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。     

基于身份的条件型广播代理重加密方案

在传统的代理重加密(PRE)体制中,代理者一旦获得重加密密钥就能将所有授权者能解密的密文转换成受理者能解密的密文,代理者的重加密权限过大;而且授权者需要对不同的受理者生成代理重加密密钥,计算过程中浪费了大量的资源。为了解决以上问题,构造了一种基于身份的条件型广播代理重加密方案。该方案中的授权者在生成重加密密钥过程中加入特殊条件,来限制代理者的重加密权限过大的问题;与此同时,使授权者的密文能够被再次广播以确保重要通信,这样的处理能节省更多的计算和通信开销。最后通过理论分析阐明了方案的安全性。     

标准模型下密钥保密的条件代理重加密

代理重加密方案(PRE)使代理者能够把用委托者公钥加密的密文转换成受委托者的密文,而代理者并不能得到明文。由于这个优良的特性,使得代理重加密广泛应用于加密后的信息通信领域,比如被加密的电子邮件传输等。但是,现有的条件代理重加密方案都不能提供密钥保密的特性。为此,本文基于3-QDBDH和Truncated q-ABDHE问题,提出第一个标准模型下达到CCA安全的密钥保密的条件重加密方案。     

条件型非对称跨加密系统的代理重加密方案

为了减轻云应用中移动设备解密的负担,利用基于身份的广播加密（IBBE）、基于身份的加密（IBE）、基于身份的条件型广播代理重加密方案,提出了多条件型非对称跨加密系统的代理重加密方案。该方案允许发送方将信息加密成IBBE密文,一次性发送给多个接收方,其中任一接收方又可以授权给代理者一个多条件型的重加密密钥,代理者利用该多条件型重加密密钥,能将符合多个条件的原始密文重加密成一个新的接收方可以解密的IBE密文。该方案实现了从IBBE加密系统到IBE加密系统的非对称代理重加密,而且代理者可以根据条件将最初的原始密文进行重加密,避免了不需要进行重加密的原始密文被代理者重加密,提高了代理者重加密的效率,同时节约了接收方获悉正确明文的时间。     

基于MQTT的数据加密传输算法

提出了一种改进MQTT协议的数据传输加密算法MQTT-EA （MQTT Encryption Algorithms）.该算法中,物联网设备端与服务器端随机生成自己的私钥,然后相互通知对方自己的私钥并通过算法组合成最终的会话主密钥,通过DES加密、解密,传输安全数据.模拟了敌手A、B对数据传输过程进行攻击,验证了在会话密钥生成算法没有泄露的前提下MQTT-EA是安全的.     

一种基于3G网络端到端加密的新型密钥管理方案研究

现今人与人之间传输数据时越来越依赖于3G移动通信网络,特别是第三代移动通信网络（3G）。尽管3G网络实现了网络组件内数据的机密性、完整性,但它并不提供用户端到端的机密性和完整性,而端到端加密的关键是有效地管理每一个密钥。因此文章提出了一种新的端到端加密的密钥管理方案,该方案基于三方Diffie、Hellman密钥协议算法,充分利用了3G的特殊性,只增加一种新的软件,几乎没有改变3G的物理结构。文章还对方案进行了评估,证明了该协议能够提供消息的机密性,以及通信双方双向认证的正确性。     

实现欧洲/电气安装总线协议数据加密和设备认证的方法

为了实现家居和建筑自动化(HBA)的数据安全传输,在欧洲安装总线(KNX/EIB)标准协议引入加密和认证机制;使用迪菲赫尔曼（Diffie-Hellman）算法实现非对称密钥共享,高级加密标准（AES）实现数据加密,基于哈希算法的挑战握手认证协议实现设备认证,使用控制器协调密钥分享和设备认证过程。模拟实验表明,所提方法在空间和时间上都是可行的,比其他改进方法更容易实现,操作更简单,能够保证数据的安全。     

格上基于RLWE难题的身份基代理重加密方案

针对目前基于格的身份基代理重加密方案存在的加/解密效率低和密文、密钥尺寸过长的问题,采用原像抽样和对偶加密技术,重新构造了一个基于格的身份基代理重加密方案。该方案采用原像抽样技术提取用户私钥,用对偶加密算法对消息进行加密,利用代理重加密密钥进行重加密,并用用户的私钥进行解密。安全分析表明,在标准模型下,基于ring learning with errors困难假设,该方案满足IND-aID-CPA安全。效率分析表明,该方案可以有效缩短密文和密钥尺寸,提高加/解密效率。     

