Secure and efficient anonymous proxy signature scheme in the random oracle model

Anonymous proxy signature scheme can provide the privacy protection for the proxy signer. Recently, Yu et al. proposed an anonymous proxy signature, which can be viewed as the organic combination of proxy signature and ring signature. However, the efficiency is low. In this paper, we propose an efficient and secure proxy signature with the properties of anonymity and traceability, and it is provably secure in the random oracle model. Compared with Yu et al.＇s scheme, the scheme has higher efficiency.

一种基于国密算法的区块链无证书加密机制

区块链因具有分布式、不可篡改和不变性的特点而广受关注,但区块链中使用的国际密码算法存在一定的后门安全隐患。现基于国密算法SM2,结合无证书密码机制,提出了一种基于区块链的无证书公钥加密(Certificateless Public Key Encryption,CL-PKE)方案。该方案不依赖双线性配对,降低了计算成本,消除了证书管理和密钥托管问题,并且利用区块链不可篡改和可追溯的优点,实现了用户对公钥的更新与撤销,同时能够对抗无证书机制中的Type-1和Type-2型敌手。该方案基于计算性Diffie-Hellman问题(Computational Diffie-Hellman Problem,CDHP)的困难性,在随机预言模型中被证明在自适应选择密文攻击下具有不可区分性。最后进行性能分析与测试,结果表明,与现有CL-PKE方案相比,该方案的计算效率至少提升11%。

一种基于格理论的盲签名方案

量子计算机的发展使得传统公钥加密系统不再具有足够的安全性,研究抗量子的签名方案迫在眉睫,而格基签名可以满足这一需要。数字货币系统的出现使得盲签名得到了更多的关注,主要应用于匿名认证、电子投票等。通过对qTESLA方案以及RBS方案的研究和分析,给出一个基于格的盲签名方案,安全性基于RLWE问题以及RSIS问题的困难性,并证明了方案的盲性和one-more不可伪造性。

适用于现场总线的无证书聚合签名方案

针对现场总线缺乏身份认证以及设备计算资源和网络带宽受限的缺点,提出一种适用于现场总线网络的无证书聚合签名方案,避免复杂的证书管理和密钥管理,在注册阶段使用中国剩余定理,提高假名分发的效率。在安全性证明部分,利用分叉引理对所提签名方案的不可伪造性进行证明。效率方面,签名生成和签名验证阶段避免计算量较大的双线性对运算,支持聚合签名,实现对签名的批量认证,适用于对实时性要求较高且计算资源受限的现场总线网络。实验结果表明,该方案相比于其它方案,计算开销和通信开销有显著降低。

基于边缘计算的并行密钥隔离聚合签名方案

无线医疗传感器网络的出现为患者的治疗带来了极大的便利.但是,无线医疗传感器网络中往往都使用不可信的公共信道进行数据通信并且只有唯一的云服务器处理大量的医疗数据,这就导致了通信安全、隐私保护、密钥泄露、云服务器计算负担过大、延迟高等问题.此外,现有的大多数无证书聚合签名方案无法抵抗完全选择密钥攻击.针对上述问题,本文提出一种适用于无线医疗传感器网络基于边缘计算的无证书并行密钥隔离聚合签名方案.方案引入边缘计算的架构使得签名的验证和聚合过程在更靠近终端用户的边缘层进行,在降低中心云服务器计算负担的同时还能有效的保护患者的隐私.本文方案继承了无证书和密钥隔离技术的优点,同时避免了复杂的证书管理、密钥托管以及密钥暴露等问题.在随机预言模型下证明了本文方案可以抵抗完全选择密钥攻击、Type I攻击以及Type II攻击.性能分析表明,与相关无证书签名方案相比,本文方案的计算开销至少可降低74.03%,通信开销至少可降低25%.

基于SM2的高效签密方案

签密融合了数字签名和数据加密的功能,能有效减少系统的计算开销和通信开销.现有签密方案主要以国外设计为主,不符合核心技术自主创新、信息安全自主可控的要求.包含数字签名算法、数据加密算法的SM2密码算法是我国自主设计的商用密码算法,同等安全强度下,计算效率和传输效率均较高,已成为我国密码行业标准,广泛应用于各个领域,以保护数据安全.基于SM2密码算法的核心技术,提出首个基于SM2的高效签密方案.方案具有定长的系统公开参数、用户公私钥对,其中用户私钥由1个整数组成,公钥由1个群元素构成,密文由1个群元素和n比特组成(n为签名数据与明文长度之和).方案的安全性基于椭圆曲线上的离散对数和ECDH困难问题假设.在随机预言模型中证明了方案的安全性.理论分析与实验仿真均表明,相较于传统的先签名再加密的处理方式,方案的通信效率和计算效率都有一定的优势,具有实用价值.

