94 research outputs found
Hardware Implementation of the GPS authentication
In this paper, we explore new area/throughput trade- offs for the Girault,
Poupard and Stern authentication protocol (GPS). This authentication protocol
was selected in the NESSIE competition and is even part of the standard ISO/IEC
9798. The originality of our work comes from the fact that we exploit a fixed
key to increase the throughput. It leads us to implement GPS using the Chapman
constant multiplier. This parallel implementation is 40 times faster but 10
times bigger than the reference serial one. We propose to serialize this
multiplier to reduce its area at the cost of lower throughput. Our hybrid
Chapman's multiplier is 8 times faster but only twice bigger than the
reference. Results presented here allow designers to adapt the performance of
GPS authentication to their hardware resources. The complete GPS prover side is
also integrated in the network stack of the PowWow sensor which contains an
Actel IGLOO AGL250 FPGA as a proof of concept.Comment: ReConFig - International Conference on ReConFigurable Computing and
FPGAs (2012
Robust PDF Files Forensics Using Coding Style
Identifying how a file has been created is often interesting in security. It
can be used by both attackers and defenders. Attackers can exploit this
information to tune their attacks and defenders can understand how a malicious
file has been created after an incident. In this work, we want to identify how
a PDF file has been created. This problem is important because PDF files are
extremely popular: many organizations publish PDF files online and malicious
PDF files are commonly used by attackers. Our approach to detect which software
has been used to produce a PDF file is based on coding style: given patterns
that are only created by certain PDF producers. We have analyzed the coding
style of 900 PDF files produced using 11 PDF producers on 3 different Operating
Systems. We have obtained a set of 192 rules which can be used to identify 11
PDF producers. We have tested our detection tool on 508836 PDF files published
on scientific preprints servers. Our tool is able to detect certain producers
with an accuracy of 100%. Its overall detection is still high (74%). We were
able to apply our tool to identify how online PDF services work and to spot
inconsistency
Boolean Functions and Distance Bounding
Distance bounding protocols are a critical mechanism of wireless technologies such as RFID or ZigBee. They aim to enforce a stronger definition of authentication by preventing any kind of the relay attack, namely the distance fraud, the mafia fraud and the terrorist fraud. This paper aims to define the Boolean functions used in the distance bounding protocols based on the work of Hancke and Kuhn. Indeed, the choice of these functions has never been discussed despite the considerable literature. We define the criteria on the function needed to defeat each fraud
(Un)Safe Browsing
Users often accidentally or inadvertently click ma- licious phishing or malware website links, and in doing so they sacrifice secret information and sometimes even fully compromise their devices. These URLs are intelligently scripted to remain inconspicuous over the Internet. In light of the ever increasing number of such URLs, new ingenious strategies have been in- vented to detect them and inform the end user when he is tempted to access such a link. The Safe Browsing technique provides an exemplary service to identify unsafe websites and notify users and webmasters allowing them to protect themselves from harm. In this work, we show how to turn Google Safe Browsing services against itself and its users. We propose several Distributed Denial- of-Service attacks that simultaneously affect both the Google Safe Browsing server and the end user. Our attacks leverage on the false positive probability of the data structures used for malicious URL detection. This probability exists because a trade- off was made between Google's server load and client's memory consumption. Our attack is based on the forgery of malicious URLs to increase the false positive probability. Finally we show how Bloom filter combined with universal hash functions and prefix lengthening can fix the problem
Time Distortion Anonymization for the Publication of Mobility Data with High Utility
An increasing amount of mobility data is being collected every day by
different means, such as mobile applications or crowd-sensing campaigns. This
data is sometimes published after the application of simple anonymization
techniques (e.g., putting an identifier instead of the users' names), which
might lead to severe threats to the privacy of the participating users.
Literature contains more sophisticated anonymization techniques, often based on
adding noise to the spatial data. However, these techniques either compromise
the privacy if the added noise is too little or the utility of the data if the
added noise is too strong. We investigate in this paper an alternative
solution, which builds on time distortion instead of spatial distortion.
Specifically, our contribution lies in (1) the introduction of the concept of
time distortion to anonymize mobility datasets (2) Promesse, a protection
mechanism implementing this concept (3) a practical study of Promesse compared
to two representative spatial distortion mechanisms, namely Wait For Me, which
enforces k-anonymity, and Geo-Indistinguishability, which enforces differential
privacy. We evaluate our mechanism practically using three real-life datasets.
Our results show that time distortion reduces the number of points of interest
that can be retrieved by an adversary to under 3 %, while the introduced
spatial error is almost null and the distortion introduced on the results of
range queries is kept under 13 % on average.Comment: in 14th IEEE International Conference on Trust, Security and Privacy
in Computing and Communications, Aug 2015, Helsinki, Finlan
Teaching Security with CTF-like challenges
National audienceWe present a course given at ENSIMAG which is an introduction to security. The originality of this course is that challenges are given to the students during the labs and at the mock/final exams. It may give you ideas for your courses
A Privacy Analysis of Google and Yandex Safe Browsing
Google and Yandex Safe Browsing are popular services included in many webbrowsers to prevent users from visiting phishing or malware website links. If Safe Browsing servicesprotect their users from losing private information, they also require that their servers receivebrowsing information on the very same users. In this paper, we present an analysis of Googleand Yandex Safe Browsing services from a privacy perspective. We quantify the privacy providedby these services by analyzing the possibility of re-identifying a URL visited by a client. Wehence challenge Google’s privacy policies where they claim that Google can not recover URLsvisited by its users. Our analysis and experimental results show that Google and Yandex SafeBrowsing can potentially be used as a tool to track specific classes of individuals. Additionally, ourinvestigations on the data currently included in Yandex Safe Browsing provides a concrete set ofURLs/domains that can be re-identified without much effort
Performances of Cryptographic Accumulators
International audienceCryptographic accumulators are space/time efficient data structures used to verify if a value belongs to a set. They have found many applications in networking and distributed systems since their in- troduction by Benaloh and de Mare in 1993. Despite this popularity, there is currently no performance evaluation of the different existing de- signs. Symmetric and asymmetric accumulators are used likewise without any particular argument to support either of the design. We aim to es- tablish the speed of each design and their application's domains in terms of their size and the size of the values
Matriochka symmetric Boolean functions
International audienceWe present the properties of a new class of Boolean functions defined as the sum of m symmetric functions with decreasing number of variables and degrees. The choice of this construction is justified by the possibility to study these functions by using tools existing for symmetric functions. On the one hand we show that the synthesis is well understood and give an upper bound on the gate complexity. On the other hand, we investigate the Walsh spectrum of the sum of two functions and get explicit formulae for the case of degree at most three
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