Cryptanalysis of the One-Time Proxy Signature Scheme Used in Mobile Agents

We ayptanalyze Kim et. al's one-time proxy signature scheme used in mobileagents, and then a successful forgery is introduced It is showed that a dishonest customer cansuccessfully forge a valid one-time proxy signature by impersonating the stiver Furthermore, he canrequest the server with responsibility for the forged bidding information.

Robust Threshold Guillou-Quisquater Signature Scheme

The deficiencies of the first threshold Guilbu-Quisquater signature schemepresented by Li-San Liu, Cheng-Kang Chu and Wen-Guey Tzeng arc analysiscd at first, and then a newthreshold Guillou-Quisquater signature scheme is presented. The new scheme isunforgeable and robustagainst any adaptive adversary if the base Guillou-Quisquater signature scheme is unforgeable underthe chosen message attack and computing the discrete logarithm modulo a prime is hard This schemecan also achieve optimal resilience. However, the new scheme does not need the assumption that N isthe product of two safe primes. The basie signature scheme underlying the new scheme is exactlyGuillou-Quisqualtr signature scheme, and the additional strong computation assumption introduced bythe first threshold Guillou-Quisquater scheme is weaken.

Efficient Dynamic Threshold Group Signature Scheme Based on Elliptic Curve Cryptosystem

The short secret key characteristic of elliptic curve cryptosystem （ECC） are integrated with the （ t, n ） threshold method to create a practical threshold group signature scheme characterized by simultaneous signing. The scheme not only meets the requirements of anonymity and traceability of group signature but also can withstand Tseng and Wang＇s conspiracy attack. It allows the group manager to add new members and delete old members according to actual application, while the system parameters have a little change. Cryptanalysis result shows that the scheme is efficient and secure.

Threshold Signature Scheme Based on Discrete Logarithm and Quadratic Residue

Digital signature scheme is a very important research field in computer security and modern cryptography. A (k, n) threshold digital signature scheme is proposed by integrating digital signature scheme with Shamir secret sharing scheme. It can realize group-oriented digital signature, and its security is based on the difficulty in computing discrete logarithm and quadratic residue on some special conditions. In this scheme, effective digital signature can not be generated by anyk?1 or fewer legal users, or only by signature executive. In addition, this scheme can identify any legal user who presents incorrect partial digital signature to disrupt correct signature, or any illegal user who forges digital signature. A method of extending this scheme to an Abelian group such as elliptical curve group is also discussed. The extended scheme can provide rapider computing speed and stronger security in the case of using shorter key. Key words threshold scheme - digital signature - discrete logarithm - quadratic residuc - threshold digital signature CLC number TP 309. 7 Foundation item: Supported the National Nature Science Foundation of China, Hubei Province (90104005, 2002 AB0039)Biography: FEI Ru-chun (1964-), male, Ph. D candidate, Associated professor, research direction: information security and cryptography.

Publicly Verifiable Distributed Proxy Blind Signature Scheme

In this present paper, we propose a new proxy blind signature scheme, which is publicly verifiable distributed. The algorithm uses the idea of secret sharing schemes to distribute original signer＇s ability and the power of the proxy signer, and ensure the property of publicly verifiable secret sharing schemes. A new concept ＂verifiable time period＂ is also introduced to reduce the time cost in the period of verifications and increases the efficiency of our scheme.

An Efficient Restrictive Blind Signature Scheme with Applications to Electronic Cash

In this paper, a new restrictive blind signature scheme is proposed. Compared with Brands restrictive blind signature scheme, our scheme is even more restrictive and efficient. And our scheme is proved secure, too. A new withdrawal protocol of electronic cash system is designed by using our restrictive blind signature scheme, which is more efficient than the withdrawal protocol and is more appropriate for adopting pre processing and post processing.

Forward-Secure Blind Signature Schemes Based on the Variants of EIGamal

Due to forward-secure-digital-signature＇s capability of effectively reducing loss caused by exposure of secret keys and significant in-application benefits of blind signature aiming at protecting senders＇ privacy, they have been hot spots for decades in the field of cryptography. Illuminated by the integration of forward secure digital signature and blind signature, based on the variants of E1Gamal and assumption of difficulty in solving the discrete logarithm problem in galois field, a forward-secure weak blind signature scheme and a forward-secure strong blind signature scheme are proposed and their security is analyzed thoroughly in this paper. It turns out that forward security, blindness and aptitude of resisting forging attack demonstrated by these two schemes benefit a lot theoretically and practically.

