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1,103 results · page 42 of 46
Anguraj Baskar, R. Ramanujam, S. P. Suresh
No abstract is available for this record.
Michel Abdalla⋆, Céline Chevalier, David Pointcheval
No abstract is available for this record.
Jan Camenisch, Aggelos Kiayias, Moti Yung
No abstract is available for this record.
圭介 田中, Keisuke Tanaka, 恵太 草川, Keita Xagawa
No abstract is available for this record.
Ueli Maurer
No abstract is available for this record.
Han Zhu, Xiaohong Wu, Yonggen Gu
As Zero-Knowledge proof plays a more and moreimportant role in modern cryptography, the need for formalanalysis becomes more urgent. In this paper, we make use offormal methods to establish a Zero-Knowledge result. The formalmodel is Probabilistic Applied Pi and the Zero-Knowledge proofis Hamiltonian cycle. By this example, our preliminary workshows how Zero-Knowledge can be modeled in formal modelssuch as process calculi and how to establish a Zero-Knowledgeproof by checking equivalence in the model.
Andrew Chi-Chih Yao, Frances Yao, Yunlei Zhao
No abstract is available for this record.
Michael Backes, Cătălin Hriţcu, Matteo Maffei
This paper presents the first type system for statically analyzing security protocols that are based on zero-knowledge proofs. We show how certain properties offered by zero-knowledge proofs can be characterized in terms of authorization policies and statically enforced by a type system. The analysis is modular and compositional, and provides security proofs for an unbounded number of protocol executions. We develop a new type-checker that conducts the analysis in a fully automated manner. We exemplify the applicability of our technique to real-world protocols by verifying the authenticity and secrecy properties of the Direct Anonymous Attestation (DAA) protocol. The analysis of DAA takes less than three seconds.
Joël Alwen, Abhi Shelat, Ivan Visconti
No abstract is available for this record.
Guomin Yang, Jing Chen, Duncan S. Wong, Xiaotie Deng · 5 authors
No abstract is available for this record.
Jungha Woo, Abhilasha Bhargav-Spantzel, Anna Squicciarini, Elisa Bertino
A main challenge in mobile commerce is to make it possible for users to manage their transaction histories from both online e-commerce transactions and in-person transactions. Such histories are typically useful to build credit or to establish trust based on past transactions. In this paper we propose an approach to manage electronic receipts on cellular devices by assuring their secure and privacy-preserving usage. We provide a comprehensive notion of transactions history including both on-line transaction and in-person transactions. We apply cryptographic protocols, such as secret sharing and zero knowledge proofs, in a potentially vulnerable and constrained setting. Specifically, our approach supports flexible strategies based on Shamir's secret sharing to cater to different user requirements and architectural constraints. In addition, aggregate zero knowledge proofs are used to efficiently support proofs of various receipt attributes. We have implemented the system on Nokia NFC cellular phones and report in the paper performance evaluation results.
Michael Backes, Matteo Maffei, Dominique Unruh
We devise an abstraction of zero-knowledge protocols that is accessible to a fully mechanized analysis. The abstraction is formalized within the applied pi-calculus using a novel equational theory that abstractly characterizes the cryptographic semantics of zero-knowledge proofs. We present an encoding from the equational theory into a convergent rewriting system that is suitable for the automated protocol verifier ProVerif. The encoding is sound and fully automated. We successfully used ProVerif to obtain the first mechanized analysis of (a simplified variant of) the Direct Anonymous Attestation (DAA) protocol. This required us to devise novel abstractions of sophisticated cryptographic security definitions based on interactive games. The analysis reported a novel attack on DAA that was overlooked in its existing cryptographic security proof. We propose a revised variant of DAA that we successfully prove secure using ProVerif.
Alfredo Espitia Beltran, Karen Ortega, Eduardo Romero, Iván Jaramillo
The main objective of this project was to design, develop and validate a digital signature in a security device for telemedicine applications. Medical domain requires high security conditions for archiving since the information to be protected contains images, diagnosis, personal information of the patients and physicians involved in the telemedicine process. The developed strategy consists in a USB device which allows proper authentication in the information system using a conventional public-private key scheme, through a zero knowledge proof algorithm that guarantees the privacy of the personal password. Once the user is accepted, the device also makes possible the generation of the digital signature required for generated documents.
Jianhua Ge
The private multi-party computation protocol proposed by Claude Crepeau etc.is not only complicated but very inefficient.This paper describes a new protocol with an efficient global commitment transfer sub-protocol.With a first two round string oblivious transfer,the protocol can avoid performing a large mount of bit oblivious transfers.And with bit commitment with XOR,zero knowledge proofs are very easy.This PMPC protocol is conceptually simple and more efficient.The security and complexity of the protocol are also discussed in this paper.
Xuan Yang, Zhaoping Yu, Bin Kang
A fair exchange protocol allows two parties to exchange items in a fair way so that either each party gets the other's item or neither party does. In this paper, we propose a key-exposure-free chameleon hashing scheme based on the discrete logarithm assumption, and prove that it enjoys all advantages of previous schemes: collision resistant, semantic security, message hiding and key exposure freeness. Using this new scheme as kernel, an efficient and secure chameleon-based optimistic fair exchange protocol is proposed. Unlike the vast majority of previously proposed protocols, above approach has no use for verifiably encrypted signature and does not use any zero knowledge proofs, which avoids most of the costly computations. The security of the newly devised protocol is also examined. It is showed that the proposed scheme is secure and efficient.
Jan Camenisch, Rafik Chaabouni, Abhi Shelat
No abstract is available for this record.
