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Cryptosystem for Post-Quantum Age Based on Moderate-Density Parity-Check (MDPC) Codes
(Tartu Ülikool, 2020) Punnar, Markus; Skachek, Vitaly, juhendaja; Bocharova, Irina, juhendaja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Arvutiteaduse instituut
With the technology for quantum computers being actively developed by researchers worldwide, new methods for encrypting of sensitive data are needed. As a consequence of invention of Shor’s algorithm, all cryptographic schemes based on finding the prime factors will become insecure, which include various asymmetric cryptosystems used today. The McEliece cryptosystem is based on the difficulty to distinguish structured linear codes from random linear codes. As it is believed to be immune to known attacks possible with a quantum computer, the McEliece cryptosystem is one of the main candidates for ensuring the confidentiality of sensitive data in a post-quantum environment. However, the construction of McEliece suffers from a large key size which makes using the scheme inefficient. There have been numerous variations to the original construction of the McEliece cryptosystem, but most of them have been proven to be insecure. One of the best candidates is the McEliece cryptosystem variation based on moderate density parity-check codes and its quasi-cyclic variant, which has not been successfully attacked while reducing the key size drastically. In this work, an overview of both the original construction of the McEliece cryptosystem and its modern variant is given, and iterative decoding algorithms used in decrypting messages in the cryptosystem are presented and analyzed.
Experimental Integration of the Smart-ID Service Into Intel SGX Enclaves
(Tartu Ülikool, 2023) Punnar, Markus; Laud, Peeter, juhendaja; Kisand, Armin Daniel, juhendaja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Arvutiteaduse instituut
Privacy-preserving services are becoming increasingly important as they allow untrusted remote servers to process sensitive information while preserving the privacy of that information. To ensure the security and privacy of such services, strong authentication mechanisms based on public-key cryptography are required instead of password-based authentication. While there are several standardized authentication services available, such as Smart-ID and mobile-ID, they are not yet integrated with Sharemind HI, a development platform for privacy-preserving services. This thesis aims to address this gap by developing a proof-of-concept service that runs in a trusted execution environment and authenticates users using the Smart-ID service provider. By leveraging the existing public-key infrastructure, the proposed service would allow for the development of privacy-preserving applications on a national scale where sensitive data remains secure from remote untrusted servers and administrators. To achieve this goal, the prototype was developed on the Sharemind HI platform, which simplifies the development of privacy-preserving applications and is based on the Intel SGX platform. The prototype demonstrates the feasibility of securely communicating with the Smart-ID service provider from a trusted execution environment and integrating Smart-ID authentication into the Sharemind HI platform. However, further work is required to optimize the prototype in terms of time and space and to develop a scalable solution for integrating external authentication providers without adding unnecessary complexity to the core modules.