Identity-based Verifiably Committed Signature Scheme without Random Oracles

An identity-based verifiably committed signature scheme (IB-VCS) was proposed, which is proved secure in the standard model (i.e., without random oracles). It enjoys the setup-free property and stand-alone property, both of which make an exchange protocol more practical. The scheme is unconditionally secure against the cheating signer, its security against the cheating verifier is reduced to the computational Diffie-Hellman (CDH) problem in the underlying group, it is secure against the cheating trusted third party if the underlying Paterson Schuldt's identity based signature (IBS) scheme is secure, which is proven true based on the CDH assumption in the standard model.

Traceable ring signature schemes based on SM2 digital signature algorithm and its applications in the data sharing scheme

1 Introduction Identity privacy concerns hinder data sharing by casting doubt on the safeguarding of personal information,eroding trust,and impeding the willingness of individuals and organizations to exchange their data[1,2].The traceable ring signatures(TRSs)addresses the contradiction between identity privacy and regulation[3],no scheme has been developed thus far that is based on SM2,the Chinese cryptographic public key algorithm standard,without relying on centralized trust.

A THRESHOLD BLIND SIGNATURE FROM WEIL PAIRING ON ELLIPTIC CURVES

The idea behind a (t, n) threshold blind signature is that a user can ask at least t out of n players of a group to cooperate to generate a signature for a message without revealing its content. This paper first presents a new blind signature scheme from Weil pairing on elliptic curves. Based on this scheme, a threshold blind signature scheme is proposed. It is efficient and has the security properties of robustness and unforgeability. In the proposed scheme, the group manger is introduced to take the role of distributing the group secret key to each player. However, he cannot forge the players to generate partial blind signatures (Each partial blind signature depends on not only the secret key of the player, but also a random number the player picks). Compared with a threshold signature with a trusted third party, its advantage is obvious; Compared with a threshold signature without a trusted third party, it is more simple and efficient.

Group Signature Based on Non-interactive Zero-Knowledge Proofs

Non-Interactive Zero-Knowledge(NIZK for short) proofs are fascinating and extremely useful in many security protocols. In this paper,a new group signature scheme,decisional linear assumption group signature(DLAGS for short) with NIZK proofs is proposed which can prove and sign the multiple values rather than individual bits based on DLIN assumption. DLAGS does not need to interact between the verifier and issuer,which can decrease the communication times and storage cost compared with the existing interactive group signature schemes. We prove and sign the blocks of messages instead of limiting the proved message to only one bit(0 or 1) in the conventional non-interactive zero-knowledge proof system,and we also prove that our scheme satisfy the property of anonymity,unlinkability and traceability. Finally,our scheme is compared with the other scheme(Benoitt's scheme) which is also based on the NIZK proofs system and the DLIN assumption,and the results show that our scheme requires fewer members of groups and computational times.

Merkle Tree Digital Signature and Trusted Computing Platform

Lack of efficiency in the initial key generation process is a serious shortcoming of Merkle tree signature scheme with a large number of possible signatures. Based on two kinds of Merkle trees, a new tree type signature scheme is constructed, and it is provably existentially unforgeable under adaptive chosen message attack. By decentralizing the initial key generation process of the original scheme within the signature process, a large Merkle tree with 6.87×10^10 possible signatures can be initialized in 590 milliseconds. Storing some small Merkle trees in hard disk and memory can speed up Merkle tree signature scheme. Mekle tree signature schemes are fit for trusted computing platform in most scenarios.

An Efficient Threshold Blind Signature from Weil Pairing

Threshold blind signature is playing an important role in cryptography as well as in practical applications such as e-cash and e-voting systems, etc. In this paper, we present an efficient and practical threshold bind signature from Weil pairing on super-singular elliptic curves or hyper-elliptic curves over finite field and prove that our scheme is provably secure in the random oracle model.

APPLICATION OF ID-BASED AGGREGATE SIGNATURE IN MANETS

Aggregate signatures are a useful primitive which allows aggregating many signatures on different messages computed by different users into a single and constant-length signature and adapts to Mobile Ad hoc NETwork (MANETs) very much. Jumin Song, et al. presented an ID-based aggregate signature, applied it to MANETs and proposed a secure routing scheme. In this work, we analyze Jumin Song, et al.’s aggregate signature scheme and find some limitations on its batch verification. In addition, in this work, we apply Craig Gentry, et al.’s ID-based aggregate signature to on-demand routing pro-tocol to present a secure routing scheme. Our scheme not only provides sound authentication and a secure routing protocol in ad hoc networks, but also meets the nature of MANETs.

