Search results

How can a buyer legitimately benefit from group discounts while preserving his privacy? We show how this can be achieved when buyers can use their own computing device (e.g. smartphone or computer) to perform a purchase. Specifically, we present a protocol for privacy-preserving group discounts. The protocol allows a group of buyers to prove how many they are without disclosing their identities. Coupled with an anonymous payment system, this allows group discounts to be compatible with buyer privacy. ; This work was partly funded by Google through a Faculty Research Award to the first author, who is also partially supported by the Government of Catalonia through an ICREA Acadèmia Prize. The following partial supports are also gratefully acknowledged: the Spanish Government under projects TIN2011-27076-C03-01 "CO-PRIVACY" and CONSOLIDER INGENIO 2010 CSD2007-00004 "ARES", and the European Commission under FP7 projects "DwB" and "Inter-Trust".

Part 11: Privacy II ; International audience ; We consider the following problem: two parties have each a private function, for example one that outputs the party's preferences on a set of alternatives; they wish to compute the distance between their functions without any of the parties revealing its function to the other. The above problem is extremely important in the context of social, political or business networks, whenever one wishes to find friends or partners with similar interests without having to disclose one's interests to everyone. We provide protocols that solve the above problem for several types of functions. Experimental work demonstrates that privacy preservation does not significantly distort the computed distances.

Vehicular ad hoc networks (VANETs) allow vehicle-to-vehicle communication and, in particular, vehicle-generated announcements. Provided that the trustworthiness of such announcements can be guaranteed, they can greatly increase the safety of driving. A new system for vehicle-generated announcements is presented that is secure against external and internal attackers attempting to send fake messages. Internal attacks are thwarted by using an endorsement mechanism based on threshold signatures. Our system outperforms previous proposals in message length and computational cost. Three different privacy-preserving variants of the system are also described to ensure that vehicles volunteering to generate and/or endorse trustworthy announcements do not have to sacrifice their privacy. ; This work was partly supported by the Spanish Government through projects TSI2007-65406-C03-01 "E-AEGIS" and CONSOLIDER INGENIO 2010 CSD2007- 00004 "ARES", and by the Government of Catalonia under grant 2005 SGR 00446.

Wireless Sensor Networks (WSN) are formed by nodes with limited computational and power resources. WSNs are finding an increasing number of applications, both civilian and military, most of which require security for the sensed data being collected by the base station from remote sensor nodes. In addition, when many sensor nodes transmit to the base station, the implosion problem arises. Providing security measures and implosion-resistance in a resource-limited environment is a real challenge. This article reviews the aggregation strategies proposed in the literature to handle the bandwidth and security problems related to many-to-one transmission in WSNs. Recent contributions to secure lossless many-to-one communication developed by the authors in the context of several Spanish-funded projects are surveyed. Ongoing work on the secure lossy many-to-one communication is also sketched.