A new construction for linkable secret handshake

National Research Foundation (NRF) Singapore; AXA Research Fun

A NEW UNLINKABLE SECRET HANDSHAKES SCHEME BASED ON ZSS

Secret handshakes (SH) scheme is a key agreement protocol between two members of the same group. Under this scheme two members share a common key if and only if they both belong to the same group. If the protocol fails none of the parties involved get any idea about the group affiliation of the other. Moreover if the transcript of communication is available to a third party, she/he does not get any information about the group affiliation of communicating parties. The concept of SH was given by Balfanz in 2003 who also gave a practical SH scheme using pairing based cryptography. The protocol proposed by Balfanz uses one time credential to insure that handshake protocol performed by the same party cannot be linked. Xu and Yung proposed SH scheme that achieve unlinkability with reusable credentials. In this paper, a new unlinkable secret handshakes scheme is presented. Our scheme is constructed from the ZSS signature and inspired on an identity based authenticated key agreement protocol, proposed by McCullagh et al. In recently proposed work most of unlinkable secret handshake schemes have either design flaw or security flaw, we proved the security of proposed scheme by assuming the intractability of the bilinear inverse Diffie-Hellman and k-CAA problems

PPAA: Peer-to-Peer Anonymous Authentication (Extended Version)

In the pursuit of authentication schemes that balance user privacy and accountability, numerous anonymous credential systems have been constructed. However, existing systems assume a client-server architecture in which only the clients, but not the servers, care about their privacy. In peer-to-peer (P2P) systems where both clients and servers are peer users with privacy concerns, no existing system correctly strikes that balance between privacy and accountability. In this paper, we provide this missing piece: a credential system in which peers are {\em pseudonymous} to one another (that is, two who interact more than once can recognize each other via pseudonyms) but are otherwise anonymous and unlinkable across different peers. Such a credential system finds applications in, e.g., Vehicular Ad-hoc Networks (VANets) and P2P networks. We formalize the security requirements of our proposed credential system, provide a construction for it, and prove the security of our construction. Our solution is efficient: its complexities are independent of the number of users in the system

Affiliation-Hiding Authentication with Minimal Bandwidth Consumption

Part 3: Lightweight AuthenticationInternational audienceAffiliation-Hiding Authentication (AHA) protocols have the seemingly contradictory property of enabling users to authenticate each other as members of certain groups, without revealing their affiliation to group outsiders. Of particular interest in practice is the group-discovering variant, which handles multiple group memberships per user. Corresponding solutions were only recently introduced, and have two major drawbacks: high bandwidth consumption (typically several kilobits per user and affiliation), and only moderate performance in scenarios of practical application.While prior protocols have O(n2) time complexity, where n denotes the number of affiliations per user, we introduce a new AHA protocol running in O(nlogn) time. In addition, the bandwidth consumed is considerably reduced. We consider these advances a major step towards deployment of privacy-preserving methods in constraint devices, like mobile phones, to which the economization of these resources is priceless

DSH: Deniable secret handshake framework

National Research Foundation (NRF) Singapor

Building Trust for Lambda-Congenial Secret Groups

Establishing trust while preserving privacy is a challenging research problem. In this paper we introduce lambda -congenial secret groups which allow users to recognize trusted partners based on common attributes while preserving their anonymity and privacy. Such protocols are different from authentication protocols, since the latter are based on identities, while the former are based on attributes. Introducing attributes in trust establishment allows a greater flexibility but also brings up several issues. In this paper, we investigate the problem of building trust with attributes by presenting motivating examples, analyzing the security requirements and giving an informal definition. We also survey one of the most related techniques, namely private matching, and finally present solutions based on it

Anonymous, authentic, and accountable resource management based on the E-cash paradigm

