No abstract

Cyber Physical Systems (CPS) is an emerging computing paradigm that is becoming prevalent in various technologies. Achieving a trustworthy CPS requires us to build mechanisms that ensure the integrity and authenticity of these systems. Fortunately with the new advancements in semiconductor-based technologies, in particular Physical Unclonable Functions (PUFs), we have the potential to build secure couplings between cyber and physical substrates based on intrinsic physical material. In this paper, we share some thoughts on how to utilize the PUF technology for security in CPS. Based on a composition approach, we illustrate the benefits of combining multiple PUF elements, with some inherently bias factor, into one randomly secure and strong system-level PUF. Keywords-Cyber-Physical System (CPS), Physical Unclonable Functions (PUFs), security978-1-4577-9538-2/11/$26.00 ©2011 IEEE

Effective suturing remains key to achieving successful outcomes in corneal surgery, especially anterior lamellar keratoplasty and full thickness transplantation. Limitations in the technique may result in complications such as wound leak, infection, or high astigmatism post corneal graft. By using a systematic approach, this study reviews articles and conducts content analysis based on update 2020 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria). The aim of this paper is to summarize the state of the art of corneal suturing techniques for every type of corneal transplant and patient age and also their outcomes regarding astigmatism and complications. Future developments for corneal transplantation will be also discussed. This is important because especially the young surgeon must have knowledge of the implications of every suture performed in order to achieve consistent and predictable post-operative outcomes and also be aware of all the possible complications.

Security in resource-limited environments poses a great challenge as the nodes comprising such a network are severely limited in processing power and storage. Various security protocols have been proposed for sensor networks and RFID that try to mitigate this problem but they provide security on a point-to-point basis which is weak and easily vulnerable to a number of attacks. In this paper, we discuss architecture for a resource limited environment that enables these networks to achieve better security and reliability while being simple and efficient. Based on the architecture we develop noncryptographic security mechanisms using state machines for providing basic security services including authenticity and confidentiality. We also introduce the concept of Security Fusion where strong system level security properties are synthesized from weak point-to-point security properties. The strengths of these techniques are analysed so as to offer comparisons with conventional techniques.

Security fusion is a new paradigm in security for resource-constrained environments [20]. Following this paradigm, strong system-level security is achieved by combining weak primitives from multiple nodes. In this paper, we describe a fusion methodology based on state machine compositions. From the properties of compositions, we devise a challenge-response system that composes low-entropy state machines at individual nodes into one with higher entropy. We use built-in digital logic such as Physical Unclonable Functions (PUFs) to efficiently mass generate and distribute keys. In addition, we draw on the properties of compositions to reduce the key storage complexity at the infrastructure-level, with high coverage and early detectability at the system-level.978-1-4244-9906-9/11/$26.00 ©2011 IEEE