Multi-proxy quantum group signature scheme with threshold shared verification

A multi-proxy quantum group signature scheme with threshold shared verification is proposed. An original signer may authorize a proxy group as his proxy agent. Then only the cooperation of all the signers in the proxy group can generate the proxy signature on behalf of the original signer. In the scheme, any t or more of n receivers can verify the message and any t - 1 or fewer receivers cannot verify the validity of the proxy signature.

A NEW THRESHOLD MULTI-PROXY MULTI-SIGNATURE SCHEME

This paper proposes a threshold mult-proxy multi-signature scheme with share verification. In the scheme, a subset of original signers allows a designated group of proxy signers to sign on behalf of the original group. A message m has to be signed by a subset of proxy signers who can represent the proxy group. Then, the proxy signature is sent to the verifier group. A subset of verifiers in the verifier group can also represent the group to authenticate the proxy signature. In other words, some threshold values will be given to indicate the number of persons to represent a group to authorize the signing capability or to sign a message or to verify the proxy signature.

CONSTRUCTION OF PROXY BLIND SIGNATURE SCHEME BASED ON MULTI-LINEAR TRANSFORM

A general method of constructing proxy blind signature is proposed based on multilinear transform. Based on this method, the four proxy blind signature schemes are correspondently generated with four different signature equations, and each of them has four forms of variations of signs. Hence there are sixteen signatures in all, and all of them are proxy stronglyblind signature schemes. Furthermore, the two degenerated situations of multi-linear transform are discussed. Their corresponding proxy blind signature schemes are shown, too. But some schemes come from one of these degenerate situations are proxy weakly-blind signature scheme.The security for proposed scheme is analyzed in details. The results indicate that these signature schemes have many good properties such as unforgeability, distinguish-ability of proxy signature,non-repudiation and extensive value of application etc.

A New ID-Based Proxy Multi-Signature Scheme from Bilinear Pairings

ID-based public key cryptosystem can be a good alternative for certifieate-based public key setting. This paper provides an efficient ID-based proxy multi signature scheme from pairings. In the random oracle model, we prove that our new scheme is secure against existential delegation forgery with the assumption that Hess＇s scheme-1 is existential unforgeable, and that our new scheme is secure against existential proxy multi-signature forgery under the hardness assumption of the computational Diffie-Hellman problem.

SECURITY ANALYSIS AND IMPROVEMENT OF A NEW THRESHOLD MULTI-PROXY MULTI-SIGNATURE SCHEME

Kang, et al. [Journal of Electronics(China), 23(2006)4] proposed a threshold multi-proxy multi-signature scheme, and claimed the scheme satisfies the security requirements of threshold multi-proxy multi-signature. However, in this paper, two forgery attacks are proposed to show that their schemes have serious security flaws. To overcome theses flaws, an improvement on Kang, et al.’s scheme is proposed.

IMPROVEMENT OF NONREPUDIABLE THRESHOLD MULTI-PROXY THRESHOLD MULTI-SIGNATURE SCHEME WITH SHARED VERIFICATION

In 2005, Bao, et al. [Appl. Math. and Comput., vol.169, No.2, 2005] showed that Tzeng, et al.’s nonrepudiable threshold multi-proxy multi-signature scheme with shared verification was insecure, and proposed an improved scheme with no Share Distribution Center (SDC). This paper shows that Bao, et al.’s scheme suffers from the proxy relationship inversion attack and forgery attack, and pro- poses an improvement of Bao, et al.’s scheme.

A Nominative Multi-Proxy Signature Scheme Based on ECC

A nominative multi-proxy signature in which the original signer authorizes a group of proxy signers is presented. Meanwhile, our proposed scheme is based on elliptic curve cryptosystem which is more efficient than the corresponding one based on traditional discrete logarithm.