Michael Backes, Dominique Unruh
The abstraction of cryptographic operations by term algebras, called Dolev–Yao models, is essential in almost all tool-supported methods for proving security protocols. Recently significant progress was made in proving that Dolev–Yao models offering the core cryptographic operations such as encrypt ion and digital signatures can be sound with respect to actual cryptographic realizations and security definitions. Recent work, however, has started to extend Dolev–Yao models to more sophisticated operations with unique security features. Zero-knowledge proofs arguably constitute the most amazing such extension. In this paper, we first identify which additional properties a cryptographic (non-interactive) zero-knowledge proof needs to fulfill in order to serve as a computationally sound implementation of symbolic (Dolev–Yao style) zero-knowledge proofs; this leads to the novel definition of a symbolically-sound zero-knowledge proof system. We prove that even in the presence of arbitrary active adversaries, such proof systems constitute computationally sound implementations of symbolic zero-knowledge proofs. This yields the first computational soundness result for symbolic zero-knowledge proofs and the first such result against fully active adversaries of Dolev–Yao models that go beyond the core cryptographic operations.
Michael Backes, Dominique Unruh
The abstraction of cryptographic operations by term algebras, called Dolev-Yao models, is essential in almost all tool-supported methods for proving security protocols. Recently significant progress was made in proving that Dolev-Yao models offering the core cryptographic operations such as encryption and digital signatures can be sound with respect to actual cryptographic realizations and security definitions. Recent work, however, has started to extend Dolev-Yao models to more sophisticated operations with unique security features. Zero-knowledge proofs arguably constitute the most amazing such extension. In this paper, we first identify which additional properties a cryptographic zero-knowledge proof needs to fulfill in order to serve as a computationally sound implementation of symbolic (Dolev-Yao style) zero-knowledge proofs; this leads to the novel definition of a symbolically-sound zero-knowledge proof system. We prove that even in the presence of arbitrary active adversaries, such proof systems constitute computationally sound implementations of symbolic zero-knowledge proofs. This yields the first computational soundness result for symbolic zero-knowledge proofs and the first such result against fully active adversaries of Dolev-Yao models that go beyond the core cryptographic operations.
Simon Kramer
The thesis is about a breadth-first exploration of logical concepts in cryptography and their linguistic abstraction and model-theoretic combination in a comprehensive logical system, called CPL (for Cryptographic Protocol Logic ). We focus on two fundamental aspects of cryptography. Namely, the security of communication (as opposed to security of storage ) and cryptographic protocols (as opposed to cryptographic operators ). The logical concepts explored are the following. Primary concepts: the modal concepts of belief, knowledge, norms, provability, space, and time. Secondary concepts: belief with error control, individual and propositional knowledge, confidentiality norms, truth-functional and relevant (in particular, intuitionistic) implication, multiple and complex truth values, and program types. The distinguishing feature of CPL is that it unifies and refines a variety of existing approaches. This feature is the result of our wholistic conception of property-based (modal logics) and model-based (process algebra) formalisms. We illustrate the expressiveness of CPL on representative requirements engineering case studies. Further, we extend (core) CPL (qualitative time) with rational-valued time , i.e., time stamps, timed keys, and potentially drifting local clocks, to tCPL (quantitative time). Our extension is conservative and provides further evidence for Lamport's claim that adding real time to an untimed formalism is really simple. Furthermore, we sketch an extension of (core) CPL with a notion of probabilistic polynomial-time (PP) computation. We illustrate the expressiveness of this extended logic (ppCPL) on tentative formalisation case studies of fundamental and applied concepts. Fundamental concepts: (1) one-way function, (2) hard-core predicate, (3) computational indistinguishability, (4) ( n -party) interactive proof, and (5) ( n -prover) zero-knowledge. Applied concepts: (1) security of encryption schemes, (2) unforgeability of signature schemes, (3) attacks on encryption schemes, (4) attacks on signature schemes, and (5) breaks of signature schemes. In the light of logic, adding PP to a formalism for cryptographic protocols is perhaps also simple and can be achieved with an Ockham's razor extension of an existing core logic, namely CPL.
Sébastien Canard, Iwen Coisel, Jacques Traoré
No abstract is available for this record.
Éric Filiol
This paper presents a protocol aiming at proving that an encryption system contains structural weaknesses without disclosing any information on those weaknesses. A verifier can check in a polynomial time that a given property of the cipher system output has been effectively realized. This property has been chosen by the prover in such a way that it cannot been achieved by known attacks or exhaustive search but only if the prover indeed knows some undisclosed weaknesses that may effectively endanger the cryptosystem security. This protocol has been denoted zero-knowledge-like proof of cryptanalysis. In this paper, we apply this protocol to the Bluetooth core encryption algorithm E0, used in many mobile environments and thus we suggest that its security can seriously be put into question.
Jens Groth, Rafail Ostrovsky
No abstract is available for this record.
Andrew Chi-Chih Yao, Frances Yao, Yunlei Zhao
No abstract is available for this record.
Kyung-Min Eom, Chi-Ho Lin
The development of mobile telecommunication is emerging as a means of payment by replacing cash and credit cards. Information exchange is regarded as the most important communication system in conforming valid users. The most efficient means of securing information applies cryptography, which relies on small size information and demands its strict management. It is crucial to distribute key to cryptographic communication receiver without exposing key to the third party. The suggested protocol takes authentication and key distribution, which allows session key distribution after user authentication through an authentication center. However, the paper suggests an authentication and key distribution protocol which can be available to smartcard-suing personal communication system. This protocol takes ID-based key distribution method by means of Zero-Knowledge authentication proof which does not reveal secret information to the authentication center.