Effects of azithromycin versus metronidazole– amoxicillin combination as an adjunct to nonsurgical periodontal therapy of generalized aggressive periodontitis

Objective: This study evaluated the short‑term clinical benefits of two systemic antibiotic regimes added to the nonsurgical periodontal treatment of generalized aggressive periodontitis.Materials and Methods: The patient records were reviewed and 45 patients were selected and divided into the following three groups: Scaling and root planning (SRP) only; SRP plus azithromycin (AZT group); and SRP plus metronidazole and amoxicillin (M + A group). The periodontal indexes were recorded at baseline and 3‑month posttherapy.Results: The periodontal parameters were improved in all groups 3‑month posttherapy. The scores were decreased more in the AZT and M + A groups than the controls, but this difference did not reach significance. In addition, the decrease in the plaque index from baseline to 3‑month in the AZT group was not significant.Conclusion: Nonsurgical therapy reduces the probing depth, clinical attachment level, and clinical inflammation findings. This healing tendency was observed in the AZT group despite the baseline plaque scores. Therefore, AZT might be active against the bacteria in dental biofilms.Keywords: Azithromycin, generalized aggressive periodontitis, metronidazole and amoxicillin, nonsurgical periodontal therapy, scaling and root plannin

PRF-ODH: Relations, Instantiations, and Impossibility Results

The pseudorandom-function oracle-Diffie--Hellman (PRF-ODH) assumption has been introduced recently to analyze a variety of DH-based key exchange protocols, including TLS 1.2 and the TLS 1.3 candidates, as well as the extended access control (EAC) protocol. Remarkably, the assumption comes in different flavors in these settings and none of them has been scrutinized comprehensively yet. In this paper here we therefore present a systematic study of the different PRF-ODH variants in the literature. In particular, we analyze their strengths relative to each other, carving out that the variants form a hierarchy. We further investigate the boundaries between instantiating the assumptions in the standard model and the random oracle model. While we show that even the strongest variant is achievable in the random oracle model under the strong Diffie--Hellman assumption, we provide a negative result showing that it is implausible to instantiate even the weaker variants in the standard model via algebraic black-box reductions to common cryptographic problems

Efficient Public-Key Distance Bounding Protocol

Distance bounding protocols become more and more important because they are the most accurate solution to defeat relay attacks. They consist of two parties: a verifier and a prover. The prover shows that (s)he is close enough to the verifier. In some applications such as payment systems, using public-key distance bounding protocols is practical as no pre-shared secret is necessary between the payer and the payee. However, public-key cryptography requires much more computations than symmetric key cryptography. In this work, we focus on the efficiency problem in public-key distance bounding protocols and the formal security proofs of them. We construct two protocols (one without privacy, one with) which require fewer computations on the prover side compared to the existing protocols, while keeping the highest security level. Our construction is generic based on a key agreement model. It can be instantiated with only one resp. three elliptic curve computations for the prover side in the two protocols, respectively. We proved the security of our constructions formally and in detail