Software-based memory-erasure protocols are two-party communication protocols where a verifier instructs a computational device to erase its memory and send a proof of erasure. They aim at guaranteeing that low-cost IoT devices are free of malware by putting them back into a safe state without requiring secure hardware or physical manipulation of the device. Several software-based memory-erasure protocols have been introduced and theoretically analysed. Yet, many of them have not been tested for their feasibility, performance and security on real devices, which hinders their industry adoption. This article reports on the first empirical analysis of software-based memory-erasure protocols with respect to their security, erasure guarantees, and performance. The experimental setup consists of 3 modern IoT devices with different computational capabilities, 7 protocols, 6 hash-function implementations, and various performance and security criteria. Our results indicate that existing software-based memory-erasure protocols are feasible, although slow devices may take several seconds to erase their memory and generate a proof of erasure. We found that no protocol dominates across all empirical settings, defined by the computational power and memory size of the device, the network speed, and the required level of security. Interestingly, network speed and hidden constants within the protocol specification played a more prominent role in the performance of these protocols than anticipated based on the related literature. We provide an evaluation framework that, given a desired level of security, determines which protocols offer the best trade-off between performance and erasure guarantees.

A Proof of Secure Erasure (PoSE) is a communication protocol where a verifier seeks evidence that a prover has erased the memory on a given device within the time frame of the protocol execution. Designers of PoSE protocols have long been aware that, if a prover can outsource the computation of the memory erasure proof to another device, then their protocols are trivially defeated. As a result, most software-based PoSE protocols in the literature assume that provers are isolated during the protocol execution, that is, provers cannot receive help from a network adversary. Our main contribution is to show that this assumption is not necessary. We introduce formal models for PoSE protocols playing against provers aided by external conspirators and develop two PoSE protocols that we prove secure in this context. We reduce the requirement of isolation to the more realistic requirement that the communication with the external conspirator is relatively slow. Software-based protocols with such relaxed isolation assumptions are especially pertinent for low-end devices, where it is too costly to deploy sophisticated protection methods.

Distance-bounding protocols are security protocols with a time measurement phase used to detect relay attacks, whose security is typically measured against mafia-fraud and distance-fraud attacks. A prominent subclass of distance-bounding protocols, known as lookup-based protocols, use simple lookup operations to diminish the impact of the computation time in the distance calculation. Independent results have found theoretical lower bounds 12nn2+1 and 12n, where n is the number of time measurement rounds, on the security of lookup-based protocols against mafia and distance-fraud attacks, respectively. However, it is still an open question whether there exists a protocol achieving both security bounds. This article closes this question in two ways. First, we prove that the two lower bounds are mutually exclusive, meaning that there does not exist a lookup-based protocol that provides optimal protection against both types of attacks. Second, we provide a lookup-based protocol that approximates those bounds by a small constant factor. Our experiments show that, restricted to a memory size that linearly grows with n, our protocol offers strictly better security than previous lookup-based protocols against both types of fraud.

Various modern protocols tailored to emerging wire-less networks, such as body area networks, rely on the proximity and honesty of devices within the network to achieve their security goals. However, there does not exist a security framework that supports the formal analysis of such protocols, leaving the door open to unexpected flaws. In this article we introduce such a security framework, show how it can be implemented in the protocol verification tool Tamarin, and use it to find previously unknown vulnerabilities on two recent key exchange protocols.