云计算多授权中心CP-ABE代理重加密方案

代理重加密技术可使代理在不知道明文的条件下实现密文访问策略转换,这使代理重加密成为用户之间进行数据分享的重要技术。然而,代理重加密方案大多数是在单授权中心下构建的,存在授权机构权限大、易出现性能瓶颈和用户的计算开销大等问题。同时,大多数方案不满足代理重加密应具备的5个基本特性：单向性、可控性、非交互性、可重复性与可验证性。为解决以上问题,提出支持重复可控特性的云计算多授权中心CP-ABE（ciphertext-policy attribute-based encryption）代理重加密方案。在密文策略属性加密方案的基础上,引入代理加密和代理解密服务器从而减小用户客户端的计算开销,设置多个属性授权中心来分散中央机构权限。对代理重加密技术进行改进：在重加密密钥中设置随机因子和密文子项来实现单向性和可控性;设置的重加密密钥由客户端独立生成,不需要其他服务器参与,可实现非交互性,即可在数据拥有者为不在线状态时也可以进行数据分享;在初始密文中设置密文子项,对其多次加密即可实现重复性;在初始密文中设置验证子项,用户可验证外包以及重加密结果正确与否。通过与其他方案对比发现,所提方案的用户客户端计算开销较小,用户只需进行常数次的指数运算即可对原始密文解密,且安全性分析表明,所提方案基于q-parallel BDHE假设,在标准模型下可抵抗选择密文攻击。     

格上基于身份的可问责代理重加密方案

针对目前基于格的代理重加密方案中存在密钥滥用和数字证书管理等问题,引入问责机制,提出一种新的基于身份的可问责代理重加密方案。该方案采用用户身份ID计算生成矩阵作为公钥,并使用原像采样算法提取私钥,解决了数字证书管理的问题;使用双方用户公钥计算生成重密钥,提高了加/解密时的计算效率;使用代理商公私钥参与重加密运算,完成问责算法,有效地抑制了代理商和被授权者共谋的行为。安全性分析表明方案满足选择明文攻击安全;在效率方面,方案的计算复杂度和密文开销较小。     

A pairing-free certificate-based proxy re-encryption scheme for secure data sharing in public clouds

To assure the confidentiality of the sensitive data stored in public cloud storages, the data owners should encrypt their data before submitting them to the clouds. However, it brings new challenge for us to effectively share the encrypted data in the public clouds. The paradigm of proxy re-encryption provides a promising solution to data sharing as it enables a data owner to delegate the decryption rights of the encrypted data to the authorized recipients without any direct interaction. Certificate-based proxy re-encryption is a new cryptographic primitive to effectively support the data confidentiality in public cloud storages, which enjoys the advantages of certificate-based encryption while providing the functionalities of proxy re-encryption. In this paper, we propose a certificate-based proxy re-encryption scheme without bilinear pairings. The proposed scheme is proven secure under the computational Diffie-Hellman assumption in the random oracle model. Due to avoiding the time-consuming bilinear pairing operations, the proposed scheme significantly reduces the computation cost. Compared to the previous certificate-based proxy re-encryption schemes with bilinear pairings, it enjoys obvious advantage in the computation efficiency, and thus is more suitable for the computation-limited or power-constrained devices.     

基于MQTT协议扩展的IoT设备完整性监控

随着物联网飞速发展, 设备数量呈指数级增长, 随之而来的IoT安全问题也受到了越来越多的关注. 通常IoT设备完整性认证采用软件证明方法实现设备完整性校验, 以便及时检测出设备中恶意软件执行所导致的系统完整性篡改. 但现有IoT软件证明存在海量设备同步证明性能低、通用IoT通信协议难以扩展等问题. 针对这些问题, 本文提供一种轻量级的异步完整性监控方案, 在通用MQTT协议上扩展软件证明安全认证消息, 异步推送设备完整性信息, 在保障IoT系统高安全性的同时, 提高了设备完整性证明验证效率. 我们的方案实现了以下3方面安全功能: 以内核模块方式实现设备完整性度量功能, 基于MQTT的设备身份和完整性轻量级认证扩展, 基于MQTT扩展协议的异步完整性监控. 本方案能够抵抗常见的软件证明和MQTT协议攻击, 具有轻量级异步软件证明、通用MQTT安全扩展等特点. 最后在基于MQTT的IoT认证原型系统的实验结果表明, IoT节点的完整性度量、MQTT协议连接认证、PUBLISH报文消息认证性能较高, 都能满足海量IoT设备完整性监控的应用需求.     

