Number Of Signers Research Articles

A quantum threshold signature protocol based on mutual unbiased basis

For the existing quantum threshold signature protocols based on entangled state, it is difficult to prepare quantum resources. Meanwhile, for the quantum threshold signature protocols based on single-particle sequence, it has disadvantages of high computation and communication consumptions. To remedy these shortcomings, in this paper, we proposed a quantum threshold signature protocol based on mutual unbiased basis (MUB). In initialization stage, the message owner Alice prepares a quantum sequence [Formula: see text] with length of [Formula: see text], each single particle in [Formula: see text] is chosen from MUBs. The signature key is generated by Alice using threshold secret-sharing distribution algorithm, the verification key is generated by [Formula: see text] signers via threshold secret-sharing recovery algorithm. In signature generation phase, the signers execute the signature algorithm sequentially until the last signer and then obtain the final signature, next send it to verifier. In signature verification phase, the verifier Ver verifies the original message and the final signature using the verification key. Security analysis shows that the proposed protocol can resist interception-forgery attack, collusion attack and denial attack. Performance analysis shows that the proposed protocol is easier to prepare quantum resources than similar protocols, and has lower communication consumption, especially when the number of signers [Formula: see text] and increase gradually. Finally, the correctness of the proposed protocol is verified by simulation experiment on quantum cloud platform.

Code-based Sequential Aggregate Signature Scheme

This paper proposes the first code-based quantum immune sequential aggregate signature (SAS) scheme and proves the security of the proposed scheme in the random oracle model. Aggregate signature (AS) schemes and sequential aggregate signature schemes allow a group of potential signers to sign different messages respectively, and all the signatures of those users on those messages can be aggregated into a single signature such that the size of the aggregate signature is much smaller than the total size of all individual signatures. Because of the aggregation of many signatures into a single short signature, AS and SAS schemes can reduce bandwidth and save storage; moreover, when a SAS is verified, not only the valid but also the order in which each signer signed can be verified. AS and SAS schemes can be applied to traffic control, banking transaction and military applications. Most of the existing AS and SAS schemes are based either on pairing or Rivest–Shamir–Adleman (RSA), and hence, can be broken by Shor’s quantum algorithm for Integer Factoring Problem (IFP) and Discrete Logarithm Problem (DLP). There are no quantum algorithms to solve syndrome decoding problems. Hence, code-based cryptography is seen as one of the promising candidates for post-quantum cryptography. This paper shows how to construct quantum immune sequential aggregate signatures based on coding theory. Specifically, we construct our scheme with the first code based signature scheme proposed by Courtois, Finiasz and Sendrier (CFS). Compared to the CFS signature scheme without aggregation, the proposed sequential aggregate signature scheme can save about 90% storage when the number of signers is asymptotically large.

A Lightweight Certificateless Aggregation Signature Scheme With Provably Security in the Standard Model

In an aggregate signature scheme, $n$ signatures on $n$ different messages from $n$ users can be combined into a single signature. By verifying the signature, the verifier believes that $n$ users did generate the $n$ corresponding signatures. In the recent decade, numerous certificateless aggregate signature (CLAS) schemes have been introduced. There are two issues with these schemes. First, it was in the random oracles model (ROM) that the security proofs of these schemes were given. ROM is an idealized model. A signature scheme is not necessarily secure in real life even if it has proven to be safe in ROM. Second, the number of hash-to-point operations increases linearly with the number of signers in these schemes, so that are not suited for the computation-constrained devices (such as mobile devices). In this article, a new certificateless signature scheme is constructed. Based on it, a new CLAS scheme is proposed. Under the hypothesis that it is hard to solve a computation Diffie–Hellman problem, two schemes are proved to be secure in the standard model. The CLAS scheme needs only three pairing operations and does not need a hash-to-point operation, taken into account the computation cost, it is more efficient than previous CLAS schemes.

Certificateless Short Aggregate Signature Scheme for Mobile Devices

Today, data is exploding. A large amount of data needs to be processed in a timely and an efficient manner. Aggregate signatures are an efficient and secure way to handle large numbers of digital signatures. In an aggregate signature scheme, $n$ signatures on $n$ messages from $n$ users can be combined into a single signature, which can make anyone believes that the $n$ messages were indeed signed by the $n$ corresponding users. In the recent decade, numerous certificateless aggregate signature (CLAS) schemes have been introduced. In most CLAS schemes currently known, the number of hash-to-point operations and the size of signature increase linearly with the number of signers, so they are not suitable for computing restricted devices, such as mobile devices. In this paper, a new CLAS scheme is constructed, which requires only two pairing operations and the signature contains only one point and state information. It is more efficient than the previous ones and suit for the mobile devices.

