Some Remarks on Cocks'Identity-Based Encryption Scheme

The theory of quadratic residues plays an important role in cryptography.In 2001,Cocks developed an identity-based encryption(IBE)scheme based on quadratic residues,resolving Shamir’s 17-year-old open problem.However,a notable drawback of Cocks’scheme is the significant expansion of the ciphertext,and some of its limitations have been addressed in subsequent research.Recently,Cotan and Teşeleanu highlighted that previous studies on Cocks’scheme relied on a trial-and-error method based on Jacobi symbols to generate the necessary parameters for the encryption process.They enhanced the encryption speed of Cocks’scheme by eliminating this trialand-error method.Based on security analysis,this study concludes that the security of Cotan-Teşeleanu’s proposal cannot be directly derived from the security of the original Cocks’scheme.Furthermore,by adopting the Cotan-Teşeleanu method and introducing an additional variable as a public element,this study develops a similar enhancement scheme that not only accelerates the encryption speed but also provides security equivalent to the original Cocks’scheme.

Construction and Implementation of a Privacy-Preserving Identity-Based Encryption Architecture

A recent proposal by Adams integrates the digital credentials (DC) technology of Brands with the identity-based encryption (IBE) technology of Boneh and Franklin to create an IBE scheme that demonstrably enhances privacy for users. We refer to this scheme as a privacy-preserving identity-based encryption (PP-IBE) construction. In this paper, we discuss the concrete implementation considerations for PP-IBE and provide a detailed instantiation (based on q-torsion groups in supersingular elliptic curves) that may be useful both for proof-of-concept purposes and for pedagogical purposes.

Fully Secure Identity-based Broadcast Encryption in the Subgroups

In this paper,we show how to use the dual techniques in the subgroups to give a secure identity-based broadcast encryption(IBBE) scheme with constant-size ciphertexts. Our scheme achieves the full security(adaptive security) under three static(i.e. non q-based) assumptions. It is worth noting that only recently Waters gives a short ciphertext broadcast encryption system that is even adaptively secure under the simple assumptions. One feature of our methodology is that it is relatively simple to leverage our techniques to get adaptive security.

OBLIVIOUS TRANSFER WITH ACCESS CONTROL AND IDENTITY-BASED ENCRYPTION WITH ANONYMOUS KEY ISSUING

In ACM'CCS 2009,Camenisch,et al.proposed the Oblivious Transfer with Access Control(AC-OT) in which each item is associated with an attribute set and can only be available,on request,to the users who have all the attributes in the associated set.Namely,AC-OT achieves access control policy for conjunction of attributes.Essentially,the functionality of AC-OT is equivalent to the sim-plified version that we call AC-OT-SV:for each item,one attribute is associated with it,and it is requested that only the users who possess the associated attribute can obtain the item by queries.On one hand,AC-OT-SV is a special case of AC-OT when there is just one associated attribute with each item.On the other hand,any AC-OT can be realized by an AC-OT-SV.In this paper,we first present a concrete AC-OT-SV protocol which is proved to be secure in the model defined by Camenisch,et al..Then from the protocol,interestingly,a concrete Identity-Based Encryption(IBE) with Anonymous Key Issuing(AKI) is given which is just a direct application to AC-OT-SV.By comparison,we show that the AKI protocol we present is more efficient in communications than that proposed by Chow.

An Efficient Identity-Based Homomorphic Broadcast Encryption

Broadcast encryption (BE) allows a sender to broadcast its message to a set of receivers in a single ciphertext. However, in broadcast encryption scheme, ciphertext length is always related to the size of the receiver set. Thus, how to improve the communication of broadcast encryption is a big issue. In this paper, we proposed an identity-based homomorphic broadcast encryption scheme which supports an external entity to directly calculate ciphertexts and get a new ciphertext which is the corresponding result of the operation on plaintexts without decrypting them. The correctness and security proofs of our scheme were formally proved. Finally, we implemented our scheme in a simulation environment and the experiment results showed that our scheme is efficient for practical applications.

Security Analysis of a Privacy-Preserving Identity-Based Encryption Architecture

Identity-Based Encryption (IBE) has seen limited adoption, largely due to the absolute trust that must be placed in the private key generator (PKG)—an authority that computes the private keys for all the users in the environment. Several constructions have been proposed to reduce the trust required in the PKG (and thus preserve the privacy of users), but these have generally relied on unrealistic assumptions regarding non-collusion between various entities in the system. Unfortunately, these constructions have not significantly improved IBE adoption rates in real-world environments. In this paper, we present a construction that reduces trust in the PKG without unrealistic non-collusion assumptions. We achieve this by incorporating a novel combination of digital credential technology and bilinear maps, and making use of multiple randomly-chosen entities to complete certain tasks. The main result and primary contribution of this paper are a thorough security analysis of this proposed construction, examining the various entity types, attacker models, and collusion opportunities in this environment. We show that this construction can prevent, or at least mitigate, all considered attacks. We conclude that our construction appears to be effective in preserving user privacy and we hope that this construction and its security analysis will encourage greater use of IBE in real-world environments.

