Threshold Signature

In this paper, we propose a Directed threshold multisignature scheme without SDC. This signature scheme is applicable when the message is sensitive to the signature receiver; and the signatures are generated by the cooperation of a number of people from a given group of senders. In this scheme, any malicious set of signers cannot impersonate any other set of signers to forge the signatures. In case of forgery, it is possible to trace the signing set.

Identity-based systems have the property that a user’s public key can be easily calculated from his identity by a publicly available function. The bilinear pairings, especially Tate pairings, have high performance in cryptography. With the foundation of above two properties, we have proposed a new ID-Based (t, n) threshold signature scheme from Tate pairings. The scheme is proved secure that it can resist attacks including plaintext attack, recovery equation attack, conspiracy attack and impersonation attack. Furthermore, performance analysis shows that the proposed scheme is simple, efficient so that it will be suitable for an environment of finite bandwidth and low capability equipment.

We propose a robust proactive threshold signature scheme, a multisignature scheme and a blind signature scheme which work in any Gap Diffie-Hellman (GDH) group (where the Computational Diffie-Hellman problem is hard but the Decisional Diffie-Hellman problem is easy). Our constructions are based on the recently proposed GDH signature scheme of Boneh et al. [BLS]. Due to the instrumental structure of GDH groups and of the base scheme, it turns out that most of our constructions are simpler, more efficient and have more useful properties than similar existing constructions. We support all the proposed schemes with proofs under the appropriate computational assumptions, using the corresponding notions of security.

We introduce in this paper a new identity-based threshold signature (IBTHS) technique, which is based on a pair of intractable problems, residuosity and discrete logarithm. This technique relies on two difficult problems and offers an improved level of security relative to an on two difficult hard problems. The majority of the denoted IBTHS techniques are established on an individual difficult problem. Despite the fact that these methods are secure, however, a prospective solution of this sole problem by an adversary will enable him/her to recover the entire private data together with secret keys and configuration values of the associated scheme. Our technique is immune to the four most familiar attack types in relation to the signature schemes. Enhanced performance of our proposed technique is verified in terms of minimum cost of computations required by both of the signing algorithm and the verifying algorithm in addition to immunity to attacks. 1. INTRODUCTION In 1971, the idea of digital signature was first presented by Diffie and Helman [1] that enabled a signer in possession of a secrete key to sign a message, while anybody using a public key could perform verification of the signature. The notion of threshold signatures was presented by Desmedt [2] in 1987. A secret key, and correspondingly, the signing power, is shared to a collection of players in a (,) threshold signature scheme, where this is accomplished in a manner that any subset of players is able to collectively deliver a signature on the account of the group, whereas a subset composed of up to −1 players is incapable. The threshold signature is fundamental yet of a great significance cryptographic scheme that is due to its bifold function: by boosting the opportunity of the signing agency while simultaneously improving the safeguarding process against fraudulence through completing the learn process of the secret signature key for the antagonist. Subsequent to Desmedt's creation, in the commonly-named threshold cryptography domain, several threshold signature approaches incorporated on diverse premise were formulated, such as [3-8]. In order to streamline key management processes in certificate based public key setting, Shamir [9] in 1984, called for identity-based (ID-based) encryption and signature methods. Thenceforth, in the scope of this commonly-named ID-based cryptography, scores of identity-based cryptography techniques were put forward, such as the works of [10, 11]. The remarkably prominent tool has proposed bilinear pairing [10] in constructing identity-based cryptography primitives, where ID-based could be substituted for certificate-based in public key setting. This is of a special interest particularly when there is a requirement for efficient key management while moderate security is needed. The entire developed literature put forward on ID-based threshold group signature contains approaches that rely on an individual hard problem such as factoring,

Multipath routing in Wireless Sensors Networks (WSNs) is used in order to tolerate node failures and improve the reliability of data routing. To make a multipath routing algorithm adaptive to the sensitivity of the used application, communicating nodes in the network should be able to specify to which extent the established paths are disjoint. In this paper, we propose a

It has been demonstrated by Bellare, Neven, and Namprempre (Eurocrypt 2004) that identity-based signature schemes can be constructed from any PKI-based signature scheme. In this paper we consider the following natural extension: is there a generic construction of “identity-based signature schemes with additional properties” (such as identity-based blind signatures, verifiably encrypted signatures, ...) from PKI-based signature schemes with the same properties? Our results show that this is possible for great number of properties including proxy signatures; (partially) blind signatures; verifiably encrypted signatures; undeniable signatures; forward-secure signatures; (strongly) key insulated signatures; online/offline signatures; threshold signatures; and (with some limitations) aggregate signatures. Using well-known results for PKI-based schemes, we conclude that such identity-based signature schemes with additional properties can be constructed, enjoying some better properties than specific schemes proposed until know. In particular, our work implies the existence of identity-based signatures with additional properties that are provably secure in the standard model, do not need bilinear pairings, or can be based on general assumptions.

In this paper, we propose a Directed Threshold Multi-Signature Scheme. In this threshold signature scheme, any malicious set of signers cannot impersonate any other set of signers to forge the signatures. In case of forgery, it is possible to trace the signing set. This threshold signature scheme is applicable when the message is sensitive to the signature receiver; and the signatures are generated by the cooperation of a number of people from a given group of senders.

In a threshold RSA signature scheme, dishonest participants can disrupt signature generation by submitting junk instead of their partial signatures. A threshold signature system is robust if it allows generation of correct signatures for a group of t honest participants, and in the presence of malicious participants. The purpose of this paper is two-fold. First we show that a robust

Mobile Ad Hoc Networks (MANET), due to their lack of physical infrastructures or centralized authorities, pose a number of security challenges to a protocol designer. In particular, several typical application scenarios demand the design of protocols that cannot base their security on the existence of trusted parties or setup information, but rather need to leverage uniquely on assumptions limiting the corrupting power of the adversaries. This naturally defines security design and analysis paradigms similar to those of the Threshold Cryptography area, where it is typically assumed that an adversary can corrupt up to a limited amount of entities or resources. Therefore a secure realization of primitives from Threshold Cryptography in MANET promises to be applicable to several MANET protocols.Recently, in [10], we started the analysis of Threshold Cryptography solutions over MANET, by focusing on the problem of extending to these networks known efficient threshold signature schemes for wired networks. In particular, we noted a major design difficulty due to the lack of full network connectivity that significantly constrained the network topology assumptions under which a MANET threshold signature scheme can be proved secure. In this paper we continue our investigation and present a new MANET threshold signature scheme that is secure under significantly improved topology assumptions. Surprisingly, we break through an apparent barrier due to well-known results from the Distributed Computing area.

In this paper we propose a new designated verifier signature scheme based on the threshold signature scheme presented (8) by Ghodosi and Pieprzyk. The advan- tages of the new scheme compared with previously proposed solutions are its computational efficiency and its simple and rational design that allows distributed implementations of the computations and suits the needs of both single individuals

This paper develops an authentication framework for heterogeneous wireless sensor networks. We Introduce a novel concept, called k-security, in order to thwart the impact of false alerts emanating from malicious sensor nodes. The proposed technique relies on elliptic curve cryptography and threshold signature. The major novelty of our approach is that an intermediate verification of the alert messages allows discarding spoofed messages while being forwarded. This saves important energy and processing resources and consequently extends the network lifetime.

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