48 research outputs found

    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

    Security Analysis of the Unrestricted Identity-Based Aggregate Signature Scheme

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    Aggregate signatures allow anyone to combine different signatures signed by different signers on different messages into a single short signature. An ideal aggregate signature scheme is an identity-based aggregate signature (IBAS) scheme that supports full aggregation since it can reduce the total transmitted data by using an identity string as a public key and anyone can freely aggregate different signatures. Constructing a secure IBAS scheme that supports full aggregation in bilinear maps is an important open problem. Recently, Yuan {\it et al.} proposed an IBAS scheme with full aggregation in bilinear maps and claimed its security in the random oracle model under the computational Diffie-Hellman assumption. In this paper, we show that there exists an efficient forgery attacker on their IBAS scheme and their security proof has a serious flaw.Comment: 9 page

    EFFICIENT AND SCALABLE NETWORK SECURITY PROTOCOLS BASED ON LFSR SEQUENCES

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    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

    A Genuine Random Sequential Multi-signature Scheme

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    The usual sequential multi-signature scheme allows the multi-signers to sign the document with their own information and sequence, and the signature is not real random and secure. The paper analyzes the reasons for the insecurity of the previous multi-signature scheme, and puts forward a Genuine Random Sequential Multi-signature Scheme based on The Waters signature scheme, and the experiment proves that this scheme is a good scheme suitable for the practical application with high computing efficiency

    A Genuine Random Sequential Multi-signature Scheme

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    The usual sequential multi-signature scheme allows the multi-signers to sign the document with their own information and sequence, and the signature is not real random and secure. The paper analyzes the reasons for the insecurity of the previous multi-signature scheme, and puts forward a Genuine Random Sequential Multi-signature Scheme based on The Waters signature scheme, and the experiment proves that this scheme is a good scheme suitable for the practical application with high computing efficiency

    An identity based routing path verification scheme for wireless sensor networks

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    Deterministic Identity Based Signature Scheme and its Application for Aggregate Signatures

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    The revolutionary impact offered by identity based cryptography is phenomenal. This novel mechanism was first coined by Adi Shamir in 1984. Since then, several identity based signature schemes were reported. But surprisingly, none of the identity based signature scheme is having the property of determinism and does rely on bilinear pairing. We think positively in answering this long standing question of realizing deterministic identity based signature in composite order groups and we succeed in developing a signature scheme based on RSA assumption and is deterministic. It is indeed helpful in devising variants of signature primitive. Fully aggregateable identity based signature schemes without prior communication between the signing parties is an interesting issue in identity based cryptography. It is easy to see that deterministic identity based signature schemes lead to full aggregation of signatures without the aforementioned overhead. The major contribution of this paper is a novel deterministic identity based signature scheme whose security relies on the strong RSA assumption and random oracles. Based on this newly proposed deterministic identity based signature scheme, we design an identity based aggregate signature scheme which achieves full aggregation in one round. We formally prove the schemes to be existentially unforgeable under adaptive chosen message and identity attack
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