Identity-Based Steganography in Spatial Domain

This paper proposed an identity-based steganographic scheme, where a receiver with certain authority can recover the secret message ready for him, but cannot detect the existence of other secret messages. The proposed scheme created several separate covert communication channels tagged by the Fuzzy Identity-Based Encryption (FIBE) in one grayscale image. Then each channel is used to embed one secret message by using any content-aware steganographic scheme. Receivers with different attributes can extract different messages corresponded. The Experiments illustrated the feasibility of this identity-based secret message extraction. Further, the proposed scheme presents high undetectability against steganalytic attack launched by receivers without corresponded attributes.

基于在线/离线技术的SM9-IBE加密方案研究

基于SM9-IBE密码算法,提出了一种适用于轻量级设备的高效在线/离线加密方案,以解决轻量级设备加密重要数据的时效性问题。通过将复杂计算进行预处理实现加密轻量化,对方案进行安全性证明和时间性能分析,与传统的SM9-IBE算法相比,改进的SM9-IBE算法在保证安全性的同时提高了加密速度和轻量级设备的资源利用率,具有较好的安全性和时间性能。

SA-IBE:一种安全可追责的基于身份加密方案

基于身份加密(Identity-Based Encryption,IBE)方案中,用户公钥直接由用户身份得到,可以避免公钥基础设施(Public Key Infrastructure,PKI)系统的证书管理负担。但IBE存在密钥托管问题,即私钥生成器(PrivateKey Generator,PKG)能够解密用户密文或泄漏用户私钥,而现有解决方案一般需要安全信道传输私钥,且存在用户身份认证开销大或不能彻底解决密钥托管问题的缺陷。该文提出一种安全可追责的基于身份加密方案,即SA-IBE方案,用户原私钥由PKG颁发,然后由多个密钥隐私机构并行地加固私钥隐私,使得各机构无法获取用户私钥,也不能单独解密用户密文;设计了高效可追责的单点PKG认证方案;并采用遮蔽技术取消了传输私钥的安全信道。文中基于标准的Diffie-Hellman假设证明了SA-IBE方案的安全性、解决密钥托管问题的有效性以及身份认证的可追责性。

基于IBE和数字水印的电子印章解决方案

为了满足电子交易中电子文档的可用性、安全性、权威性,提出了一种基于IBE(Identity Based Encryp-tion)技术和数字水印技术的电子印章解决方案。该方案使用IBE技术分配成对的密钥完成水印的嵌入和提取验证。在保证与基于PKI(Public Key Infrastructure)技术的印章系统具有等同安全强度的同时,具有降低成本、提高效率的优点。

基于身份别名的加入辅助认证方的IBE方案

用户如何向PKG证明自己的身份以及PKG如何安全地将用户的私钥送到用户的手中是IBE系统面临的两大技术问题。本文通过加入辅助认证方(TA)的方式实现信任转移,解决密钥托管的问题。用户的私钥由用户和PKG共同产生,通过引入身份别名,方便了私钥更新。分析表明,该方案在保证安全性的同时,解决了部署IBE系统所遇到的问题,明显扩大了IBE系统的可应用范围。

一种基于种子密钥SPK的IBE加密体制设计方案

该文根据IBE加密体制的思想,应用基于椭圆曲线SPK的密钥管理体制,设计了一种基于椭圆曲线SPK的IBE加密体制。该体制免除了复杂的CA证书认证过程,满足加密卡节省存储空间和生成密钥对方便的要求,为加密卡的优化提供了一种新思路。

基于信任服务的IBE系统

针对现有的基于身份的加密(Identity Based Encryption,IBE)系统缺少标识管理、权限管理、密钥管理,没有解决域间互操作的问题。通过在现有的IBE系统上增加4个管理机制完善系统。设计了基于信任服务的IBE系统。介绍了该方案的系统架构和工作原理,并将该方案与PKI系统进行对比,对比结果证明了其高安全性、高效率、低成本的优势。

