Group key establishment protocols: Pairing cryptography and verifiable secret sharing scheme

Thesis (Master)--Izmir Institute of Technology, Computer Engineering, Izmir, 2013Includes bibliographical references (leaves: 97-103)Text in English; Abstract: Turkish and Englishx, 154 leavesThe aim of this study is to establish a common secret key over an open network for a group of user to be used then symmetrical secure communication between them. There are two methods of GKE protocol which are key agreement and key distribution. Key agreement is a mechanism whereby the parties jointly establish a common secret. As to key distribution, it is a mechanism whereby one of the parties creates or obtains a secret value and then securely distributes it to other parties. In this study, both methods is applied and analyzed in two different GKE protocols. Desirable properties of a GKE are security and efficiency. Security is attributed in terms of preventing attacks against passive and active adversary. Efficiency is quantified in terms of computation, communication and round complexity. When constructing a GKE, the challenge is to provide security and efficiency according to attributed and quantified terms. Two main cryptographic tools are selected in order to handle the defined challenge. One of them is bilinear pairing which is based on elliptic curve cryptography and another is verifiable secret sharing which is based on multiparty computation. In this thesis, constructions of these two GKE protocols are studied along with their communication models, security and efficiency analysis. Also, an implementation of four-user group size is developed utilizing PBC, GMP and OpenSSL Libraries for both two protocols

Adaptable Group-Oriented Signature

A new type of signature is presented in this paper, named adaptable group-oriented signature. In contrast with traditional group-oriented signature, the new one laid a strong emphasis on how to improve the signer¡¯s efficiency. In fact, this new type of group-oriented signature can be seen as a type of designated verifier signature. In contrast with the ordinary designated verifier signature, it does not designate one member but several members to independently verify the signature. The designated members, who can independently verify the signature, come into a group. This scheme can ensure the anonymity of the verifiers. This type of signature can be used in such system that the compute resource is limited, such as the broadcast protocols of the mobile telephone in the mobile networks

EFFICIENT AND SCALABLE NETWORK SECURITY PROTOCOLS BASED ON LFSR SEQUENCES

The gap between abstract, mathematics-oriented research in cryptography and the engineering approach of designing practical, network security protocols is widening. Network researchers experiment with well-known cryptographic protocols suitable for different network models. On the other hand, researchers inclined toward theory often design cryptographic schemes without considering the practical network constraints. The goal of this dissertation is to address problems in these two challenging areas: building bridges between practical network security protocols and theoretical cryptography. This dissertation presents techniques for building performance sensitive security protocols, using primitives from linear feedback register sequences (LFSR) sequences, for a variety of challenging networking applications. The significant contributions of this thesis are: 1. A common problem faced by large-scale multicast applications, like real-time news feeds, is collecting authenticated feedback from the intended recipients. We design an efficient, scalable, and fault-tolerant technique for combining multiple signed acknowledgments into a single compact one and observe that most signatures (based on the discrete logarithm problem) used in previous protocols do not result in a scalable solution to the problem. 2. We propose a technique to authenticate on-demand source routing protocols in resource-constrained wireless mobile ad-hoc networks. We develop a single-round multisignature that requires no prior cooperation among nodes to construct the multisignature and supports authentication of cached routes. 3. We propose an efficient and scalable aggregate signature, tailored for applications like building efficient certificate chains, authenticating distributed and adaptive content management systems and securing path-vector routing protocols. 4. We observe that blind signatures could form critical building blocks of privacypreserving accountability systems, where an authority needs to vouch for the legitimacy of a message but the ownership of the message should be kept secret from the authority. We propose an efficient blind signature that can serve as a protocol building block for performance sensitive, accountability systems. All special forms digital signatures—aggregate, multi-, and blind signatures—proposed in this dissertation are the first to be constructed using LFSR sequences. Our detailed cost analysis shows that for a desired level of security, the proposed signatures outperformed existing protocols in computation cost, number of communication rounds and storage overhead

ID-based, proxy, threshold signature scheme

We propose the proxy threshold signature scheme with the application of elegant construction of verifiable delegating key in the ID-based infrastructure, and also with the bilinear pairings. The protocol satisfies the classical security requirements used in the proxy delegation of signing rights. The description of the system architecture and the possible application of the protocol in edge computing designs is enclosed

ID-based, proxy, threshold signature scheme

We propose the proxy threshold signature scheme with the application of elegant construction of verifiable delegating key in the ID-based infrastructure, and also with the bilinear pairings. The protocol satisfies the classical security requirements used in the proxy delegation of signing rights. The description of the system architecture and the possible application of the protocol in edge computing designs is enclosed

Theory and Practice of Cryptography and Network Security Protocols and Technologies

In an age of explosive worldwide growth of electronic data storage and communications, effective protection of information has become a critical requirement. When used in coordination with other tools for ensuring information security, cryptography in all of its applications, including data confidentiality, data integrity, and user authentication, is a most powerful tool for protecting information. This book presents a collection of research work in the field of cryptography. It discusses some of the critical challenges that are being faced by the current computing world and also describes some mechanisms to defend against these challenges. It is a valuable source of knowledge for researchers, engineers, graduate and doctoral students working in the field of cryptography. It will also be useful for faculty members of graduate schools and universities

Geometric Langlands Twists of N = 4 Gauge Theory from Derived Algebraic Geometry

We develop techniques for describing the derived moduli spaces of solutions to the equations of motion in twists of supersymmetric gauge theories as derived algebraic stacks. We introduce a holomorphic twist of N=4 supersymmetric gauge theory and compute the derived moduli space. We then compute the moduli spaces for the Kapustin-Witten topological twists as its further twists. The resulting spaces for the A- and B-twist are closely related to the de Rham stack of the moduli space of algebraic bundles and the de Rham moduli space of flat bundles, respectively. In particular, we find the unexpected result that the moduli spaces following a topological twist need not be entirely topological, but can continue to capture subtle algebraic structures of interest for the geometric Langlands program.Comment: 55 pages; minor correction

An Efficient and Provably Secure ID-Based Threshold Signcryption Scheme

Signcryption is a cryptographic primitive that performs digital signature and public key encryption simultaneously, at a lower computational costs and communication overheads than the signature-then-encryption approach. Recently, two identity-based threshold signcryption schemes[12],[26] have been proposed by combining the concepts of identity-based threshold signature and signcryption together. However, the formal models and security proofs for both schemes are not considered. In this paper, we formalize the concept of identity-based threshold signcryption and give a new scheme based on the bilinear pairings. We prove its confidentiality under the Decisional Bilinear Diffie-Hellman assumption and its unforgeability under the Computational Diffie-Hellman assumption in the random oracle model. Our scheme turns out to be more efficient than the two previously proposed schemes

A novel k-out-of-n Oblivious Transfer Protocols Based on Bilinear Pairings

Low bandwidth consumption is an important issue in a busy commercial network whereas time may not be so crucial, for example, the end-of-day financial settlement for commercial transactions in a day. In this paper, we construct a secure and low bandwidth-consumption k-out-of-n oblivious transfer scheme based on bilinear pairings. We analyze the security and efficiency of our scheme and conclude that our scheme is more secure and efficient in communication bandwidth consumption than most of the other existing oblivious transfer schemes that we know