Biblio

Nowadays, the domain of Information System (IS) security is closely related to that of Risk Management (RM). As an immediate consequence, talking about and tackling the security of IS imply the implementation of a set of mechanisms that aim to reduce or eliminate the risk of IS degradations. Also, the high cadence of IS evolution requires careful consideration of corresponding measures to prevent or mitigate security risks that may cause the degradation of these systems. From this perspective, an access control service is subjected to a number of rules established to ensure the integrity and confidentiality of the handled data. During their lifecycle, the use or manipulation of Access Control Policies (ACP) is accompanied with several defects that are made intentionally or not. For many years, these defects have been the subject of numerous studies either for their detection or for the analysis of the risks incurred by IS to their recurrence and complexity. In our research works, we focus on the analysis and risk assessment of noncompliance anomalies in concrete instances of access control policies. We complete our analysis by studying and assessing the risks associated with the correlation that may exist between different anomalies. Indeed, taking into account possible correlations can make a significant contribution to the reliability of IS. Identifying correlation links between anomalies in concrete instances of ACP contributes in discovering or detecting new scenarios of alterations and attacks. Therefore, once done, this study mainly contributes in the improvement of our risk assessment model.

Due to the rapid development of internet in our daily life, protecting privacy has become a focus of attention. To create privacy-preserving database and prevent illegal user access the database, oblivious transfer with access control (OTAC) was proposed, which is a cryptographic primitive that extends from oblivious transfer (OT). It allows a user to anonymously query a database where each message is protected by an access control policy and only if the user' s attribute satisfy that access control policy can obtain it. In this paper, we propose a new protocol for OTAC by using elliptic curve cryptography, which is more efficient compared to the existing similar protocols. In our scheme, we also preserves user's anonymity and ensures that the user's attribute is not disclosed to the sender. Additionally, our construction guarantees the user to verify the correctness of messages recovered at the end of each transfer phase.

Access Control Policies (ACPs) evolve. Understanding the trends and evolution patterns of ACPs could provide guidance about the reliability and maintenance of ACPs. Our research goal is to help policy authors improve the quality of ACP evolution based on the understanding of trends and evolution patterns in ACPs We performed an empirical study by analyzing the ACP changes over time for two systems: Security Enhanced Linux (SELinux), and an open-source virtual computing platform (VCL). We measured trends in terms of the number of policy lines and lines of code (LOC), respectively. We observed evolution patterns. For example, an evolution pattern st1 → st2 says that st1 (e.g., "read") evolves into st2 (e.g., "read" and "write"). This pattern indicates that policy authors add "write" permission in addition to existing "read" permission. We found that some of evolution patterns appear to occur more frequently.