HIBE-MPJ:一种基于HIBE的物联网环境下跨域通信机制研究

基于身份的加密方案解决了传统公钥加密体制在证书管理方面的不足,使基于身份的加密方案能适应物联网轻量级的环境。针对基于身份加密在物联网环境中的应用存在密钥托管和跨域认证等问题,提出一种分层的基于身份加密(Hierarchical Identity-Based Encryption,HIBE)的物联网环境下多私钥生成机构(Private Key Generator,PKG)联合跨域认证及通信机制HIBE-MPJ(Hierarchical Identity-Based Encryption-Multiple Private Key Generator Joint)。HIBE-MPJ使用不同信任域的PKG作为跨域认证时的信任网关,通过密钥共享解决不同信任域PKG的密钥托管问题,并建立安全的通信密钥协商机制,使得不同系统参数的两个物联网信任域内的用户节点能互相认证,并提高通信时的效率。随后对认证过程给出了正确性分析,并分析了该方案在随机预言模型下的安全性,并加以实验测试分析,实验结果表明,HIBE-MPJ具有安全性及可行性。最后通过理论证明和构建物联网环境进行实验测试,实验结果表明HIBE-MPJ模型的安全性和可行性。

基于IBE的XML加密数据安全交换研究

当前XML加密普遍采用对称算法和非对称算法组合的"二次"加密方式,并且密钥交换依赖传统PKI体制,存在加/解密过程复杂等缺陷。通过对XML加密规范和IBE体制以及双线性映射算法的研究,提出采用IBE密钥机制和双线性映射算法实现XML加密的数据安全交换方案,对相应的XML数据交换过程和XML加密文件结构进行了设计,对该方式的XML加密关键环节实现方式做了具体阐述。作为一种新型XML加密方案,在保证数据安全交换的同时,简化了XML加密过程,并克服了传统PKI的缺陷。

基于IBE技术的学分制管理系统安全解决方案

针对目前学分制管理系统存在的数据存储不加密、数据传输不安全、身份验证不严格等问题,分析了用PKI技术解决这些问题的不足,提出了一种基于身份加密技术的改进方案。采用表示用户身份的任意字符串作为公钥、严格验证用户身份、对关键数据进行数字签名、网络传输使用安全连接等方法,保证了数据存储、传输等过程的机密性、完整性、可用性和不可抵赖性,克服了传统PKI技术产生、存储和管理公钥麻烦、系统实现复杂、成本高、效率低等缺点。理论分析和实验结果表明该方法是学分制管理系统安全问题的较好解决方案。

基于组合公钥的IBE算法

为提高基于身份加密(IBE)算法的安全性,设计一种基于组合公钥(CPK)的IBE算法。按照CPK中用户密钥生成方法生成用户公钥,实现身份到椭圆曲线点群的映射,利用系统主密钥矩阵代替单个系统主密钥,扩展系统主密钥空间,从而降低单个系统主密钥泄露导致系统被攻破的风险。理论分析表明,该算法具有大规模密钥管理与公钥认证简单的优势,且不存在共谋攻击。

基于IBE加密算法的远程抄表系统的优化

针对天津机场的能源计量系统在数据采集时,实际存在的部分表具仍然需要抄表人员去现场抄表的问题,设计了一种基于IBE加密算法进行通信加密的433 MHz射频通信模块子系统,实现了对主系统的优化。系统硬件采用C8051F310单片机和CC1101无线发射接收部分作为无线传输模块,由数据传输单元通过GPRS网络与上位机系统通信,实现对表具数据的远程安全采集。最后展示了该子系统并入主系统后的实际运行效果。通过对该系统的优化,实现了通信安全的远程抄表功能。

LogIDStamp:一个基于IBE的日志身份戳系统

针对计算机系统和用户行为日志安全问题,提出日志身份戳、日志安全身份戳、前向安全的日志身份戳等概念,并利用基于身份的公钥加密体制(IBE)设计日志安全身份戳系统,实现对日志审计用户的身份追溯和满足前向安全的日志加密等功能.IBE加密体制无需PKI公钥证书,可灵活实现基于身份标识的加密和签名.首先在研究IBE加密体制的基础上,实现以密钥管理为中心的IBE应用系统;将IBE应用于日志身份戳的设计,提出了一个基于IBE的安全日志身份戳应用系统LogIDStamp,并分析了系统应用的安全问题;最后实现系统测试,与PKI日志加密作性能比较,体现了安全和性能优势.

一种IBE机制下的端到端密钥管理方案

密钥管理是基于移动通信系统进行端到端加密的核心问题,现有方案大多依赖于密钥管理中心,并存在不在同一加密组内的终端要进行端到端加密通信时通信消耗大、效率低等问题。为解决这些问题,提出一种基于IBE(Identity Based Encryption)的三级密钥管理方案。该方案适于在资源有限的移动终端上使用,采用IBE机制生成和管理主密钥,简化了密钥协商过程,降低了对密钥管理中心的依赖,使用对称加密算法加密通信信息,确保通信的高效性。通信双方可进行双向认证,具有前向安全性,可抵抗选择密文攻击。