Short Group Signatures with Efficient Concurrent Join

Group signature schemes are fundamental cryptographic tools. A group signature scheme allows members of a group to anonymously sign misuse, the anonymity messages. To counter can be revoked by the group manager. The group joining operation is a critical component of group signature scheme, the framing attack can be prevented by group joining processes. This paper presents an efficient group signature scheme with a simple joining protocol that is based on a ＂single message and signature response＂ interaction between the prospective user and the group manager. The security of our group signature is based on the Discrete Logarithm assumption and Decisional Linear Diffie- Hellman assumption. The formal security proof of our scheme is given in the random oracle model. Our scheme is also a very efficient short group signature scheme with efficient concurrent join.

Polar-BBCRSsig:一个基于极化码的数字签名算法

传统公钥密码体制受到量子计算的严重威胁,基于编码的密码体制是抗量子攻击的重要技术之一,然而大多数基于编码的密码方案都存在公钥尺寸过大的问题,严重影响其效率。为此,在基于校验子译码的数字签名算法框架下,采用极化码(Polar码)作为私钥编码,结合非置换等价的陷门设计方法,提出了一个新的基于编码的数字签名算法。这个数字签名算法对自适应选择消息攻击是存在不可伪造的,且在同等安全级别下对比同类方案具有更小的公钥尺寸。

基于门限签名的时间轮换公证人组模型研究

随着各类区块链系统的不断涌现,跨链交互需求不断增加,跨链桥验证环节的安全性显得愈发重要。公证人机制原理简单、效率较高,常用于跨链交易验证、跨链交易确认等环节。但公证人机制存在去中心化程度低、低签名比例可验证交易、验证节点信息公开等问题。为提高跨链桥验证环节的安全性,提出了一种基于门限签名的时间轮换公证人组模型。该模型中的公证人组由同时拥有源区块链和目标区块链账户的高信用值节点组成。公证人组中的验证节点有任期要求且需质押保证金,公证人组采用门限签名技术对跨链交易进行签名,一半以上的验证节点签名后,跨链交易才能实施;候选公证人组为时间轮换公证人组提供新验证节点。分析结果表明,所提模型去中心化程度高,验证节点恶意攻击率低,验证签名环节安全性高,验证节点私密性高,跨链消息验证效率高。

车联网中支持直接撤销的外包属性签名方案

数字签名在应对车联网中数据窜改威胁时扮演着重要作用,然而现有的签名方案在灵活性、效率、隐私保护、用户密钥管理等方面存在诸多问题,难以在车联网中释放其潜力。针对这些问题,提出了一个面向车联网的直接可撤销外包属性签名方案。该方案使用了基于线性秘密分享的签名策略机制,赋予车联网用户在签名生成和验证方面的灵活性和隐私保护。此外,设计了一种高效的用户密钥直接撤销机制,以提供对用户的实时撤权。所提方案还构造了一种外包验证方法,从而显著降低了验证者的计算和存储开销。安全性分析结果表明,所提方案在选择消息攻击下具有不可伪造性,并且能够抵抗合谋攻击。实验结果表明了该方案相较于其他方案的优势及其在车联网中的实用性。

基于SM2的强前向安全性两方共同签名方案

现存SM2数字签名研究已不能满足长期使用主私钥的安全。为更好保证成员私钥安全,结合两方共同签名与SM2算法,在现存方案的基础上加入强前向安全性,无可信中心,可避免可信中心权威欺诈与长期使用主私钥被窃取问题。该方案具有3个特点:前向安全性、后向安全性、无可信中心。方案需要两轮通信,线上两方各需要一次标量乘,保持高效率不变的同时,使得攻击者难以窃取成员密钥,更好保证成员长期使用密钥的安全性。

A NEW ANONYMITY CONTROLLED E-CASH SCHEME

E-cash is a type of very important electronic payment systems. The complete anonymity of E-cash can be used for criminal activities, so E-cash should be anonymity controlled.Moreover, Elliptic Curve Cryptography(ECC) has been regard as the mainstream of current public cryptography . In this paper, a new anonymity controlled E-cash scheme based on ECC for the first time and using a new technology-one-time key pairs digital signature is designed, and its security and efficiency are analyzed. In our scheme, the coin tracing and owner tracing can be implemented.