Zero knowledge based client side deduplication for encrypted files of secure cloud storage in smart cities

As typical applications in the field of the cloud computing, cloud storage services are popular in the development of smart cities for their low costs and huge storage capacity. Proofs-of-ownership (PoW) is an important cryptographic primitive in cloud storage to ensure that a client holds the whole file rather than part of it in secure client side data deduplication. The previous PoW schemes worked well when the file is in plaintext. However, the privacy of the clients’ data may be vulnerable to honest-but-curious attacks. To deal with this issue, the clients tend to encrypt files before outsourcing them to the cloud, which makes the existing PoW schemes inapplicable any more. In this paper, we first propose a secure zero-knowledge based client side deduplication scheme over encrypted files. We prove that the proposed scheme is sound, complete and zero-knowledge. The scheme can achieve a high detection probability of the clients’ misbehavior. Then we introduced a proxy re-encryption based key distribution scheme. This scheme ensures that the server knows nothing about the encryption key even though it acts as a proxy to help distributing the file encryption key. It also enables the clients who have gained the ownership of a file to share the file with the encryption key generated without establishing secure channels among them. It is proved that the clients’ private key cannot be recovered by the server or clients collusion attacks during the key distribution phase. Our performance evaluation shows that the proposed scheme is much more efficient than the existing client side deduplication schemes.     

A secure user anonymity-preserving biometric-based multi-server authenticated key agreement scheme using smart cards

Advancement in communication technology provides a scalable platform for various services, where a remote user can access the server from anywhere without moving from its place. It provides a unique opportunity for online services such that a user does not need to be physically present at the service center. These services adopt authentication and key agreement protocols in order to ensure authorized and secure access to the resources. Most of the authentication schemes proposed in the literature support a single-server environment, where the user has to register with each server. If a user wishes to access multiple application servers, he/she requires to register with each server. The multi-server authentication introduces a scalable platform such that a user can interact with any server using single registration. Recently, Chuang and Chen proposed an efficient multi-server authenticated key agreement scheme based on a user’s password and biometrics (Chuang and Chen, 2014). Their scheme is a lightweight, which requires the computation of only hash functions. In this paper, we first analyze Chuang and Chen’s scheme and then identify that their scheme does not resist stolen smart card attack which causes the user’s impersonation attack and server spoofing attack. We also show that their scheme fails to protect denial-of-service attack. We aim to propose an efficient improvement on Chuang and Chen’s scheme to overcome the weaknesses of their scheme, while also retaining the original merits of their scheme. Through the rigorous informal and formal security analysis, we show that our scheme is secure against various known attacks including the attacks found in Chuang and Chen’s scheme. Furthermore, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure against the replay and man-in-the-middle attacks. In addition, our scheme is comparable in terms of the communication and computational overheads with Chuang and Chen’s scheme and other related existing schemes.     

Intrusion-Tolerant Server Architecture for Survivable Services

Survivable systems are increasingly needed in a wide range of applications. As a step toward realizing survivable systems, this paper presents architecture of intrusion-tolerant servers. It is to deliver intended services transparently to the clients even when a computing node fails due to failures, intrusions, and other threats. In order to deliver only secure results to the client, we need an algorithm to decide agreement on results from replicated servers. For this purpose, a secure and practical decentralized voting algorithm for the architecture is proposed in the paper. Through the experiments on a test-bed, especially, for web services, the approach turned out very effective in terms of extra cost and considered to be able to cope with both confidentiality and integrity attacks.     

On improving resistance to Denial of Service and key provisioning scalability of the DTLS handshake

DTLS is a transport layer security protocol designed to provide secure communication over unreliable datagram protocols. Before starting to communicate, a DTLS client and server perform a specific handshake in order to establish a secure session and agree on a common security context. However, the DTLS handshake is affected by two relevant issues. First, the DTLS server is vulnerable to a specific Denial of Service (DoS) attack aimed at forcing the establishment of several half-open sessions. This may exhaust memory and network resources on the server, so making it less responsive or even unavailable to legitimate clients. Second, although it is one of the most efficient key provisioning approaches adopted in DTLS, the pre-shared key provisioning mode does not scale well with the number of clients, it may result in scalability issues on the server side, and it complicates key re-provisioning in dynamic scenarios. This paper presents a single and efficient security architecture which addresses both issues, by substantially limiting the impact of DoS, and reducing the number of keys stored on the server side to one unit only. Our approach does not break the existing standard and does not require any additional message exchange between DTLS client and server. Our experimental results show that our approach requires a shorter amount of time to complete a handshake execution and consistently reduces the time a DTLS server is exposed to a DoS instance. We also show that it considerably improves a DTLS server in terms of service availability and robustness against DoS attack.     

