Efficient and short certificateless signatures secure against realistic adversaries

The notion of certificateless cryptography is aimed to eliminate the use of certificates in traditional public key cryptography and also to solve the key-escrow problem in identity-based cryptography. Many kinds of security models have been designed for certificateless cryptography and many new schemes have been introduced based on the correspondence of the security models. In generally speaking, a stronger security model can ensure a certificateless cryptosystem with a higher security level, but a realistic model can lead to a more efficient scheme. In this paper, we focus on the efficiency of a certificateless signature (CLS) scheme and introduce an efficient CLS scheme with short signature size. On one hand, the security of the scheme is based on a realistic model. In this model, an adversary is not allowed to get any valid signature under false public keys. On the other hand, our scheme is as efficient as BLS short signature scheme in both communication and computation and, therefore, turns out to be more efficient than other CLS schemes proposed so far. We provide a rigorous security proof of our scheme in the random oracle model. The security of our scheme is based on the k-CAA hard problem and a new discovered hard problem, namely the modified k-CAA problem. Our scheme can be applied to systems where signatures are typed in by human or systems with low-bandwidth channels and/or low-computation power.     

一类高效的无证书代理盲签名方案

已有的代理盲签名方案主要是基于传统公钥密码系统(PKI)以及基于身份的公钥密码系统(ID-PKC)提出的,它们分别存在看证书存储、管理以及密钥托管等问题.为避免上述问题,在无证书公钥密码系统上利用双线性对的知识提出了一种高效的无证书代理盲签名方案,该方案不仅具有较高的效率,满足代理盲签名要求的所有性质,而且克服了它们所...     

几个无证书签名方案的伪造攻击

自2003年Al-Riyami和Paterson首次提出无证书公钥密码体制的概念和第一个无证书签名方案以来,许多无证书签名方案相继被提出。汤永利等提出了9个无双线性对运算的无证书签名方案,并声称这些无证书签名方案在椭圆曲线离散对数困难性假设下可证明是安全的。通过对这些无证书签名方案进行安全性分析后,发现其中的5个可证明安全的无证书签名方案不能抵抗替换公钥攻击,并且这5个无证书签名方案中的3 个签名方案即使在不替换用户公钥的情况下,攻击者也可以利用用户的原始公钥对任意消息伪造出有效的签名。给出了具体的伪造攻击方法,证明了这5个无证书签名方案是不安全的。     

有效的无证书签名方案

为解决基于身份的密码体制的密钥托管问题以及传统公钥密码体制的公钥认证问题,通过修改Barreto等人提出的高效的基于身份的签名方案中的私钥和公钥的产生算法,提出了一个无证书签名方案。该方案在随机预言模型下是可证明安全的,而且也是高效的方案,只需要一个对运算。     

一种无证书的前向安全代理签名方案

结合前向安全性提出一个基于无证书公钥密码体制的代理签名方案。引入密钥更新算法,保证了代理签名方案的前向安全性。当代理签名者的代理密钥泄漏后,攻击者不能伪造当前时段以前的代理签名,从而减小了密钥泄漏所带来的损失。分析结果表明,新方案可避免基于证书密码系统的证书管理问题和基于身份的密钥托管问题。     

An efficient certificateless undeniable signature scheme

Certificateless cryptography addresses the private key escrow problem in identity-based systems, while overcoming the costly issues in traditional public key cryptography. Undeniable signature schemes were proposed with the aim of limiting the public verifiability of ordinary digital signatures. The first certificateless undeniable signature scheme was put forth by Duan. The proposed scheme can be considered as the certificateless version of the identity-based undeniable signature scheme which was introduced by Libert and Quisquater. In this paper, we propose a new scheme which is much more efficient comparing to Duan's scheme. Our scheme requires only one pairing evaluation for signature generation and provides more efficient confirmation and disavowal protocols for both the signer and the verifier. We also prove the security of our scheme in the strong security model based on the intractability of some well-known pairing-based assumptions in the random oracle model.     

