Unconditionally secure cryptographic protocols from coding-theoretic primitives

Spini, G. (2017)

Doctoral Thesis

This dissertation presents new cryptographic protocols, which can be divided into two families. Protocols in the first family achieve unilateral security: this means that they protect legitimate users against an external attacker. Concretely, we assume that two users wish to communicate securely over a given communication system, where an external attacker eavesdrops and tampers with some of the wires of the system. We contribute to the topic by presenting protocols with improved efficiency and a simpler definition compared to previous work, and we design interactive protocols that achieve security against a stronger attacker.

Protocols of the second type achieve multilateral security, meaning that they protect users against each other. This is the case for multi-party computation or MPC, where several users wish to compute a function on private inputs while keeping inputs private and without appealing to a trusted third party; we contribute to this topic by adding a cheater-detection functionality to a well-established MPC protocol.

A key component that underlies these scenarios is secret sharing; we investigate this topic by casting in particular a new light on its connections with coding theory. This allows us to better harness the features of recent code constructions to obtain improved secret-sharing schemes.

• Cryptography
• Information Theoretic Security
• Coding Theory
• Secret Sharing
• Perfectly Secure Message Transmission
• Secure Network Coding
• Multiparty Computation

• All authors: Spini, G.
• Supervisor: Cramer, R.; Zémor, G.
• Co-supervisor: Fehr, S.
• Committee: Ishai, Y.; Orsini, E.; Schoenmakers, B.; Smit, B. de; Vaart, A. van der
• Qualification: Doctor (dr.)
• Awarding Institution: Mathematisch Instituut, Science, Leiden University
• Date: 2017-12-06
• Sponsorship: Algant-Doc