Signing Without Reading

Most people sign standard term contracts without reading them. This gives drafters an incentive to insert one-sided, inefficient terms. This problem can be solved directly by giving the drafter a duty to draft efficient terms, or indirectly by giving the signer a duty to read (which may remove the incentive to insert one-sided terms if a sufficient number of signers do read the contract). The problem can also be solved in a more draconian way by holding all standard terms unenforceable, irrespective of whether they are efficient or one-sided. Finally, the problem can be solved through hybrid instruments – for instance, American common law gives the signer a duty to read but intervenes when terms are unconscionable. In this short chapter (written for a forthcoming book of Marciano and Ramello, eds.), I argue that a duty to draft efficient terms is the superior instrument. Doctrinally, this means that unread contracts are best seen as agreements to delegate the drafting task to the party that can do so at least costs, as is the case under German law. Because rational parties will never give one of them a wildcard to insert inefficient terms, standard terms should be enforced only to the extent they are efficient. Moreover, economic logic dictates that it should be upon the drafter to prove that the terms are efficient, rather than upon the signer to prove that they are inefficient.

Fully adaptive attribute-based group signature in standard model

Attribute-based group signatures (ABGS) allow a signer to anonymously prove her membership in a group and her ownership of certain attributes, thus can find many applications where both privacy and authentication are required. In this paper, we present a new construction of ABGS based on Fuchsbauer’s automorphic signatures and the Groth and Sahai’s non-interactive witness-indistinguishable proof system. Compared with other ABGS in the literature, our construction is proved secure against fully adaptive adversaries in the standard model, instead of against selected adversaries in the random oracle model. In addition, it admits any signing policies if they can be described as monotone Boolean formulas, and the size of a signature is independent of the number of signers in the group.

Efficient unrestricted identity-based aggregate signature scheme.

An aggregate signature scheme allows anyone to compress multiple individual signatures from various users into a single compact signature. The main objective of such a scheme is to reduce the costs on storage, communication and computation. However, among existing aggregate signature schemes in the identity-based setting, some of them fail to achieve constant-length aggregate signature or require a large amount of pairing operations which grows linearly with the number of signers, while others have some limitations on the aggregated signatures. The main challenge in building efficient aggregate signature scheme is to compress signatures into a compact, constant-length signature without any restriction. To address the above drawbacks, by using the bilinear pairings, we propose an efficient unrestricted identity-based aggregate signature. Our scheme achieves both full aggregation and constant pairing computation. We prove that our scheme has existential unforgeability under the computational Diffie-Hellman assumption.

Sequential aggregate signatures with lazy verification from trapdoor permutations

Sequential aggregate signature schemes allow n signers, in order, to sign a message each, at a lower total cost than the cost of n individual signatures. We present a sequential aggregate signature scheme based on trapdoor permutations (e.g., RSA). Unlike prior such proposals, our scheme does not require a signer to retrieve the keys of other signers and verify the aggregate-so-far before adding its own signature. Indeed, we do not even require a signer to know the public keys of other signers!Moreover, for applications that require signers to verify the aggregate anyway, our schemes support lazy verification: a signer can add its own signature to an unverified aggregate and forward it along immediately, postponing verification until load permits or the necessary public keys are obtained. This is especially important for applications where signers must access a large, secure, and current cache of public keys in order to verify messages. The price we pay is that our signature grows slightly with the number of signers.We report a technical analysis of our scheme (which is provably secure in the random oracle model), a detailed implementation-level specification, and implementation results based on RSA and OpenSSL. To evaluate the performance of our scheme, we focus on the target application of BGPsec (formerly known as Secure BGP), a protocol designed for securing the global Internet routing system. There is a particular need for lazy verification with BGPsec, since it is run on routers that must process signatures extremely quickly, while being able to access tens of thousands of public keys. We compare our scheme to the algorithms currently proposed for use in BGPsec, and find that our signatures are considerably shorter than nonaggregate RSA (with the same sign and verify times) and have an order of magnitude faster verification than nonaggregate ECDSA, although ECDSA has shorter signatures when the number of signers is small.

