Biblio

Physically Unclonable Functions (PUFs) are hardware-based security primitives that utilize manufacturing process variations to realize binary keys (Weak PUFs) or binary functions (Strong PUFs). This primitive is desirable for key generation and authentication in constrained devices, due to its low power and low area overhead. However, in recent years many research papers are focused on the vulnerability of PUFs to modeling attacks. This attack is possible because the PUFs challenge and response exchanges are usually transmitted over communication channel without encryption. Thus, an attacker can collect challenge-response pairs and use it as input into a learning algorithm, to create a model that can predict responses given new challenges. In this paper we introduce a serial and a parallel novel 64-bits memory-based controlled PUF (Mc-PUF) architecture for device authentication that has high uniqueness and randomness, reliable, and resilient against modeling attacks. These architectures generate a response by utilizing bits extracted from the fingerprint of a synchronous random-access memory (SRAM) PUF with a control logic. The synthesis of the serial architecture yielded an area of 1.136K GE, while the parallel architecture was 3.013K GE. The best prediction accuracy obtained from the modeling attack was 50%, which prevents an attacker from accurately predicting responses to future challenges. We also showcase the scalability of the design through XOR-ing several Mc-PUFs, further improving upon its security and performance. The remainder of the paper presents the proposed architectures, along with their hardware implementations, area and power consumption, and security resilience against modeling attacks. The 3-XOR Mc-PUF had the greatest overhead, but it produced the best randomness, uniqueness, and resilience against modeling attacks.

This paper presents a case study on the use and implementation of the Qualified Digital Signature. Problematics such as the degree of use, security and authenticity of Qualified Digital Signature and the publication and dissemination of documents signed in digital format are analyzed. In order to support the case study, a methodology was adopted that included interviews with municipalities that are part of the Intermunicipal Community of the region of Leiria and a computer application was developed that allowed to analyze the documents available in the institutional websites of the municipalities, the ones that were digitally signed. The results show that institutional websites are already providing documentation with Qualified Digital Signature and that the level of trust and authenticity regarding their use is considered to be mostly very positive.

Authentication is achieved by using different techniques, like using smart-card, identity password and biometric techniques. Some of the proposed schemes use a single factor for authentication while others combine multiple ways to provide multi-factor authentication for better security. lately, a new scheme for multi-factor authentication was presented by Cao and Ge and claimed that their scheme is highly secure and can withstand against all known attacks. In this paper, it is revealed that their scheme is still vulnerable and have some loopholes in term of reflection attack. Therefore, an improved scheme is proposed to overcome the security weaknesses of Cao and Ge's scheme. The proposed scheme resists security attacks and secure. Formal testing is carried out under a broadly-accepted simulated tool ProVerif which demonstrates that the proposed scheme is well secure.