A NEW MULTI-PROXY SIGNATURE FROM BILINEAR PAIRING

Proxy signatures are very useful tools when one needs to delegate his/her signing capability to other parties. In this paper,a new multi-proxy signature scheme is proposed. The new scheme is constructed from bilinear pairings using Boneh,Lynn,and Shacham’s (BLS) short signatures. The proxy key for the proxy group is just a short signature on the proxy warrant generated by the original signer. Due to the use of short signatures,our scheme is not only efficient,but also satisfies all the security requirements of the strong proxy signature.

Provable Security of ID-Based Proxy Multi-Signature Schemes

In the last couple of years, D-based cryptography has got fruitful achievements. Proxy multi-signature allows a designated person, called a proxy signer, to sign on behalf of two or more original signers. In this paper, we present a general security model for ID-based proxy multi-signature （ID-PMS） schemes. Then, we show how to construct a secure ID-PMS scheme from a secure ID-based signature scheme, and prove that the security of the construction can be reduced to the security of the original ID-based signature scheme.

Improvement of M-U-O and K-P-W proxy signature schemes

The concept of proxy signature introduced by Mambo, Usuda, and Okamoto allows a designated person, called a proxy signer, to sign on behalf of an original signer in 1996. However, most existing proxy signature schemes does not support nonrepudiation. In this paper, we propose two secure nonrepudiable proxy signature schemes, which overcome disadvantages of M U O and K P W proxy signature schemes, respectively. The schemes proposed can withstand public key substitution attack and forge attack. In addition, our new schemes have some other advantages such as proxy signature key generation and updating using insecure channels. Our approach can also be applied to other ElGamal like proxy signature schemes.

A SECURE PROXY SIGNATURE SCHEME BASED ON ELLIPTIC CURVE CRYPTOSYSTEM

Proxy signature is a special digital signature which enables a proxy signer to sign messages on behalf of the original signer. This paper proposes a strongly secure proxy signature scheme and a secure multi-proxy signature scheme based on elliptic curve cryptosystem. Contrast with universal proxy signature schemes, they are secure against key substitute attack even if there is not a certificate authority in the system, and also secure against the original signer's forgery attack. Furthermore, based on the elliptic curve cryptosystem, they are more efficient and have smaller key size than other system. They can be used in electronics transaction and mobile agent environment.

Improved certificateless multi-proxy signature

Multi-proxy signature is a scheme that an original signer delegates his or her signing capability to a proxy group. In the scheme, only the cooperation of all proxy signers in the proxy group can create a signature on behalf of the original signer. Jin and Wen firstly defined the formal security model of certificateless multi-proxy signature （CLMPS） and proposed a concrete CLMPS scheme. However, their construction model is inaccurate, the concrete signature scheme has has three problems： the definition of the strengthened security a security flaw, and the proof of the security is imperfect. With further consideration, a remedial strengthened security model is redefined, and an improved scheme is also proposed, which is existentially unforgeable against adaptively chosen-warrant, chosen-message and chosen-identity attacks in the random oracles. In this condition, the computational Diffie-Hellman （CDH） assumption is used to prove full security for our CLMPS scheme.

A Quantum Multi-Proxy Blind Signature Scheme Based on Entangled Four-Qubit Cluster State

In this paper, a multi-proxy blind signature scheme based on controlled quantum teleportation is proposed.Entangled four-qubit Cluster state functions as quantum channel, which needs less resource to complete the quantum multi-proxy blind signature. The scheme uses the physical characteristics of quantum mechanics to guarantee its blindness, unforgeability, and undeniability. The eavesdropping check is used to ensure the security. Our scheme has a foreseeable application to the E-business, E-governments, and etc.

An Improved Proxy Multi-Signature Scheme

Based on the Kim-like's proxy multi-signature scheme, an improved proxymulti-signature scheme is proposed. The new scheme overcomes the two problems in the Kim-like'sproxy multi-signature scheme: (1) Security issue ( every original signer can forge a valid proxymulti-signature for any message); (2) Efficiency issue ( both the size of the proxy multi-signatureand the efficiency of signature checking are dependent on the number of the original signers).

