Subversion-Resistant Simulation (Knowledge) Sound NIZKs

In ASIACRYPT 2016, Bellare, Fuchsbauer, and Scafuro studied the security of non-interactive zero-knowledge (NIZK) arguments in the face of parameter subversion. They showed that achieving subversion soundness (soundness without trusting to the third party) and standard zero-knowledge is impossible at the same time. On the positive side, in the best case, they showed that one can achieve subversion zero-knowledge (zero-knowledge without trusting to the third party) and soundness at the same time. In this paper, we show that one can amplify their best positive result and construct NIZK arguments that can achieve subversion zero-knowledge and $\textit{simulation}$ (knowledge) soundness at the same time. Simulation (knowledge) soundness is a stronger notion in comparison with (knowledge) soundness, as it also guarantees non-malleability of proofs. Such a stronger security guarantee is a must in practical systems. To prove the result, we show that given a NIZK argument that achieves Sub-ZK and (knowledge) soundness, one can use an OR-based construction to define a new language and build a NIZK argument that will guarantee Sub-ZK and $\textit{simulation}$ (knowledge) soundness at the same time. We instantiate the construction with the state-of-the-art zk-SNARK proposed by Groth [Eurocrypt 2016] and obtain an efficient SNARK that guarantees Sub-ZK and simulation knowledge soundness

Perifollicular Purpura as the first sign of Scurvy: A case report

Abstract: Scurvy is caused by ascorbic acid deficiency and although it is rare nowadays, still should be considered. In this paper a patient who was referred with perifollicular purpura and joint pain is presented. Patient’s history revealed that he was a known case of ulcerative colitis receiving sulfadiazine for three years. He had not consumed raw vegetables and fruits during this period. One week before admission, purpura appeared on the extremities and to a lesser degree on the trunk expanding in some areas. Arthritis was superimposed too. On the basis of above findings, vitamin C deficiency was suggested and 1500 mg/day of vitamin C was started orally. After three weeks, skin lesions and joint pain disappeared. Keywords: Scurvy, Vit.C deficiency, Purpur