*04:17*[Pub][JoC] Fully Leakage-Resilient Signatures

Abstract A signature scheme is *fully leakage resilient* (Katz and Vaikuntanathan, ASIACRYPT’09) if it is existentially unforgeable under an adaptive chosen-message attack even in a setting where an adversary may obtain bounded (yet arbitrary) leakage information on *all intermediate values that are used throughout the lifetime of the system*. This is a strong and meaningful notion of security that captures a wide range of side-channel attacks. One of the main challenges in constructing fully leakage-resilient signature schemes is dealing with leakage that may depend on the random bits used by the signing algorithm, and constructions of such schemes are known only in the random-oracle model. Moreover, even in the random-oracle model, known schemes are only resilient to leakage of less than half the length of their signing key. In this paper we construct the first *fully* leakage-resilient signature schemes without random oracles. We present a scheme that is resilient to any leakage of length (1−*o*(1))*L* bits, where *L* is the length of the signing key. Our approach relies on generic cryptographic primitives, and at the same time admits rather efficient instantiations based on specific number-theoretic assumptions. In addition, we show that our approach extends to the continual-leakage model, recently introduced by Dodis, Haralambiev, Lopez-Alt and Wichs (FOCS’10), and by Brakerski, Tauman Kalai, Katz and Vaikuntanathan (FOCS’10). In this model the signing key is allowed to be refreshed, while its corresponding verification key remains fixed, and the amount of leakage is assumed to be bounded only in between any two successive key refreshes.

- Content Type Journal Article
- Pages 1-46
- DOI 10.1007/s00145-012-9136-3
- Authors
- Elette Boyle, Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Gil Segev, Microsoft Research, Mountain View, CA 94043, USA
- Daniel Wichs, Department of Computer Science, New York University, New York, NY 10012, USA

- Journal Journal of Cryptology
- Online ISSN 1432-1378
- Print ISSN 0933-2790