Privacy safeguards and online anonymity

In a world that is increasingly more connected, digital citizens, actively or passively accept to transmit information, part of which are “personal data”. This information is often collected and elaborated by third parties to infer further knowledge about users. The act of gathering the data is commonly called “tracking” and can be performed through several means. The act of analysing and processing those data and relate them to the individual is called “profiling”. The aim of this JRC Technical report is to be an instrument of support for the Digital Citizens to help them to protect and to manage their privacy during online activities. After a brief introduction in Chapter 1, the following chapter is dedicated to the description of two legitimate use-cases to track and profile users on-line, namely target advertising and personalisation of the user experience. Chapter 3 and 4 identify and analyse the set of techniques currently used by online digital providers to track citizens and profile them based on their online behaviour. Chapter 5 deals with some of the available tools cited in chapter 6 that could be helpful to protect the privacy while browsing online. Chapter 6 aims to raise awareness among users and provide some guidelines to address specific issues related to privacy through a multidisciplinary approach. The report concludes highlighting the importance of raising awareness among digital users and empower them through education, technical and legal tools, including the General Data Protection Regulation (GDPR) to overcome possible privacy issues.JRC.E.3-Cyber and Digital Citizens' Securit

New experiments for cryptanalysis on elliptic curves

The work of this thesis is focused on improving some tools commonly used for cryptoanalytical applications on elliptic curves, and some of them can be applied also when performing modular arithmetic in a more general context than the cryptological one. In chapter 1 it is given an introduction to the NVidia CUDA programming model and described some problems that can appear while writing code that must run on graphic processing units. In chapter 2 it is described a full implementation for single-instruction multiple-data architectures of a fast modular arithmetic library, with emphasis on the modular inversion. It is presented a variant of the Stein's algorithm that reduces divergence among thread and allows to consider it as a good alternative (for sufficiently big prime fields) to the branch-free algorithm based on Euler-Fermat theorem. In chapter 3 it is discussed the Rho-Pollard implementation for single-instruction multipledata architectures that uses the negation maps. It is presented also a variant of the classical iterating function of the Rho-Pollard algorithm to reduce the overhead to check for fruitless cycles. Chapter 4 contains the description of an experimental work performed on SAGE and aimed to apply the Smart's attack on anomalous elliptic curves (defined on prime fields) to a curve defined over a ring Zn1n2 with n1n2 points. To realize these experiments, the author, implemented into SAGE a complete system of addition laws for elliptic curves over rings, and the functions to perform arithmetic on polyadic numbers

Parallelized Pollard's Rho algorithm for ECDLP on Graphic Cards

The recent introduction by NVidia of Compute Unified Device Architecture (CUDA) libraries for High Performance Computing on Graphic Processing Units has started the trend of video cards for resolution of many computationally hard problems in different areas like fluid dynamics, molecular dynamics, computer vi- sion and astrophysics. In this paper we show how CUDA libraries and hardware can be introduced in cryptography as a cryptoanalytic tool.We describe an implementation of a parallelized Pollard’s rho attack on ECDLP, based upon recent results about the optimization of Pollard’s rho method and enhanced by some ”ad-hoc” choices for CUD

Role of non-neoplastic portal vein thrombosis in the natural history of patients with cirrhosis and first diagnosis of hepatocellular carcinoma

Background aims: Hepatocellular carcinoma (HCC) can increase the risk of non-neoplastic portal vein thrombosis (PVT) in cirrhosis. However, natural history of PVT and its prognostic role in HCC patients are unknown. Approach results: Consecutive cirrhotic HCC patients undergoing laparoscopic ablation were retrospectively evaluated and followed-up to 36 months. HCC and PVT characteristics and evolution were reviewed. PVT was categorized according to lumen occupancy (≤ 50%, > 50% < 100% and = 100%) and extension to other veins. Evolution of thrombosis was considered at 1 year from diagnosis. Variables associated with presence of PVT and evolution patterns were analyzed, as well as their impact on survival. Seven-hundreds-fifty patients were included, 88 with PVT. On multivariate analysis, the occurrence of PVT at HCC diagnosis was associated with pre-treatment total tumor volume (p < 0.001) and clinically-significant portal hypertension (p = 0.005). During follow-up, 46 de novo PVT occurred, 27/46 (58.7%) in presence of viable tumor. Among 115 PVT diagnosed in presence of HCC, 83 had available radiological follow-up, and 22 were anticoagulated. The 'complete/progressive' evolution pattern was associated with non-response to HCC treatment in non-anticoagulated patients. The presence of PVT was independently associated with lower overall survival, particularly when progressive or occlusive (p < 0.001). A higher competing risk of death emerged for 'complete and progressive' PVT, both for HCC-related (p < 0.001) and non-HCC-related (p = 0.002) death. Conclusions: HCC represents an independent risk factor for the occurrence and progression of PVT in cirrhosis. Since progressive and occlusive PVT seems to be an independent factor associated with mortality, screening and prompt treatment of this complication should be considered