Verifier-based Password-authenticated Key Exchange Research Articles

TBVPAKE: An efficient and provably secure verifier-based PAKE protocol for IoT applications

Password-authenticated key exchange (PAKE) is an important cryptographic primitive by which two parties are allowed to authenticate each other and establish a cryptographically strong key using a low-entropy password over an insecure channel. Therefore, it is suitable for access control and securing communications between low-cost Internet of Things (IoT) devices where sound security mechanism is difficult to be applied. This paper makes a contribution to securing IoT applications by presenting a secure, efficient and easy-to-implement verifier-based PAKE protocol, named as TBVPAKE (short for Two-Basis Verifier-based PAKE). It is secure against the off-line dictionary attack and server compromise attack, and supports the perfect forward secrecy. Under the widely accepted BPR security model, TBVPAKE is formally proved in this paper in the random oracle model by reducing its security to the Computational Diffie–Hellman (CDH) and Simultaneous Diffie–Hellman (SDH) security assumptions. In addition, we compare the new TBVPAKE with some other outstanding verifier-based PAKE protocols by instantiating them over a commonly used elliptic curve group, and the comparative analysis results definitely show that the new TBVPAKE offers better computational efficiency and ease of implementation. Therefore, the new TBVPAKE might be a better choice for securing IoT applications.

AuCPace: Efficient verifier-based PAKE protocol tailored for the IIoT

Increasingly connectivity becomes integrated in products and devices that previously operated in a stand-alone setting. This observation holds for many consumer applications in the so-called "Internet of Things" (IoT) as well as for corresponding industry applications (IIoT), such as industrial process sensors. Often the only practicable means for authentication of human users is a password. The security of password-based authentication schemes frequently forms the weakest point of the security infrastructure. In this paper we first explain why a tailored protocol designed for the IIoT use case is considered necessary. The differences between IIoT and the conventional Internet use-cases result in largely modified threats and require special procedures for allowing both, convenient and secure use in the highly constrained industrial setting. Specifically the use of a verifier-based password-authenticated key-exchange (V-PAKE) protocol as a hedge against public-key-infrastructure (PKI) failures is considered important. Availability concerns for the case of failures of (part of) the communication infrastructure makes local storage of access credentials mandatory. The larger threat of physical attacks makes it important to use memory-hard password hashing. This paper presents a corresponding tailored protocol, AuCPace, together with a security proof within the Universal Composability (UC) framework considering fully adaptive adversaries. We also introduce a new security notion of partially augmented PAKE that provides specific performance advantages and makes them suitable for a larger set of IIoT applications. We also present an actual instantiation of our protocol, AuCPace25519, and present performance results on ARM Cortex-M0 and Cortex-M4 microcontrollers. Our implementation realizes new speed-records for PAKE and X25519 Diffie-Hellman for the ARM Cortex M4 architecture.