具有聚合性质的无证书代理重签名方案

现有的代理重签名大多是基于证书或身份的密码系统,存在证书管理和密钥托管等问题。为了克服已有代理重签名方案的安全性依赖强和计算开销大等缺陷,结合代理重签名和无证书公钥密码体制,设计了一种具有聚合性质的无证书代理重签名方案,可将任意长度集合上的签名或者重签名聚合成一个集合上的签名,有效减少了签名验证的计算代价和通信成本。分析结果表明,新方案具有较短的签名长度和重签名长度,并且在k MCDH假设下是存在性不可伪造的。     

一个新的信息可恢复的无证书签名方案

无证书密码公钥系统的提出,解决了基于身份和基于证书公钥密码系统中的密钥托管问题。结合无证书签名体制的这个优点,基于离散对数和Lein Harn等人的无证书数字签名方案,提出了一个离散对数上的信息可恢复的无证书签名方案。该方案能够抵制密钥托管问题,可以减少传输消息本身所需要的费用,同时能够满足Lein Harn等人无证书签名方案所满足的优点,其安全性和效率都得到了提高。     

A pairing-free certificateless digital multisignature scheme using elliptic curve cryptography

In a digital multisignature scheme, two or more signers are allowed to produce a single signature on a common message, which can be verified by anyone. In the literature, many schemes are available based on the public key infrastructure or identity-based cryptosystem with bilinear pairing and map-to-point (MTP) hash function. The bilinear pairing and the MTP function are time-consuming operations and they need a large super-singular elliptic curve group. Moreover, the cryptosystems based on them are difficult to implement and less efficient for practical use. To the best of our knowledge, certificateless digital multisignature scheme without pairing and MTP hash function has not yet been devised and the same objective has been fulfilled in this paper. Furthermore, we formally prove the security of our scheme in the random oracle model under the assumption that ECDLP is hard.     

Efficient many-to-one authentication with certificateless aggregate signatures

Aggregate signatures allow an efficient algorithm to aggregate n signatures of n distinct messages from n different users into one single signature. The resulting aggregate signature can convince a verifier that the n users did indeed sign the n messages. This feature is very attractive for authentications in bandwidth-limited applications such as reverse multicasts and senor networks. Certificateless public key cryptography enables a similar functionality of public key infrastructure (PKI) and identity (ID) based cryptography without suffering from complicated certificate management in PKI or secret key escrow problem in ID-based cryptography. In this paper, we present a new efficient certificateless aggregate signature scheme which has the advantages of both aggregate signatures and certificateless cryptography. The scheme is proven existentially unforgeable against adaptive chosen-message attacks under the standard computational Diffie–Hellman assumption. Our scheme is also very efficient in both communication and computation and the proposal is practical for many-to-one authentication.     

标准模型下的无证书指定验证者签名方案

提出一种标准模型下无证书的指定验证者签名方案。利用双线性对的性质,结合无证书密码体制与指定验证者数字签名,解决公钥系统中指定验证者签名存在的证书管理问题,实现基于身份的密码体制中指定验证者签名的密钥托管。在标准模型下进行验证,结果表明,该方案在假设CDH问题和CBDH问题中,能抵抗适应性选择消息攻击的存在伪造性。     

没有pairing的无证书公钥签名方案

现有的基于无证书的公钥签名方案都是基于椭圆曲线或者是Tate对的,现提出了一种没有pairing的无证书公钥签名方案。在随机预言模型下,证明了新方案是基于计算Diffie-Hellman问题无证书密文不可伪造性(CL-CUF)安全的。该方案避免了基于公钥证书签名方案中的证书存在问题,消除了基于身份签名方案中的密钥托管问题,且算法简单,便于实际应用。     