The prevalence of digital information management in an open network has driven the need to maintain balance between anonymity, authenticity and accountability (AAA). Anonymity allows a principal to hide its identity from strangers before trust relationship is established. Authenticity ensures the correct identity is engaged in the transaction even though it is hidden. Accountability uncovers the hidden identity when misbehavior of the principal is detected. The objective of this research is to develop an AAA management framework for secure resource allocations. Most existing resource management schemes are designed to manage one or two of the AAA attributes. How to provide high strength protection to all attributes is an extremely challenging undertaking. Our study shows that the electronic cash (E-cash) paradigm provides some important knowledge bases for this purpose. Based on Chaum-Pederson’s general transferable E-cash model, we propose a timed-zero-knowledge proof (TZKP) protocol, which greatly reduces storage spaces and communication overheads for resource transfers, without compromising anonymity and accountability. Based on Eng-Okamoto’s general divisible E-cash model, we propose a hypercube-based divisibility framework, which provides a sophisticated and flexible way to partition a chunk of resources, with different trade-offs in anonymity protection and computational costs, when it is integrated with different sub-cube allocation schemes. Based on the E-cash based resource management framework, we propose a privacy preserving service oriented architecture (SOA), which allows the service providers and consumers to exchange services without leaking their sensitive data. Simulation results show that the secure resource management framework is highly practical for missioncritical applications in large scale distributed information systems

Flexible Framework for Secret Handshakes (Multi-Party Anonymous and Un-observable Authentication)

In the society increasingly concerned with the erosion of privacy, privacy-preserving techniques are becoming very important. This motivates research in cryptographic techniques offering built-in privacy. A secret handshake is a protocol whereby participants establish a secure, anonymous and unobservable communication channel only if they are members of the same group. This type of ``private authentication is a valuable tool in the arsenal of privacy-preserving cryptographic techniques. Prior research focused on 2-party secret handshakes with one-time credentials. This paper breaks new ground on two accounts: (1) it shows how to obtain secure and efficient secret handshakes with reusable credentials, and (2) it represents the first treatment of group (or {\em multi-party}) secret handshakes, thus providing a natural extension to the secret handshake technology. An interesting new issue encountered in multi-party secret handshakes is the need to ensure that all parties are indeed distinct. (This is a real challenge since the parties cannot expose their identities.) We tackle this and other challenging issues in constructing GCD -- a flexible framework for secret handshakes. The proposed framework lends itself to many practical instantiations and offers several novel and appealing features such as self-distinction and strong anonymity with reusable credentials. In addition to describing the motivation and step-by-step construction of the framework, this paper provides a thorough security analysis and illustrates two concrete framework instantiations

Oblivious Handshakes and Sharing of Secrets of Privacy-Preserving Matching and Authentication Protocols

The objective of this research is focused on two of the most important privacy-preserving techniques: privacy-preserving element matching protocols and privacy-preserving credential authentication protocols, where an element represents the information generated by users themselves and a credential represents a group membership assigned from an independent central authority (CA). The former is also known as private set intersection (PSI) protocol and the latter is also known as secret handshake (SH) protocol. In this dissertation, I present a general framework for design of efficient and secure PSI and SH protocols based on similar message exchange and computing procedures to confirm “commonality” of their exchanged information, while protecting the information from each other when the commonalty test fails. I propose to use the homomorphic randomization function (HRF) to meet the privacy-preserving requirements, i.e., common element/credential can be computed efficiently based on homomorphism of the function and uncommon element/credential are difficult to derive because of the randomization of the same function. Based on the general framework two new PSI protocols with linear computing and communication cost are proposed. The first protocol uses full homomorphic randomization function as the cryptographic basis and the second one uses partial homomorphic randomization function. Both of them achieve element confidentiality and private set intersection. A new SH protocol is also designed based on the framework, which achieves unlinkability with a reusable pair of credential and pseudonym and least number of bilinear mapping operations. I also propose to interlock the proposed PSI protocols and SH protocol to design new protocols with new security properties. When a PSI protocol is executed first and the matched elements are associated with the credentials in a following SH protocol, authenticity is guaranteed on matched elements. When a SH protocol is executed first and the verified credentials is used in a following PSI protocol, detection resistance and impersonation attack resistance are guaranteed on matching elements. The proposed PSI and SH protocols are implemented to provide privacy-preserving inquiry matching service (PPIM) for social networking applications and privacy-preserving correlation service (PAC) of network security alerts. PPIM allows online social consumers to find partners with matched inquiries and verified group memberships without exposing any information to unmatched parties. PAC allows independent network alert sources to find the common alerts without unveiling their local network information to each other