Abstract In recent years, network coding has received extensive attention and has been applied to various computer network systems, since it has been mathematically proven to enhance the network robustness and maximize the network throughput. However, it is well-known that network coding is extremely vulnerable to pollution attacks. Certificateless network coding scheme (CLNS) is a recently proposed mechanism to defend against pollution attacks for network coding, which avoids tedious management of certificates and key-escrow attack. Until now, only a few constructions were presented, and more ones should be given so as to enrich this field. In this paper, for the first time, we study the general construction of CLNS from certificateless public auditing protocol (CL-PAP), although the two areas seem to be quite different in their nature and are studied independently. Since there are many candidates of CL-PAPs, we can naturally obtain abundant constructions of CLNSs according to our systematic way. In addition, in order to show the power of the general construction, we also present a concrete implementation given a specific CL-PAP. The performance analysis and experimental results show that the implemented CLNS is competitive in the existing network coding schemes.

Recently, Rabaninejadet al.(2019) proposed an excellent auditing protocol for shared data (CoRPA, for short) [IEEE Trans. Ser. Comp., DOI 10.1109/TSC.2019.2919627], which has many better properties, like the identity-privacy, collusion resistant, efficient user revocation and supporting dynamic update etc. In addition, they also presented the detailed security analysis for CoRPA and described the reduction from the soundness of CoRPA to discrete logarithm assumption. However, in this article, we analyze their original security reduction (to discrete logarithm) and find out that it is incorrect and misleading. That is, the soundness of CoRPA cannot be obtained from the discrete logarithm assumption. Now, we give a new proof for their CoRPA based on the square-CDH assumption, which is also used by them to prove the security of homomorphic proxy re-signature scheme. We also hope the new security proof will provide theoretical guarantee when using CoRPA in practical scenes.

With the advent of the era of big data, the recommendation system has become an effective solution to the problem of information overload. This paper takes the literature data related to the recommendation system theme from 2009 to 2018 and included in the core collection of Web of Science database as the research object, and utilizes bibliometric methods to analyze the theme of recommendation system. To this end, firstly, classify statistics and feature analysis of valid literature data. Secondly, use VOSviewer software to construct various different scientific knowledge graph to discover valuable knowledge. Thirdly, according to keyword co-concurrence graph conclude five main hotspots of current research about recommendation system and discover five main directions that have potential value in research field of recommendation system. Finally, deeply explore five main key issues and propose corresponding solutions.

Homomorphic signature is an extremely important public key authentication technique for network coding to defend against pollution attacks. As a public key cryptographic primitive, it also encounters the same problem of how to confirm the relationship between some public key pk and the identity ID of its owner. In the setting of distributed network coding, the intermediate and destination nodes need to use the public key of source node S to check the validity of vector-signature pairs. Therefore, the binding of S and its corresponding public key becomes crucial. The popular and traditional solution is based on certificates which are issued by a trusted certification authority (CA) center. However, the generation and management of certificates is extremely cumbersome. Hence, in recent work, Lin et al. proposed a new notion of identity-based homomorphic signature, which intends to avoid using certificates. But the key escrow problem is inevitable for identity-based primitives. In this article, we propose another new notion (for network coding): certificateless homomorphic signature (CLHS), which is a compromise for the above two techniques. In particular, we first describe the definition and security model of certificateless homomorphic signature. Then based on bilinear map and the computational Diffie-Hellman (CDH) assumption, give a concrete implementation and detailedly analyze its security. Finally, performance analysis illustrates that our construction is practical.

In 2014, Wu et al. proposed a tag encoding scheme, named KEPTE, to protect network coding against pollution attack. They also carefully analyzed the security of KEPTE based on the transmission of a data file through their key-pre-distributed network. In this article, we point out that their security analysis only holds for single data file transmitted in this network. If multiple files are multicasted though it, then any adversary may completely recover source node's signing key. A concrete example says that, after pre-distributing 90 keys to all the nodes in the network, it only allows to securely transmit (at most) 3 data files. More importantly, this scheme is completely insecure in standard security model for network model since the adversary is allowed to make polynomial times queries on any data files of its choice before outputting its final forgery. Finally, we also propose a twisted KEPTE scheme that is secure against any eavesdropping adversary no matter how many data files it has queried.