Privacy in wireless sensor networks using ring signature

The veracity of a message from a sensor node must be verified in order to avoid a false reaction by the sink. This verification requires the authentication of the source node. The authentication process must also preserve the privacy such that the node and the sensed object are not endangered. In this work, a ring signature was proposed to authenticate the source node while preserving its spatial privacy. However, other nodes as signers and their numbers must be chosen to preclude the possibility of a traffic analysis attack by an adversary. The spatial uncertainty increases with the number of signers but requires larger memory size and communication overhead. This requirement can breach the privacy of the sensed object. To determine the effectiveness of the proposed scheme, the location estimate of a sensor node by an adversary and enhancement in the location uncertainty with a ring signature was evaluated. Using simulation studies, the ring signature was estimated to require approximately four members from the same neighbor region of the source node to sustain the privacy of the node. Furthermore, the ring signature was also determined to have a small overhead and not to adversely affect the performance of the sensor network.

Game-based verification of contract signing protocols with minimal messages

A multi-party contract signing (MPCS) protocol is used for a group of signers to sign a digital contract over a network. We analyse the protocols of Mauw, Radomirović and Torabi Dashti (MRT), using the finite-state model checker Mocha. Mocha allows for the specification of properties in alternating-time temporal logic (ATL) with game semantics, and the model checking problem for ATL requires the computation of winning strategies. This gives us an intuitive interpretation of the verification problem of crucial properties of MPCS protocols. MRT protocols can be generated from minimal message sequences, depending on the number of signers. We discover an attack on fairness in a published MRT protocol with three signers and a general attack on abuse-freeness for all MRT protocols. For both attacks, we present solutions. The abuse-freeness attack leads us to a revision of the methodology to construct an MRT protocol. Following this revised methodology, we design a number of MRT protocols using minimal message sequences for three and four signers, all of whom have been successfully model checked in Mocha.

An Identity Based Aggregate Signature from Pairings

An aggregate signature is a useful digital signature that supports aggregation: Given n signatures on n distinct messages from n distinct users, aggregate signature scheme is possible to aggregate all these signature into a single short signature. This single signature, along with the n original messages will convince any verifier that the n users did indeed sign the n original messages respectively (i.e., for i=1,...,n user i signed message m i ). In this paper, we propose an identity based aggregate signature scheme which requires constant pairing operations in the verification and the size of aggregate signature is independent of the number of signers. We prove that the proposed signature scheme is secure against existential forgery under adaptively chosen message and identity attack in the random oracle model assuming the intractability of the computational Diffie-Hellman problem.

ID-Based Sequential Aggregate Signatures

An aggregate signature provides a method for combining n signatures of n different messages from n different signers into one signature of unit length. The main benefit of such schemes is that they allow bandwidth and computational savings. There exist several trials for the construction of ID-based aggregate signature schemes so far. Unfortunately, the computational complexity and (or) signature length of these schemes grow linearly with the number of signers. This paper focuses on the solution of these problems and proposes a new ID-based sequential aggregate signature scheme based on IB-mRSA. It is compatible with RSA and has the fixed signature length. The security analysis shows that it is secure in the random oracle model with the assumption of classical RSA.

A Secure Structured Multisignature Scheme Based on a Non-commutative Ring Homomorphism

Verifying the signing order is sometimes very important in multisignature schemes. A multisignature scheme in which the signing order can be verified is called structured multisignature scheme and many such schemes have been proposed so far. However, there are not many structured multisignature schemes utilizing an algebraic structure of underlying algebraic operation. Ohmori, Chida, Shizuya and Nishizeki have proposed a structured multisignature scheme by utilizing a non-commutative ring homomorphism. Since their scheme does not fully reflect the structure of signers and its rigorous security analysis is not provided, we construct an improved structured multisignature scheme overcoming these problems by utilizing the non-commutative ring homomorphism in a different way and discuss its rigorous security against various attacks, including signer structure forgery, rogue key attack and attack-0 under the discrete logarithm assumption. As far as we know, the scheme in [30], which does not use non-commutative ring homomorphism, guarantees the most rigorous security but the number of signers is restricted in order to prevent attack-0. In contrast, our scheme overcomes attack-0 by virtue of a ring homomorphism and no restriction is imposed on the number of signers.