Application-Aware Client-Side Data Reduction and Encryption of Personal Data in Cloud Backup Services

Cloud backup has been an important issue ever since large quantities of valuable data have been stored on the personal computing devices. Data reduction techniques, such as deduplication, delta encoding, and Lempel-Ziv （LZ） compression, performed at the client side before data transfer can help ease cloud backup by saving network bandwidth and reducing cloud storage space. However, client-side data reduction in cloud backup services faces efficiency and privacy challenges. In this paper, we present Pangolin, a secure and efficient cloud backup service for personal data storage by exploiting application awareness. It can speedup backup operations by application-aware client-side data reduction technique, and mitigate data security risks by integrating selective encryption into data reduction for sensitive applications. Our experimental evaluation, based on a prototype implementation, shows that our scheme can improve data reduction efficiency over the state-of-the-art methods by shortening the backup window size to 33%-75%, and its security mechanism for＇ sensitive applications has negligible impact on backup window size.     

Intrusion-tolerant server architecture for survivable services

Survivable systems are increasingly needed in a wide range of applications. As a step toward realizing survivable systems, this paper presents architecture of intrusion-tolerant servers. It is to deliver intended services transparently to the clients even when a computing node fails due to failures, intrusions, and other threats. In order to deliver only secure results to the client, we need an algorithm to decide agreement on results from replicated servers. For this purpose, a secure and practical decentralized voting algorithm for the architecture is proposed in the paper. Through the experiments on a test-bed, especially, for web services, the approach turned out very effective in terms of extra cost and considered to be able to cope with both confidentiality and integrity attacks.     

Remote user authentication and key agreement for mobile client–server environments on elliptic curve cryptography

In recent years, with the rapid advance of wireless mobile networks, secure and efficient authentication mechanisms that can operate over insecure wireless channels have become increasingly essential. To improve the efficiency in the energy-limited mobile devices, many authentication schemes using elliptic curve cryptography (ECC) have been presented. However, these schemes are still inefficient in terms of computation cost and communication overhead. Moreover, they suffer from various attacks, making them impractical due to their inherent design. To address their weaknesses, we propose a more efficient ID-based authentication scheme on ECC for mobile client–server environments with considering security requirements. The proposed scheme not only provides mutual authentication but also achieves session key agreement between the client and the server. Through a rigorous formal security proof under random oracle model, it has been indicated that the proposed protocol is secure against security threats. The informal security analysis shows that our scheme can resist well-known attacks and provides user anonymity. Performance analysis and comparison results demonstrate that our scheme outperforms the related competitive works and is more suitable for practical application in mobile client–server environments.     

A countable and time-bound password-based user authentication scheme for the applications of electronic commerce

In this paper, we propose a secure and efficient user authentication scheme with countable and time-bound features. The countable feature is to limit the use to a certain number of times, which means that the users are able to successfully log into the system in a fixed number of times. The feature of the time-bound allows each login ticket to have a period of expiration. In other words, if a login request is overdue, it would not be available anymore. These features make our scheme more reliable for applications in the field of electronic commerce, such as on-line games, pay-TV, and so on. Since our scheme does not require any password or verification table and can avoid replay attacks, it is under firm security. Moreover, our scheme shows a lower computational overhead on the user side. Therefore, it offers an efficient and adequate alternative for the implementations in the mobile environment with limited computing capability.     

A Generic Framework for Anonymous Authentication in Mobile Networks

Designing an anonymous user authentication scheme in global mobility networks is a non-trivial task because wireless networks are susceptible to attacks and mobile devices powered by batteries have limited communication, processing and storage capabilities. In this paper, we present a generic construction that converts any existing secure password authen- tication scheme based on a smart card into an anonymous authentication scheme for roaming services. The security proof of our construction can be derived from the underlying password authentication scheme employing the same assumptions. Compared with the original password authentication scheme, the transformed scheme does not sacrifice the authentication effciency, and additionally, an agreed session key can be securely established between an anonymous mobile user and the foreign agent in charge of the network being visited. Furthermore, we present an instantiation of the proposed generic construction. The performance analysis shows that compared with other related anonymous authentication schemes, our instantiation is more effcient.     

SPP: An anti-phishing single password protocol

Most users have multiple accounts on the Internet where each account is protected by a password. To avoid the headache in remembering and managing a long list of different and unrelated passwords, most users simply use the same password for multiple accounts. Unfortunately, the predominant HTTP basic authentication protocol (even over SSL) makes this common practice remarkably dangerous: an attacker can effectively steal users’ passwords for high-security servers (such as an online banking website) by setting up a malicious server or breaking into a low-security server (such as a high-school alumni website). Furthermore, the HTTP basic authentication protocol is vulnerable to phishing attacks because a client needs to reveal his password to the server that the client wants to login.In this paper, we propose a protocol that allows a client to securely use a single password across multiple servers, and also prevents phishing attacks. Our protocol achieves client authentication without the client revealing his password to the server at any point. Therefore, a compromised server cannot steal a client’s password and replay it to another server.Our protocol is simple, secure, efficient and user-friendly. In terms of simplicity, it only involves three messages. In terms of security, the protocol is secure against the attacks that have been discovered so far including the ones that are difficult to defend, such as the malicious server attacks described above and the recent phishing attacks. Essentially our protocol is an anti-phishing password protocol. In terms of efficiency, each run of our protocol only involves a total of four computations of a one-way hash function. In terms of usability, the protocol requires a user to remember only one password consisting of eight (or more) random characters, and this password can be used for all of his accounts.     