支持商密SM9算法框架的多因素认证方案

无线传感器技术使用公开无线信道且存储和计算资源受限,这使其容易遭受潜在的主动攻击(篡改等)和被动攻击(监听等)。身份认证是保障信息系统安全的第一道防线,如何为无线传感器设备设计多因素认证方案是目前安全协议研究的热点。目前,大多数身份认证方案都基于国外密码标准设计,不符合国家核心技术自主可控的网络空间安全发展战略。商密SM9标识密码算法是中国密码标准,已由ISO/IEC标准化并被广泛使用。因此,该文研究如何在商密SM9标识密码算法框架下,将口令、生物特征以及智能卡相结合来设计多因素身份认证方案,并利用模糊验证技术和蜜罐口令方法增强口令安全。该文在随机谕言模型(Random Oracle Model, ROM)下证明了方案的安全性,并给出启发式安全分析。与相关身份认证方案的对比结果表明,该文提出的身份认证方案在提供安全性的同时能够适用于资源受限的无线传感器网络。

适用于工业物联网的基于证书的代理聚合签名方案

随着工业物联网的发展,数据拥有方需要对大量的数据进行处理,同时,对数据的收集和传送效率提出更高的要求。在工业物联网系统中,数据拥有方领导为了减少工作量,可以通过授权部门主管对数据进行相关处理。密码学中,代理聚合签名可以安全可靠的实现权利的委托授权,同时通过签名的聚合后,减少了数据的存储空间,提高数据的传输效率和验证效率。因此,设计一个高效的代理聚合签名方案是有必要的。首先,提出了一个适用于工业物联网的高效安全的基于证书的代理聚合签名方案。其次,在随机预言模型下,基于椭圆曲线上离散对数困难问题,给出了安全性证明。最后,通过与其他代理聚合签名方案计算效率和安全性的比较,结果表明新方案的计算效率更高。

移动医疗系统中的可撤销无证书代理重签名方案

代理重签名在保证委托双方私钥安全的前提下,通过半可信代理实现了双方签名的转换,在本文方案中,通过代理重签名实现了在通信过程中终端用户对于身份的隐私要求。移动医疗服务系统因为其有限的计算和存储能力,需要借助云服务器来对医疗数据进行计算和存储。然而,在将医疗数据外包给云服务器后,数据便脱离了用户的控制,这给用户隐私带来了极大地安全隐患。现有的无证书代理重签名方案大多都不具有撤销功能,存在着密钥泄露等安全性问题。为了解决这一问题,本文提出了一种可撤销的无证书代理重签名方案,在不相互信任的移动医疗服务系统中,实现了医疗数据传输过程以及云存储过程中的用户匿名性,同时,本文方案具有单向性和非交互性,更适合在大规模的移动医疗系统中使用。此外,当用户私钥泄露时,本文利用KUNode算法实现了对用户的高效撤销,并利用移动边缘计算技术将更新密钥和撤销列表的管理外包给移动边缘计算设备,降低了第三方的计算成本,使其具有较低的延迟。最后,在随机谕言机模型下证明了所构造的方案在自适应选择消息攻击下的不可伪造性,并利用JPBC库与其他方案进行计算与通信开销的对比。其结果表明,本方案在具备更优越的功能的同时,具有较小的计算成本、通信成本和撤销成本。

基于SM2的可截取签名方案

数字签名是公钥密码体制的重要应用部分,可截取数字签名解决了签名的持有者在不与原始签名人交互的情况下,根据自身要求就可以对已签名的数据进行合理的截取操作.将SM2数字签名算法与可截取签名算法相结合,提出一种新的基于椭圆曲线离散对数的可截取签名方案.并在随机预言机模型下对该方案的安全性进行分析,该方案满足不可伪造性、隐私性以及可审计性,即使是不诚实的截取者也无法对签名结果进行抵赖.性能分析表明,该方案通过标量乘法使算法效率得到提升.

A Proxy Signature Scheme as Secure as Decisional Diffie-Hellman Problem

Based on decisional Difiie-Hcllman problem, we propose a simpleproxy-protected signature scheme In the random oracle model, we also carry out the strict securityproof for the proposed scheme. The security of the proposed scheme is not loosely related to thediscrete logarithm assumption hut tightly related to the decisional Diffie-Hellman assumption in therandom oracle model.

Identity-Based Proxy Verifiably Encrypted Signature Scheme

A Verifiably Encrypted Signature (VES) plays an essential role in the construction of a fair data exchange. The paper proposes an Identity-based Proxy Verifiably Encrypted Signature (IPVES) to combine the advantages of a proxy signature and a VES in order to delegate the signing capability of the VES of an entity called the original signer to another entity, called the proxy signer. In this IPVES scheme, the original signer delegates his/her signing capability to the proxy signer. The proxy signer issues a signature by using a proxy signing key, encrypts the signature under a designated public key, and subsequently convinces a verifier that the resulting ciphertext contains such a signature. We prove that the proposed IPVES scheme is secure in a random oracle model under the computational Diffie-Hellman assumption.