Incremental proxy re-encryption scheme for mobile cloud computing environment

Due to the limited computational capability of mobile devices, the research organization and academia are working on computationally secure schemes that have capability for offloading the computational intensive data access operations on the cloud/trusted entity for execution. Most of the existing security schemes, such as proxy re-encryption, manager-based re-encryption, and cloud-based re-encryption, are based on El-Gamal cryptosystem for offloading the computational intensive data access operation on the cloud/trusted entity. However, the resource hungry pairing-based cryptographic operations, such as encryption and decryption, are executed using the limited computational power of mobile device. Similarly, if the data owner wants to modify the encrypted file uploaded on the cloud storage, after modification the data owner must encrypt and upload the entire file on the cloud storage without considering the altered portion(s) of the file. In this paper, we have proposed an incremental version of proxy re-encryption scheme for improving the file modification operation and compared with the original version of the proxy re-encryption scheme on the basis of turnaround time, energy consumption, CPU utilization, and memory consumption while executing the security operations on mobile device. The incremental version of proxy re-encryption scheme shows significant improvement in results while performing file modification operations using limited processing capability of mobile devices.     

Sharing your privileges securely: a key-insulated attribute based proxy re-encryption scheme for IoT

Attribute based proxy re-encryption (ABPRE) combines the merits of proxy re-encryption and attribute based encryption, which allows a delegator to re-encrypt the ciphertext according to the delegatees’ attributes. The theoretical foundations of ABPRE has been well studied, yet to date there are still issues in schemes of ABPRE, among which time-bounded security and key exposure protection for the re-encryption keys are the most concerning ones. Within the current ABPRE framework, the re-encryption keys are generated independently of the system time segments and the forward security protection is not guaranteed when the users’ access privileges are altered. In this paper, we present a key-insulated ABPRE scheme for IoT scenario. We realize secure and fine-grained data sharing by utilizing attribute based encryption over the encrypted data, as well as adopting key-insulation mechanism to provide forward security for re-encryption keys and private keys of users. In particular, the lifetime of the system is divided into several time slices, and when system enters into a new slice, the user’s private keys need are required to be refreshed. Therefore, the users’ access privileges in our system are time-bounded, and both re-encryption keys and private keys can be protected, which will enhance the security level during data re-encryption, especially in situations when key exposure or privilege alternation happens. Our scheme is proved to be secure under MDBDH hardness assumptions as well as against collusion attack. In addition, the public parameters do not have to be changed during the evolution of users’ private keys, which will require less computation resources brought by parameter synchronization in IoT.     

基于多路密钥协商的物联网安全通信方法

物联网具有终端异构、信息传输复杂、应用安全要求多样化等特点,并且物联网的终端大多处理能力有限,因此物联网中通信的安全问题较互联网更为严峻,而传统的单路传输安全方法无法在保证安全的同时降低运算的复杂度,不太适用于物联网环境。针对上述问题,提出将传统的加密技术与多路传输相结合,设计一种端到端的安全多路通信方法。该方法的基本思想是通信双方选择多条不同的传输路径,采用Diffie Hellman算法进行密钥协商,将密钥协商信息分片并根据选择的路径发送给接收方,这样便协商出一个安全的会话密钥。然后,发送方使用该密钥加密数据并将得到的密文分片经多路传输。分析表明,相比于单路传输的安全通信方法能更好地对抗中间人攻击、密钥破解等安全问题,并在一定程度上降低运算复杂度。     

高效的基于证书代理重加密方案

已有基于证书代理重加密方案的构造严重依赖双线性对运算,计算效率不高。针对这一问题,提出了一个高效的基于证书代理重加密方案。所提出方案的加密算法无须作双线性对运算,而其他算法至多作一次双线性对运算,因此显著提高了方案的计算性能。与现有基于证书代理重加密方案相比,该方案具有计算效率高和通信带宽低的优点。基于[q-mBDHI]问题和[1-BDHI]问题的困难性假设,该方案在随机预言模型下被严格证明满足适应性选择密文攻击下的密文不可区分安全性,即满足选择密文安全性。     

A lightweight remote user authentication scheme for IoT communication using elliptic curve cryptography

Internet of things (IoT) has become a new era of communication technology for performing information exchange. With the immense increment of usage of smart devices, IoT services become more accessible. To perform secure transmission of data between IoT network and remote user, mutual authentication, and session key negotiation play a key role. In this research, we have proposed an ECC-based three-factor remote user authentication scheme that runs in the smart device and preserves privacy, and data confidentiality of the communicating user. To support our claim, multiple cryptographic attacks are analyzed and found that the proposed scheme is not vulnerable to those attacks. Finally, the computation and communication overheads of the proposed scheme are compared with other existing protocols to confirm that the proposed scheme is lightweight. A formal security analysis using AVISPA simulation tool has been done that confirms the proposed scheme is robust against relevant security threats.