$\sf{ NTRUEncrypt}$is one of the most promising candidates for quantum-safe cryptography. In this paper, we focus on the$\sf{ NTRU743}$parameter set. We give a report on all known attacks against this parameter set and show that it delivers 256 bits of security against classical attackers and 128 bits of security against quantum attackers. We then present a parameter-dependent optimization using a tailored hierarchy of multiplication algorithms as well as the Intel AVX2 instructions, and show that this optimization is constant-time. Our implementation is two to three times faster than the reference implementation of$\sf{ NTRUEncrypt}$.

The U.S. Department of Transportation (USDOT) issued a proposed rule on January 12, 2017 to mandate vehicle-to-vehicle safety communications in light vehicles in the U.S. Cybersecurity and privacy are major challenges for such a deployment. We present a Security Credential Management System (SCMS) for vehicle-to-everything (V2X) communications in this paper, which has been developed by the Crash Avoidance Metrics Partners LLC under a cooperative agreement with the USDOT. This system design is currently transitioning from research to proof-of-concept and is a leading candidate to support the establishment of a nationwide Public Key Infrastructure for V2X security. It issues digital certificates to participating vehicles and infrastructure devices for trustworthy communications among them, which is necessary for safety and mobility applications that are based on V2X communications. The SCMS supports four main use cases, namely, bootstrapping, certificate provisioning, misbehavior reporting, and revocation. The main design goal is to provide both security and privacy to the largest extent reasonable and possible. To achieve a reasonable level of privacy in this context, vehicles are issued pseudonym certificates, and the generation and provisioning of those certificates are divided among multiple organizations. Given the large number of pseudonym certificates per vehicle, one of the main challenges is to facilitate efficient revocation of misbehaving or malfunctioning vehicles, while preserving privacy against attacks from insiders. The proposed SCMS supports all identified V2X use-cases and certificate types necessary for V2X communication security. This paper is based upon work supported by the USDOT. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors (“we”) and do not necessarily reflect the view of the USDOT.

We present a certificate access management system to support the USDOT's proposed rule on Vehicle-to-Vehicle (V2V) communications, Federal Motor Vehicle Safety Standard (FMVSS) No. 150. Our proposal, which we call Binary Hash Tree based Certificate Access Management (BCAM) eliminates the need for vehicles to have bidirectional connectivity with the Security Credential Management System (SCMS) for certificate update. BCAM significantly improves the ability of the SCMS to manage large-scale software and/or hardware compromise events. Vehicles are provisioned at the start of their lifetime with all the certificates they will need. However, certificates and corresponding private key reconstruction values are provided to the vehicle encrypted, and the keys to decrypt them are only made available to the vehicles shortly before the start of the validity periods of those certificates. Vehicles that are compromised can be effectively removed from the V2V system by preventing them from decrypting the certificates. We demonstrate that the system is feasible with a broadcast channel for decryption keys and other revocation information, even if that channel has a relatively low capacity.

Abstract We propose a circuit extension handshake for Tor that is forward secure against adversaries who gain quantum computing capabilities after session negotiation. In doing so, we refine the notion of an authenticated and confidential channel establishment (ACCE) protocol and define pre-quantum, transitional, and post-quantum ACCE security. These new definitions reflect the types of adversaries that a protocol might be designed to resist. We prove that, with some small modifications, the currently deployed Tor circuit extension handshake, ntor, provides pre-quantum ACCE security. We then prove that our new protocol, when instantiated with a post-quantum key encapsulation mechanism, achieves the stronger notion of transitional ACCE security. Finally, we instantiate our protocol with NTRU-Encrypt and provide a performance comparison between ntor, our proposal, and the recent design of Ghosh and Kate.