A Practical Approach to Attaining Chosen Ciphertext Security

Strong security in public key cryptography is not enongh; the encryption has to be achieved in an efficient way. OAEP or SAEP is only suitable for special applications （e. g. key transport）, and securely transporting message of any length is a challenge. Motivated by the hybrid encryption, we present a practical approach to achieve the （adaptively） chosen eiphertext security. The time cost of encryption/decryption of proposed scheme is similar to OAEP and the bandwidth of message recovery is 92% for standard security parameter, while RSA-OAEP is 84%. The scheme is also provably secure against adaptively chosen ciphertext attacks in the random oracle model. We conclude that the approach is practical in more extensive application.

A RING SIGNATURE SCHEME OVER BRAID GROUPS

Quantum algorithms bring great challenges to classical public key cryptosystems, which makes cryptosystems based on non-commutative algebraic systems hop topic. The braid groups, which are non-commutative, have attracted much attention as a new platform for constructing quantum attack-resistant cryptosystems. A ring signature scheme is proposed based on the difficulty of the root extraction problem over braid groups, which can resist existential forgery against the adaptively cho-sen-message attack under the random oracle model.

Active Authentication Protocol for IoV Environment with Distributed Servers

The Internet of Vehicles(IoV)has evolved as an advancement over the conventional Vehicular Ad-hoc Networks(VANETs)in pursuing a more optimal intelligent transportation system that can provide various intelligent solutions and enable a variety of applications for vehicular traffic.Massive volumes of data are produced and communicated wirelessly among the different relayed entities in these vehicular networks,which might entice adversaries and endanger the system with a wide range of security attacks.To ensure the security of such a sensitive network,we proposed a distributed authentication mechanism for IoV based on blockchain technology as a distributed ledger with an ouroboros algorithm.Using timestamp and challenge-responsemechanisms,the proposed authentication model can withstand several security attacks such asMan-in-Middle(MiM)attacks,Distributed Denial of Service(DDoS)attacks,server spoofing attacks and more.The proposed method also provides a solution for single-point failure,forward secrecy,revocability,etc.We exhibit the security of our proposed model by using formal(mathematical)analysis and informal analysis.We used Random Oracle Model to perform themathematical analysis.In addition,we compared the communication cost,computation cost,and security of the proposed model with the related existing studies.We have verified the security of the model by using AVISPA tool simulation.The security analysis and computation analysis show that the proposed protocol is viable.

Unidirectional Identity-Based Proxy Re-Signature with Key Insulation in EHR Sharing System

The introduction of the electronic medical record(EHR)sharing system has made a great contribution to the management and sharing of healthcare data.Considering referral treatment for patients,the original signature needs to be converted into a re-signature that can be verified by the new organization.Proxy re-signature(PRS)can be applied to this scenario so that authenticity and nonrepudiation can still be insured for data.Unfortunately,the existing PRS schemes cannot realize forward and backward security.Therefore,this paper proposes the first PRS scheme that can provide key-insulated property,which can guarantee both the forward and backward security of the key.Although the leakage of the private key occurs at a certain moment,the forward and backward key will not be attacked.Thus,the purpose of key insulation is implemented.What’s more,it can update different corresponding private keys in infinite time periods without changing the identity information of the user as the public key.Besides,the unforgeability of our scheme is proved based on the extended Computational Diffie-Hellman assumption in the random oracle model.Finally,the experimental simulation demonstrates that our scheme is feasible and in possession of promising properties.

Provably Secure Self-Certified Signature Schemes with Message Recovery

To solve the key escrow problem of the identity-based cryptosystem, Girault introduced the notion of a self-certified public key, which not only eliminates the need to authenticate a public key but also solves the key escrow problem. This paper proposes a Self-Certified Signature (SCS) scheme with message recovery and two variants without using bilinear pairings: one is the authenticated encryption scheme in which only the designated receiver can verify the signature, and the other is the authenticated encryption scheme with message linkage that deals with large messages. These three SCS schemes are provably secure in the random oracle model and are more efficient than previous schemes.

Proofs of Security for Improved Rabin Signature Scheme

The improved RSA signature scheme can be strictly proved to be equivalent to the factoring problem. In the improved RSA signature scheme, when the public exponent e=1, the scheme becomes the improved Rabin signature. Such an improved Rabin signature scheme is reviewed and the techniques from the provable security is applied to analyze its security.

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 messages.To counter misuse,the anonymity 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 DiffieHellman 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.