Self-certified multi-proxy signature schemes with message recovery

Multi-proxy signature schemes allow the original signer to delegate his/her signing power to n proxy signers such that all proxy signers must corporately generate a valid proxy signature on behalf of the original signer. We first propose a multi-proxy signature scheme based on discrete logarithms and then adapt it to the elliptic curve cryptosystem. With the integration of self-certified public-key systems and the message recovery signature schemes,our proposed schemes have the following advan-tages:(1) They do not require the signing message to be transmitted,since the verifier can recover it from the signature;(2) The authentication of the public keys,verification of the signature,and recovery of the message can be simultaneously carried out in a single logical step;(3) No certificate is needed for validating the public keys. Further,the elliptic curve variant with short key lengths especially suits the cryptographic applications with limited computing power and storage space,e.g.,smart cards. As compared with the previous work that was implemented with the certificate-based public-key systems,the proposed schemes give better performance in terms of communication bandwidth and computation efforts.

A Practical E-Payment Protocol Based on Quantum Multi-Proxy Blind Signature

A practical E-payment protocol is presented in this paper. It is based on quantum multi-proxy blind signature. Adopting the techniques of quantum key distribution, one-time pad and quantum multi-proxy blind signature, our E-payment system could protect user's anonymity as the traditional E-payment systems do, and also have unconditional security, which the classical E-payment systems can not provide. Furthermore, compared with the existing quantum E-payment systems, this practical system could not only support mobile E-payment transactions but also inter-bank transactions.

Efficient ID-based proxy multi-signature scheme secure in random oracle

Proxy signature schemes enable an entity to del- egate its signing rights to any other party, called proxy signer. As a variant of proxy signature primitive, proxy multi- signature allows a group of original signers to delegate their signing capabilities to a single proxy signer in such a way that the proxy signer can sign a message on behalf of the group of original signers. We propose a concrete ID-based proxy multi-signature scheme from bilinear pairings. The proposed scheme is existential unforgeable against adaptively chosen message and given ID-attack in random oracle model under the computational Diltie-Hellman （CDH） assumption. The fascinating property of new scheme is that the size of a proxy multi-signature is independent of the number of original sign- ers. Furthermore the proposed scheme is simple and com- putationally more efficient than other ID-based proxy multi- signature schemes.

A secure threshold Paillier proxy signature scheme

As e-commerce applications and the underlying public key infrastructure have become more popular over time,many digital mechanisms emulating traditional business activities have been developed and deployed. To build a full-fledgedsecure digital world,secure implementations of more commercial activity primitives are required. In this paper,we present asecure proxy signature scheme and its threshold version based on the homomorphic Paillier cryptosystem,which can be used inmany e-commerce applications such as e-voting,e-bidding/auction,and privacy-preserving data mining. These two schemes areexistentially unforgeable against chosen-message attacks and chosen-warrant attacks in the random oracle model. Although it isbased on factoring,the threshold Paillier proxy scheme operates without requiring any trusted dealer or combiner. Thus,these twoschemes are practical for integration in modularized secure multi-party protocols.

基于Nyberg-Rueppel签名体制的盲代理多重签名方案

为了实现一个盲代理签名能够同时代表多个原始签名人签名,在对盲代理签名研究的基础上,首次提出了盲代理多重签名这一概念,该签名克服了一个盲代理签名只能代表一个原始签名人签名的局限性。此外,在Nyberg-Rueppel盲代理签名和代理多重签名2种体制研究的基础上,基于离散对数,分别提出了具有盲代理签名和代理多重签名双重性质的第一类盲代理多重签名方案和第二类盲代理多重签名方案,并对2方案的安全性进行了论证。

Hwang-多重代理多重签名方案的改进

多重代理多重签名就是由多个人组成的原始签名者组授权由多个人组成的代理签名者组对消息进行签名.通过对Hwang-多重代理多重签名方案的研究,发现了它的弱点,即可伪造对任意消息的签名.对此提出了改进方案,并详细分析了其安全性.改进后方案可抵抗现在已知的攻击,更加完善.