International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 17 December 2013

Aggelos Kiayias, Qiang Tang
ePrint Report ePrint Report
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.

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