Post-quantum algorithms support in Trusted Execution Environment

With the advent of quantum computing numerous are the benefits and advancements introduced in several fields, but it also poses significant threats to cybersecurity. Current cryptosystems are endangered, given the quantum capabilities that this new technology exploits to perform computation and one of the most critical areas regards the public-key algorithms used, as they are susceptible to attacks due to the existence of Shor's algorithm, which can efficiently factorise large numbers and compute discrete logarithms, security's foundation of these algorithms. Recognizing the need for post-quantum (PQ) security, the National Institute of Standards and Technology (NIST) has issued a Call for Proposals to standardize algorithms that can provide security against both traditional and quantum computers. Furthermore, the confidential computing concept has also made significant advancements in the last years. It is the protection of data in use in a hardware-based Trusted Execution Environment (TEE), in which trusted applications (TAs) are executed securely and isolated. Such TEE heavily relies on the usage of public-key algorithms to compute signatures and perform attestation, achieving the ability to attest that a system has not been subject to unauthorized modifications. This Master's thesis aims to extend TEEs to support PQ public-key algorithms, specifically addressing the limitations posed by constrained devices such as embedded systems. For this purpose, the Device Identifier Composition Engine (DICE) architecture is leveraged, since it allows to establish a strong device identity in devices with limited capabilities in which no special hardware for attestation is typically available. Published by the Trusted Computing Group (TCG), this specification describes how to establish such identity and to attest software. The work begins by analyzing the TEE technology and describing the DICE architecture, focusing on their heavy usage of digital signatures. Then, the impact of PQ technology on public and symmetric-key algorithms, as well as hash functions is discussed, followed by an examination of the underlying mathematical problems over which PQ cryptography is based on, and of the NIST PQ standardization process with the selected submissions. Next, the FALCON algorithm is presented, chosen among the submissions according to its performance, complexity, security, and memory footprint in the RISC-V QEMU virtualized scenario. The implementation was carried out on a DICE-compliant custom version of the Keystone Enclave framework, open-source framework to build customized TEEs, by implementing the FALCON algorithm in the various layers composing the system and applying the necessary modifications to the X.509 custom library to support the correct usage of the FALCON parameters. In particular, the proposed solution allows to achieve protection in the different stages of the secure boot process and Enclaves execution, including the attestation of the system, thanks to the usage of the FALCON PQ algorithm, enabling the deployment of a quantum-safe alternative.