Tight chosen ciphertext attack （CCA）-secure hybrid encryption scheme with full public verifiability

In this paper, we propose a new ＂full public verifiability＂ concept for hybrid public-key encryption schemes. We also present a new hybrid public-key encryption scheme that has this feature, which is based on the decisional bilinear Diffie-Hellman assumption. We have proven that the new hybrid public-key encryption scheme is secure against adaptive chosen ciphertext attack in the standard model. The ＂full public verifiability＂ feature means that the new scheme has a shorter ciphertext and reduces the security requirements of the symmetric encryption scheme. Therefore, our new scheme does not need any message authentication code, even when the one-time symmetric encryption scheme is passive attacks secure. Compared with all existing publickey encryption schemes that are secure to the adaptive chosen ciphertext attack, our new scheme has a shorter ciphertext, efficient tight security reduction, and fewer requirements （if the symmetric encryption scheme can resist passive attacks）.     

End-to-end security scheme for mobility enabled healthcare Internet of Things

We propose an end-to-end security scheme for mobility enabled healthcare Internet of Things (IoT). The proposed scheme consists of (i) a secure and efficient end-user authentication and authorization architecture based on the certificate based DTLS handshake, (ii) secure end-to-end communication based on session resumption, and (iii) robust mobility based on interconnected smart gateways. The smart gateways act as an intermediate processing layer (called fog layer) between IoT devices and sensors (device layer) and cloud services (cloud layer). In our scheme, the fog layer facilitates ubiquitous mobility without requiring any reconfiguration at the device layer. The scheme is demonstrated by simulation and a full hardware/software prototype. Based on our analysis, our scheme has the most extensive set of security features in comparison to related approaches found in literature. Energy-performance evaluation results show that compared to existing approaches, our scheme reduces the communication overhead by 26% and the communication latency between smart gateways and end users by 16%. In addition, our scheme is approximately 97% faster than certificate based and 10% faster than symmetric key based DTLS. Compared to our scheme, certificate based DTLS consumes about 2.2 times more RAM and 2.9 times more ROM resources. On the other hand, the RAM and ROM requirements of our scheme are almost as low as in symmetric key-based DTLS. Analysis of our implementation revealed that the handover latency caused by mobility is low and the handover process does not incur any processing or communication overhead on the sensors.     

An efficient improvement remote user mutual authentication and session key agreement scheme for E-health care systems

The E-health care systems allow patients to gain the health monitoring facility and access medical services remotely. A secure mechanism for mutual authentication and session key agreement is the most important requirements for E-Health Care Systems. Recently, Amin et al.’s proposed a mutual authentication and session key agreement protocol and claimed that their scheme is secure against all possible attacks. In this paper, we show that not only their scheme is vulnerable to privileged-insider attack, replay attack, session key disclosure attack, but also does not provide patient untraceability and backward secrecy. In order to withstand the mentioned security weaknesses, we propose an efficient remote mutual authentication scheme for the systems which are using ECC and Fuzzy Extractor. The proposed scheme not only resists against different security attacks, but it also provides an efficient registration, login, mutual authentication, session key agreement, and password and biometric update phases. During the experimentation, it has been observed that the proposed scheme is secure against various known attacks. Beside, our scheme is robust against privileged-insider attack that it rarely checked in security analysis. The informal analysis will ensure that our scheme provides well security protection against the different security attacks. Furthermore, we analyzed the security of the scheme using AVISPA software and Random Oracle Model. The formal analysis results and performance evaluation vouch that our scheme is also secure and efficient in computation and communication cost.     

AAnA: Anonymous authentication and authorization based on short traceable signatures

Due to the privacy concerns prevailing in today’s computing environments, users are more likely to require anonymity or at least pseudonyms; on the other hand, they must be traceable or revokable in case of abuse. Meanwhile, an authorization mechanism that controls access rights of users to services or resources is frequently needed in various real-world applications but does not favor anonymity. To cope with these problems, we explore an anonymous authentication and authorization method that very efficiently supports fine-grained authorization services without losing strong but traceable anonymity. The efficiency of our method comes from atomizing authorization within a group and issuing multiple authorization values for a group membership. The cryptographic basis of our method is the famous short traceable signature scheme. Our method allows a user to selectively disclose authorization according to need and also provides revocation and update of authorization without revoking membership or anonymity. To prevent users from forging authorization, our method enables the users to prove their authorizations while hiding the corresponding authorization values from other users. We formally analyze security and compare the related methods in terms of efficiency and functionality. We show that our method is secure against misidentification, anonymity-break and framing attacks and is efficient within a reasonable bound while still providing various functionalities such as fine-grained authorization and authorization revocation, commonly required in many practical applications.     

