The continuous adoption of Near Field Communication (NFC) tags offers many new applications whose security is essential (e.g., contactless payments). In order to prevent flaws and attacks, we develop in this article a framework allowing us to analyse the underlying security protocols, taking into account the location of the agents and the transmission delay when exchanging messages. We propose two reduction results to render automatic verification possible relying on the existing verification tool ProVerif . Our first result allows one to consider a unique topology to catch all possible attacks. The second result simplifies the security analysis when considering Terrorist fraud. Then, based on these results, we perform a comprehensive case study analysis (27 protocols), in which we obtain new proofs of security for some protocols and detect attacks on some others.

For many modern applications like e.g., contactless payment, and keyless systems, ensuring physical proximity is a security goal of paramount importance. Formal methods have proved their usefulness when analysing standard security protocols. However, existing results and tools do not apply to e.g., distance bounding protocols that aims to ensure physical proximity between two entities. This is due in particular to the fact that existing models do not represent in a faithful way the locations of the participants, and the fact that transmission of messages takes time. In this paper, we propose several reduction results: when looking for an attack, it is actually sufficient to consider a simple scenario involving at most four participants located at some specific locations. These reduction results allow one to use verification tools (e.g. ProVerif, Tamarin) developed for analysing more classical security properties. As an application, we analyse several distance bounding protocols, as well as a contactless payment protocol.

Norway used e-voting in its last political election both in September 2011 and September 2013, with more than 28,000 voters using the e-voting option in 2011, and 70,000 in 2013. While some other countries use a black-box, proprietary voting solution, Norway has made its system publicly available. The underlying protocol, designed by Scytl, involves several authorities (a ballot box, a receipt generator, a decryption service, and an auditor). Of course, trusting the correctness and security of e-voting protocols is crucial in that context. In this paper, we propose a formal analysis of the protocol used in Norway, w.r.t. ballot secrecy, considering several corruption scenarios. We use a state-of-the-art definition of ballot secrecy, based on equivalence properties and stated in the applied pi-calculus.

While extensive research addresses the problem of establishing session keys through cryptographic protocols, relatively little work has appeared addressing the problem of revocation and update of long term keys. We present an API for symmetric key management on embedded devices that supports key establishment and revocation, and prove security properties of our design in the symbolic model of cryptography. Our API supports two modes of revocation: a passive mode where keys have an expiration time, and an active mode where revocation messages are sent to devices. For the first we show that once enough time has elapsed after the compromise of a key, the system returns to a secure state, i.e. the API is robust against attempts by the attacker to use a compromised key to compromise other keys or to keep the compromised key alive past its validity time. For the second we show that once revocation messages have been received the system immediately returns to a secure state. Notable features of our designs are that all secret values on the device are revocable, and the device returns to a functionally equivalent state after revocation is complete.