Cryptology ePrint Archive: Report 2015/683

Security of Linear Secret-Sharing Schemes against Mass Surveillance

Irene Giacomelli and Ruxandra F. Olimid and Samuel Ranellucci

Abstract: Following the line of work presented recently by Bellare, Paterson and Rogaway, we formalize and investigate the resistance of linear secret-sharing schemes to mass surveillance. This primitive is widely used to design IT systems in the modern computer world, and often it is implemented by a proprietary code that the provider (“big brother”) could manipulate to covertly violate the privacy of the users (by implementing Algorithm-Substitution Attacks or ASAs). First, we formalize the security notion that expresses the goal of big brother and prove that for any linear secret-sharing scheme there exists an undetectable subversion of it that efficiently allows surveillance. Second, we formalize the security notion that assures that a sharing scheme is secure against ASAs and construct the first sharing scheme that meets this notion. This work could serve as an important building block towards constructing systems secure against mass surveillance.

Category / Keywords: linear secret-sharing, algorithm-substitution attack, mass surveillance, kleptography

Original Publication (with minor differences): CANS 2015 proceedings

Date: received 7 Jul 2015, last revised 18 Sep 2015

Contact author: giacomelli at cs au dk

Available format(s): PDF | BibTeX Citation

Note: Full version of the paper accepted at CANS2015

Version: 20150918:120351 (All versions of this report)

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