Provably secure authenticated key agreement scheme for distributed mobile cloud computing services

With the rapid development of mobile cloud computing, the security becomes a crucial part of communication systems in a distributed mobile cloud computing environment. Recently, in 2015, Tsai and Lo proposed a privacy-aware authentication scheme for distributed mobile cloud computing services. In this paper, we first analyze the Tsai–Lo’s scheme and show that their scheme is vulnerable to server impersonation attack, and thus, their scheme fails to achieve the secure mutual authentication. In addition, we also show that Tsai–Lo’s scheme does not provide the session-key security (SK-security) and strong user credentials’ privacy when ephemeral secret is unexpectedly revealed to the adversary. In order to withstand these security pitfalls found in Tsai–Lo’s scheme, we propose a provably secure authentication scheme for distributed mobile cloud computing services. Through the rigorous security analysis, we show that our scheme achieves SK-security and strong credentials’ privacy and prevents all well-known attacks including the impersonation attack and ephemeral secrets leakage attack. Furthermore, we simulate our scheme for the formal security analysis using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool, and show that our scheme is secure against passive and active attacks including the replay and man-in-the-middle attacks. More security functionalities along with reduced computational costs for the mobile users make our scheme more appropriate for the practical applications as compared to Tsai–Lo’s scheme and other related schemes. Finally, to demonstrate the practicality of the scheme, we evaluate the proposed scheme using the broadly-accepted NS-2 network simulator.     

Signcryption with fast online signing and short signcryptext for secure and private mobile communication

Signcryption scheme is one of the useful tools for secure communication where authenticity and confidentiality are simultaneously required.Now,mobile devices are more and more widely used for communication,and thus it is desirable to design a scheme suitable to mobile applications.In this paper,we propose a signcryption scheme which is efficient enough to be implemented on mobile devices.In our scheme,we need only one multiplication in an online phase,and thus a signcryptor can generate a signcryptext very efficiently in the online phase.Moreover,the size of signcryptext is very short compared with exsiting schemes,and thus our scheme is very efficient in terms of communication overhead.The security of our signcryption scheme is proven in the random oracle model.     

A secure dynamic ID based remote user authentication scheme for multi-server environment

Since the number of server providing the facilities for the user is usually more than one, the authentication protocols for multi-server environment are required for practical applications. Most of password authentication schemes for multi-server environment are based on static ID, so the adversary can use this information to trace and identify the user's requests. It is unfavorable to be applied to special applications, such as e-commerce. In this paper, we develop a secure dynamic ID based remote user authentication scheme to achieve user's anonymity. The proposed scheme only uses hashing functions to implement a robust authentication scheme for the multi-server environment. It provides a secure method to update password without the help of third trusted party. The proposed scheme does not only satisfy all requirements for multi-server environment but also achieve efficient computation. Besides, our scheme provides complete functionality to suit with the real applications.     

Web服务动态通用客户端的设计与实现

Web Services技术近年来发展迅猛,它基于分布式结构通过Web网络向服务请求者提供服务,并且使用对应的客户端来与服务进行交互,但是这种结构却存在着客户端与Web服务一对一绑定的问题,即调用每个Web服务时都必须使用与服务对应的特定客户端.针对以上问题,提出了一种Web服务动态通用客户端的解决方案,允许服务的主动查找与更新,支持存根的自动生成,从而实现对Web服务的自由调用,使其彻底摆脱一对一模式的束缚,提高实现时的效率和灵活性.     

Using social networks to distort users’ profiles generated by web search engines

The Internet is one of the most important sources of knowledge in the present time. It offers a huge volume of information which grows dramatically every day. Web search engines (e.g. Google, Yahoo…) are widely used to find specific data among that information. However, these useful tools also represent a privacy threat for the users: the web search engines profile them by storing and analyzing all the searches that they have previously submitted. To address this privacy threat, current solutions propose new mechanisms that introduce a high cost in terms of computation and communication. In this paper, we propose a new scheme designed to protect the privacy of the users from a web search engine that tries to profile them. Our system uses social networks to provide a distorted user profile to the web search engine. The proposed protocol submits standard queries to the web search engine; thus it does not require any change in the server side. In addition to that, this scheme does not require the server to collaborate with the users. Our protocol improves the existing solutions in terms of query delay. Besides, the distorted profiles still allow the users to get a proper service from the web search engines.