Biblio

Recent works showed that websites can detect browser extensions that users install and websites they are logged into. This poses significant privacy risks, since extensions and Web logins that reflect user's behavior, can be used to uniquely identify users on the Web. This paper reports on the first large-scale behavioral uniqueness study based on 16,393 users who visited our website. We test and detect the presence of 16,743 Chrome extensions, covering 28% of all free Chrome extensions. We also detect whether the user is connected to 60 different websites. We analyze how unique users are based on their behavior, and find out that 54.86% of users that have installed at least one detectable extension are unique; 19.53% of users are unique among those who have logged into one or more detectable websites; and 89.23% are unique among users with at least one extension and one login. We use an advanced fingerprinting algorithm and show that it is possible to identify a user in less than 625 milliseconds by selecting the most unique combinations of extensions. Because privacy extensions contribute to the uniqueness of users, we study the trade-off between the amount of trackers blocked by such extensions and how unique the users of these extensions are. We have found that privacy extensions should be considered more useful than harmful. The paper concludes with possible countermeasures.

This work presents a highly reliable and tamper-resistant design of Physical Unclonable Function (PUF) exploiting Resistive Random Access Memory (RRAM). The RRAM PUF properties such as uniqueness and reliability are experimentally measured on 1 kb HfO2 based RRAM arrays. Firstly, our experimental results show that selection of the split reference and offset of the split sense amplifier (S/A) significantly affect the uniqueness. More dummy cells are able to generate a more accurate split reference, and relaxing transistor's sizes of the split S/A can reduce the offset, thus achieving better uniqueness. The average inter-Hamming distance (HD) of 40 RRAM PUF instances is 42%. Secondly, we propose using the sum of the read-out currents of multiple RRAM cells for generating one response bit, which statistically minimizes the risk of early retention failure of a single cell. The measurement results show that with 8 cells per bit, 0% intra-HD can maintain more than 50 hours at 150 °C or equivalently 10 years at 69 °C by 1/kT extrapolation. Finally, we propose a layout obfuscation scheme where all the S/A are randomly embedded into the RRAM array to improve the RRAM PUF's resistance against invasive tampering. The RRAM cells are uniformly placed between M4 and M5 across the array. If the adversary attempts to invasively probe the output of the S/A, he has to remove the top-level interconnect and destroy the RRAM cells between the interconnect layers. Therefore, the RRAM PUF has the “self-destructive” feature. The hardware overhead of the proposed design strategies is benchmarked in 64 × 128 RRAM PUF array at 65 nm, while these proposed optimization strategies increase latency, energy and area over a naive implementation, they significantly improve the performance and security.

Aliasing is a known source of challenges in the context of imperative object-oriented languages, which have led to important advances in type systems for aliasing control. However, their large-scale adoption has turned out to be a surprisingly difficult challenge. While new language designs show promise, they do not address the need of aliasing control in existing languages. This paper presents a new approach to isolation and uniqueness in an existing, widely-used language, Scala. The approach is unique in the way it addresses some of the most important obstacles to the adoption of type system extensions for aliasing control. First, adaptation of existing code requires only a minimal set of annotations. Only a single bit of information is required per class. Surprisingly, the paper shows that this information can be provided by the object-capability discipline, widely-used in program security. We formalize our approach as a type system and prove key soundness theorems. The type system is implemented for the full Scala language, providing, for the first time, a sound integration with Scala's local type inference. Finally, we empirically evaluate the conformity of existing Scala open-source code on a corpus of over 75,000 LOC.