一种基于椭圆曲线的轻量级身份认证及密钥协商方案

无证书公钥密码体制不存在用户密钥托管问题,也不需要使用证书,可以解决传统公钥密码体制在应用过程中耗时耗资源都比较多的问题.基于素域上的椭圆曲线加法群,提出了一个无证书的身份认证及密钥协商方案,其主要包括认证协议与核心算法.该方案消除了双线性对运算,完成双向认证只需要两次通信,提高了认证和密钥产生的效率,效率比已有协议提高了至少10％;充分利用椭圆曲线上的点加运算,加快了计算速度,在不考虑网络通信耗时的情况下双向认证及产生共享密钥只需要20ms左右.同时该方案能满足已知会话密钥的通信安全、主密钥的前向保密性、抗密钥泄露后的伪装攻击等安全属性.该方案尤其适合于不活跃网络对象之间的安全通信.     

新的无证书的代理签名方案

已有的代理签名方案,大多是基于证书的密码体制或者基于身份的密码体制提出的,都存在证书的管理问题或密钥的托管问题。基于无证书密码体制的优点,在无证书公钥密码体制的基础上提出了一种新的代理签名方案。分析表明, 该方案不需要证书的管理,也没有密钥的托管问题,满足代理签名所要求的所有性质,且在效率上优于已有的基于身份的代理签名方案。     

Efficient and provably-secure certificateless short signature scheme from bilinear pairings

Certificateless public key cryptography is a recently proposed attractive paradigm which combines advantages of both certificate-based and ID-based public key cryptosystems as it avoids usage of certificates and does not suffer from key escrow. In this paper, we present a certificateless signature (CLS) scheme that is proved to be secure in the random oracle model under the hardness assumptions of k-CAA and Inv-CDHP. Our scheme upholds all desirable properties of previously proposed CLS schemes, and requires general cryptographic hash functions instead of the MapToPoint hash function which is inefficient. Furthermore, our scheme is significantly more efficient than all known CLS schemes, and the size of signatures generated by our scheme is approximate 160 bits, which is the shortest certificateless signatures so far. So it can be used widely, especially in low-bandwidth communication environments.     

A new provably secure certificateless short signature scheme

Certificateless public key cryptography simplifies the complex certificate management in the traditional public key cryptography and resolves the key escrow problem in identity-based cryptography. In 2007, Huang et al. revisited the security models of certificateless signature scheme. They classified adversaries according to their attack power into normal, strong, and super adversaries (ordered by their attack power). Recently, Du and Wen proposed a short certificateless signature scheme and presented that their scheme is secure against the strong adversary in the random oracle model. In this paper, we show that their short signature scheme is insecure against the strong adversary. We then propose a new short certificateless signature scheme which is secure against the super adversary. Our scheme is the first certificateless signature scheme which satisfies both the strongest security level and the shortest signature length.     

一种前向安全的无证书代理签名方案*

为了解决密钥泄露问题,提出一个具有前向安全性的无证书代理签名方案。本方案采用密钥不断更新的方法,保证了代理签名方案的前向安全性,即当代理签名者的代理密钥泄露后,攻击者不能伪造当前时段以前的代理签名,从而减小了密钥泄露所带来的损失。同时本方案采用了无证书公钥密码体制,避免了基于证书密码系统的证书管理问题,解决了基于身份的密钥托管问题。     

无证书的可验证环签名方案

将无证书的密码体制与可验证环签名相结合,提出一个无证书的可验证环签名方案。方案具有环签名的性质,在需要时,真实签名者还可向验证者证明自己的身份。方案基于无证书的密码体制,克服了基于身份的密码体制的密钥托管问题,避免基于证书密码体制的公钥存储和管理问题。     

无证书代理盲签名方案

将代理盲签名和无证书签名方案结合,充分利用二者的优势,提出一种无证书代理盲签名方案。使签名避免了基于证书密码系统的证书管理问题和基于身份的密钥托管问题。并对其安全性给予分析,分析结果表明,该方案同时具有代理盲签名的各项安全性质以及强不可伪造性。