Security of Linear Secret-Sharing Schemes Against Mass Surveillance

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.

• Type: Journal
• Year: 2015
• Where: CANS
• Authors: Irene Giacomelli, Ruxandra F. Olimid, Samuel Ranellucci
• Keywords: CANS 2015, Cryptology