Towards secure communication and authentication: Provable security analysis and new constructions

Abstract

Secure communication and authentication are some of the most important and practical topics studied in modern cryptography. Plenty of cryptographic protocols have been proposed to accommodate all sorts of requirements in different settings and some of those have been widely deployed and utilized in our daily lives. It is a crucial goal to provide formal security guarantees for such protocols. In this thesis, we apply the provable security approach, a standard method used in cryptography to formally analyze the security of cryptographic protocols, to three problems related to secure communication and authentication. First, we focus on the case where a user and a server share a secret and try to authenticate each other and establish a session key for secure communication, for which we propose the first user authentication and key exchange protocols that can tolerate strong corruptions on the client-side. Next, we consider the setting where a public-key infrastructure (PKI) is available and propose models to thoroughly compare the security and availability properties of the most important low-latency secure channel establishment protocols. Finally, we perform the first provable security analysis of the new FIDO2 protocols, the promising proposed standard for passwordless user authentication from the Fast IDentity Online (FIDO) Alliance to replace the world's over-reliance on passwords to authenticate users, and design new constructions to achieve stronger security.