the well-known Fujisaki-Okamoto constructions (PKC 1999, Crypto 1999). Our tight security proof is obtained by reducing to the security of the underlying Ring-LWE problem, avoiding an intermediate reduction to a CPA-secure encryption scheme. The proof technique maybe of interest for other schemes based on LWE and Ring-LWE.

Category / Keywords: public-key cryptography /

Original Publication (with minor differences): ESORICS 2017

Date: received 20 Apr 2017, last revised 27 Jun 2017

Contact author: Kenny Paterson at rhul ac uk,Martin Albrecht@rhul ac uk,nigel@cs bris ac uk,Emmanuela Orsini@bristol ac uk,guy peer@dyadicsec com

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Version: 20170627:090431 (All versions of this report)

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