80 research outputs found

    Review on multisignature schemes based upon DLP

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    In digital signature schemes a user is allowed to sign a document by using a public key infrastructure (PKI). For signing a document, the sender encrypts the hash of the document by using his private key. Then, the verifier uses the signer’s public key to decrypt the received signature and to check if it matches the document hash. Generally a digital signature scheme demands only one signer to sign a message so that the validity of the signature can be checked later. But under some situations a group of signers is required to sign a message cooperatively, so that a single verifier or a group of verifiers can check the validity of the given signature. This scheme is known as a multisignature. A multisignature scheme is one of the tools in which plural entities can sign a document more efficiently than they realize it by trivially constructing single signatures. In general, in a multisignature scheme, the total signature size and the verification cost are smaller than those in the trivially constructed scheme. Thus, plural signers can collectively and efficiently sign an identical message. There are different base primitives describing the type of numerical problems upon which the underlying security scheme is based on. In this thesis, some of the most important DLP based multisignature schemes are presented. A categorization between these different existing schemes has been shown, along with their pros and cons

    SECURE AND EFFICIENT DECENTRALIZED GROUP KEY ESTABLISHMENT REVISED ELGAMAL PROTOCOL FOR GROUP COMMUNICATION

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    in distributed system it is sometimes necessary for users to share the power to use a cryptosystem. The system secret is divided up into shares and securely stored by the entities forming the distributed cryptosystem. We propose a new Multi signature scheme without a trusted third party (TTP), based on a round optimal, publicly verifiable distributed key generation (DKG) protocol. In this propose system, we define a new propose ElGamal algorithm, in that ElGamal algorithm has two random numbers. The origina l ElGamal algorithm is that, it has only one random number. In order to improve its security, the proposed scheme adds one more random number. The security of the proposed signature scheme is the same with the ElGamal sig nature scheme which is based on the difficult computable nature of discrete logarithm over finite fields. In this paper, the algorithm is proposed to enhance the security and usage of more random number to make algorithm more complicate d, which can also make the link between the random number and the key more complicated. The scheme presented in this paper after analysis showed that the security level is kept high by using two random numbers and the time complex ity is reduced

    多人数署名の証明可能安全性に関する研究

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    筑波大学 (University of Tsukuba)201

    Secure Mobile Agents in Electronic Commerce by Using Undetachable Signatures from Pairings

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    It is expect that mobile agents technology will bring significant benefits to electronic commerce. But security issues, especially threats from malicious hosts, become a great obstacle of widespread deployment of applications in electronic commerce based on mobile agents technology. Undetachable digital signature is a category of digital signatures to secure mobile agents against malicious hosts. An undetachable signature scheme by using encrypted functions from bilinear pairings was proposed in this paper. The security of this scheme base on the computational intractability of discrete logarithm problem and computational Diffe-Hellman problem on gap Diffle-Hellman group. Furthermore, the scheme satisfies all the requirements of a strong non-designated proxy signature i.e. verifiability, strong unforgeability, strong identifiability, strong undeniability and preventions of misuse. An undetachable threshold signature scheme that enable the customer to provide n mobile agents with ‘shares’ of the undetachable signature function is also provided. It is able to provide more reliability than classical undetachable signatures

    Security in Wireless Medical Networks

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    How to Prove Schnorr Assuming Schnorr: Security of Multi- and Threshold Signatures

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    This work investigates efficient multi-party signature schemes in the discrete logarithm setting. We focus on a concurrent model, in which an arbitrary number of signing sessions may occur in parallel. Our primary contributions are: (1) a modular framework for proving the security of Schnorr multisignature and threshold signature schemes, (2) an optimization of the two-round threshold signature scheme FROST\mathsf{FROST} that we call FROST2\mathsf{FROST2}, and (3) the application of our framework to prove the security of FROST2\mathsf{FROST2} as well as a range of other multi-party schemes. We begin by demonstrating that our framework is applicable to multisignatures. We prove the security of a variant of the two-round MuSig2\mathsf{MuSig2} scheme with proofs of possession and a three-round multisignature SimpleMuSig\mathsf{SimpleMuSig}. We introduce a novel three-round threshold signature SimpleTSig\mathsf{SimpleTSig} and propose an optimization to the two-round FROST\mathsf{FROST} threshold scheme that we call FROST2\mathsf{FROST2}. FROST2\mathsf{FROST2} reduces the number of scalar multiplications required during signing from linear in the number of signers to constant. We apply our framework to prove the security of FROST2\mathsf{FROST2} under the one-more discrete logarithm assumption and SimpleTSig\mathsf{SimpleTSig} under the discrete logarithm assumption in the programmable random oracle model

    Identity-based threshold group signature scheme based on multiple hard number theoretic problems

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    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 individual hard problem. 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

    Blind multi-signature scheme based on factoring and discrete logarithm problem

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    One of the important objectives of information security systems is providing authentication of the electronic documents and messages. In that, blind signature schemes are an important solution to protect the privacy of users in security electronic transactions by highlighting the anonymity of participating parties. Many studies have focused on blind signature schemes, however, most of the studied schemes are based on single computationally difficult problem. Also digital signature schemes from two difficult problems were proposed but the fact is that only finding solution to single hard problem then these digital signature schemes are breakable. In this paper, we propose a new signature schemes base on the combination of the RSA and Schnorr signature schemes which are based on two hard problems: IFP and DLP. Then expanding to propose a single blind signature scheme, a blind multi-signature scheme, which are based on new baseline schemes
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