iUC: Flexible Universal Composability Made Simple

2019 ◽  
pp. 191-221 ◽  
Author(s):  
Jan Camenisch ◽  
Stephan Krenn ◽  
Ralf Küsters ◽  
Daniel Rausch
Keyword(s):  
Universal Composability

scholarly journals Universal Composability Notion for Functional Encryption Schemes

2013 ◽  
Vol 18 (3) ◽  
pp. 17-26 ◽  
Author(s):  
Rifki Sadikin ◽  
YoungHo Park ◽  
KilHoum Park ◽  
SangJae Moon
Keyword(s):  
Functional Encryption ◽  
Universal Composability ◽  
Encryption Schemes

Quantifying information flow in cryptographic systems

2014 ◽  
Vol 25 (2) ◽  
pp. 457-479 ◽  
Author(s):  
MICHAEL BACKES ◽  
BORIS KÖPF
Keyword(s):  
Information Flow ◽  
Upper Bound ◽  
Quantitative Information ◽  
Restricted Class ◽  
Universal Composability ◽  
Definition Of ◽  
Error Probabilities ◽  
Quantitative Information Flow ◽  
Secure Implementation ◽  
Simple Ideal

We provide a novel definition of quantitative information flow, called transmissible information, that is suitable for reasoning about informational-theoretically secure (or non-cryptographic) systems, as well as about cryptographic systems with their polynomially bounded adversaries, error probabilities, etc. Transmissible information captures deliberate communication between two processes, and it safely over-approximates the quantity of information that a process unintentionally leaks to another process.We show that transmissible information is preserved under universal composability, which constitutes the prevalent cryptographic notion of a secure implementation. This result enables us to lift quantitative bounds of transmissible information from simple ideal functionalities of cryptographic tasks to actual cryptographic systems.We furthermore prove a connection between transmissible information in the unconditional setting and channel capacity, based on the weak converse of Shannon's coding theorem. This connection enables us to compute an upper bound on the transmissible information for a restricted class of protocols, using existing techniques from quantitative information flow.

scholarly journals AnoA: A Framework for Analyzing Anonymous Communication Protocols

2017 ◽  
Vol 7 (2) ◽  
Author(s):  
Michael Backes ◽  
Aniket Kate ◽  
Praveen Manoharan ◽  
Sebastian Meiser ◽  
Esfandiar Mohammadi
Keyword(s):  
Quantitative Analysis ◽  
Complex Systems ◽  
Differential Privacy ◽  
The Internet ◽  
Anonymous Communication ◽  
Universal Composability ◽  
Multiplicative Factor ◽  
Generic Framework ◽  
The Subject ◽  
Definition Of

Anonymous communication (AC) protocols such as the widely used Tor network have been designed to provide anonymity over the Internet to their participating users. While AC protocols have been the subject of several security and anonymity analyses in the last years, there still does not exist a framework for analyzing these complex systems and their different anonymity properties in a unified manner.   In this work we present AnoA: a generic framework for defining, analyzing, and quantifying anonymity properties for AC protocols. In addition to quantifying the (additive) advantage of an adversary in an indistinguishability-based definition, AnoA uses a multiplicative factor, inspired from differential privacy. AnoA enables a unified quantitative analysis of well-established anonymity properties, such as sender anonymity, sender unlinkability, and relationship anonymity. AnoA modularly specifies adversarial capabilities by a simple wrapper-construction, called adversary classes. We examine the structure of these adversary classes and identify conditions under which it suffices to establish anonymity guarantees for single messages in order to derive guarantees for arbitrarily many messages. This then leads us to the definition of Plug’n’Play adversary classes (PAC), which are easy-to-use, expressive, and satisfy this condition. We prove that our framework is compatible with the universal composability (UC) framework and show how to apply AnoA to a simplified version of Tor against passive adversaries, leveraging a recent realization proof in the UC framework.

scholarly journals NTRU Implementation of Efficient Privacy-Preserving Location-Based Querying in VANET

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Bo Mi ◽  
Darong Huang ◽  
Shaohua Wan
Keyword(s):  
Performance Analysis ◽  
Real Time ◽  
Service Provider ◽  
Open Problem ◽  
Ad Hoc ◽  
Location Based Service ◽  
Universal Composability ◽  
Position Information ◽  
Distributed Structure ◽  
Is Security

The key for location-based service popularization in vehicular environment is security and efficiency. However, due to the constrained resources in vehicle-mounted system and the distributed structure of fog computation, disposing of the conflicts between real-time implementation and user’s privacy remains an open problem. Aiming at synchronously preserving the position information for users as well as the data proprietorship of service provider, an efficient location-based querying scheme is proposed in this paper. We argue that a recent scheme proposed by Jannati and Bahrak is time-consuming and vulnerable against active adaptive corruptions. Thus accordingly, a postquantum secure oblivious transfer protocol is devised based on efficient NTRU cryptosystem, which then serves as the understructure of a complete location-based querying scheme in ad hoc manner. The security of our scheme is proved under universal composability frame, while performance analysis is also carried out to testify its efficiency.

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