Cryptology ePrint Archive: Report 2013/845

How to Keep a Secret: Leakage Deterring Public-key Cryptography

Aggelos Kiayias and Qiang Tang

Abstract: How is it possible to prevent the sharing of cryptographic functions? This question appears to be fundamentally hard to address since in this setting the owner of the key {\em is} the adversary: she wishes to share a program or device that (potentially only partly) implements her main cryptographic functionality. Given that she possesses the cryptographic key, it is impossible for her to be {\em prevented} from writing code or building a device that uses that key. She may though be {\em deterred} from doing so.

We introduce {\em leakage-deterring} public-key cryptographic primitives to address this problem. Such primitives have the feature of enabling the embedding of owner-specific private data into the owner's public-key so that given access to {\em any} (even partially functional) implementation of the primitive, the recovery of the data can be facilitated. We formalize the notion of leakage-deterring in the context of encryption, signature, and identification and we provide efficient generic constructions that facilitate the recoverability of the hidden data while retaining privacy as long as no sharing takes place.

Category / Keywords: public-key cryptography /

Original Publication (with major differences): ACM CCS 2013

Date: received 13 Dec 2013, last revised 4 Jul 2017

Contact author: qtang84 at gmail com

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Version: 20170704:235548 (All versions of this report)

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