An ID-based aggregate signature scheme with constant pairing computations

An aggregate signature scheme allows n signatures on n distinct messages from n distinct users to aggregate a single signature. The main benefit of such schemes is that they allow bandwidth and computational savings. Since Boneh et al.’s aggregate signature scheme from pairings, there exist several trials for constructing ID-based aggregate signature schemes. However, their computational complexity for pairing computations grows linearly with the number of signers. In this paper, we propose an efficient ID-based aggregate signature scheme with constant pairing computations. We also give its security proof in the random oracle model under the Computational Diffie–Hellman assumption.

An Efficient and Scalable Quasi-Aggregate Signature Scheme Based on LFSR Sequences

Aggregate signatures can be a crucial building block for providing scalable authentication of a large number of users in several applications like building efficient certificate chains, authenticating distributed content management systems, and securing path vector routing protocols. Aggregate signatures aim to prevent resources (signature and storage elements, and computation) from growing linearly in the number of signers participating in a network protocol. In this paper, we present an efficient and scalable quasi-aggregate signature scheme, CLFSR, based on third-order linear feedback shift register (cubic LFSR) sequences that can be instantiated using both XTR and GH public key cryptosystems. In the proposed CLFSR construction, signers sign messages sequentially; however, the verfier need not know the order in which messages were signed. The proposed scheme offers constant length signatures, fast signing, aggregation, and verification operations at each node, and requires the least storage elements (public keys needed to verify the signature), compared to any other aggregate signature scheme. To the best of our knowledge, CLFSR is the first aggregate signature scheme to be constructed using LFSR sequences. We believe that the CLFSR signature scheme can be catalytic in improving the processing latency as well as reducing space requirements in building secure, large-scale distributed network protocols. We perform extensive theoretical analysis including correctness and security of CLFSR and also present a performance (computation and communication costs, storage overhead) comparison of the proposed scheme with well-known traditional constructions.

Multisignatures with distinguished signing authorities for sequential and broadcasting architectures

In the multisignature scheme with distinguished signing authorities, each group member is responsible for his own signing of a partial message. Recently, Wu and Hsu proposed the multisignature schemes with distinguished signing authorities for sequential and broadcasting architectures. However, in their schemes, the computational complexity for a verifier to verify the multisignature is dependent on the number of members in the group. It is very time-consuming for a verifier to verify the multisignature when the number of group members increases. In this paper, we propose new multisignature schemes with distinguished signing authorities for sequential and broadcasting architectures. In our methods, the computational complexity for a verifier to verify the multisignature will not be significantly affected by the number of signers in the group G. Hence, the verification time for any multisignature is almost equivalent to that of an individual signature.

Human Rights Workshop

I applaud James Glanz's in-depth study of the shifting landscape of human rights activism in the physics community (“Human rights fades as a cause for scientists,” News Focus, 9 Oct., p. [216][1]), but I take issue with his assessments concerning the implications of a failed human rights workshop scheduled to be held at the March 1998 meeting of the American Physical Society (APS) in Los Angeles. The APS erred in scheduling the workshop in competition with scientific and technical sessions. It should come as no surprise that even human rights activists come to scientific meetings to discuss and examine scientific issues. Thus, the inappropriate scheduling made it difficult for people to commit to the workshop. In addition, it is highly unusual for the APS to ask participants to pre-register for policy forums, and it was our nervousness about asking distinguished invited speakers to risk facing a meager audience that prompted the cancellation. It is not clear to me that the low registration reflects a lack of interest or concern for human rights within the physics community. Perhaps a better measure of this interest is the number of signers (1970) of a petition expressing strong support of the scientific community for our repressed and harassed colleagues in the People's Republic of China. And it is also noteworthy that the APS Committee on International Freedom of Scientists has no paucity of volunteers clamoring to serve. In addition, as many as 200 volunteers serve on the “small committees” that have organized letter-writing campaigns on behalf of imprisoned colleagues and dissidents around the world. I regret that I did not make these points more forcefully in my discussions with Glanz. Nonetheless, he has provided a great service in his balanced and penetrating report of the stresses within our community—especially among our Chinese colleagues. [1]: /lookup/doi/10.1126/science.282.5387.216