For many years, the pay-TV system has attracted a lot of users. Users have recently expressed the desire to use mobile TV or mobile payment via anonymous protocols. The mobile users have also received their services over cellular communications networks. Each mobile device receives services from each head end systems. With increasing numbers of users and the expansion of Internet, user’s privacy has become crucial important. When a device leaves the head end system’s range, it must receive services from another head end system. In this paper, we review ’s scheme and we highlight some weaknesses, including privilege insider attack and user traceability attack. Finally, we alleviate the scheme and analyze the alleviated scheme using both heuristic and formal methods.
Encryption-based schemes are most practical classification. This category neither heavy nor light. Thus, are not suitable for weak devices. For example, Yang J-H and Chang proposed @math -based scheme on @math crypto system for remote user authentication @cite_36 . It has some drawbacks such as vulnerability to insider and impersonation attacks @cite_23 . In the hash-based pay-TV system (the next category), we describe Chen's scheme @cite_23 and then analyse it in the section @math . In @math Arshad proposed an efficient scheme @cite_27 based on Wang's scheme @cite_28 . But, there is no bilinear pairing functions and Arshad's scheme is easy to implement on @math boards.
@cite_36 @cite_27 @cite_28 @cite_23
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Summary A mobile pay-TV service is one of the ongoing services of multimedia systems. Designing an efficient mechanism for authentication and key distribution is an important security requirement in mobile pay-TV systems. Until now, many security protocols have been proposed for mobile pay-TV systems. However, the existing protocols for mobile pay-TV systems are vulnerable to various security attacks. Recently, Wang and Qin proposed an authentication scheme for mobile pay-TV systems using bilinear pairing on elliptic curve cryptography. They claimed that their scheme could withstand various attacks. In this paper, we demonstrate that Wang and Qin's scheme is vulnerable to replay attacks and impersonation attacks. Furthermore, we propose a novel security protocol for mobile pay-TV systems using the elliptic curve cryptosystem to overcome the weaknesses of Wang and Qin's scheme. In order to improve the efficiency, the proposed scheme is designed in such a way that needs fewer scalar multiplication operations and does not use bilinear pairing, which is an expensive cryptographic operation. Detailed analyses, including verification using the Automated Validation of Internet Security Protocols and Applications tool and implementation on FPGA, demonstrate that the proposed scheme not only withstands active and passive attacks and provides user anonymity but also has a better performance than Wang and Qin's scheme. In terms of convenience requirements, mobility has been one of the most important services for pay-TV systems. In 2009, Yang and Chang proposed an authentication protocol for mobile devices using elliptic curves cryptography (ECC) and claimed that their mechanism is secure and efficient using in mobile pay-TV systems. In this paper, we demonstrate that their protocol still is insecure for authentication without password protection and performs inefficiently. Therefore, we offer an anonymous authentication protocol (AAP) to solve the performance issue and insecure risks. In addition, we present an analysis of our protocol to show that our protocol suits better for applications with higher security requirements and low power-consuming devices. We present a fully homomorphic encryption scheme that is based solely on the(standard) learning with errors (LWE) assumption. Applying known results on LWE, the security of our scheme is based on the worst-case hardness of short vector problems'' on arbitrary lattices. Our construction improves on previous works in two aspects: We show that somewhat homomorphic'' encryption can be based on LWE, using a new re-linearization technique. In contrast, all previous schemes relied on complexity assumptions related to ideals in various rings. We deviate from the "squashing paradigm'' used in all previous works. We introduce a new dimension-modulus reduction technique, which shortens the cipher texts and reduces the decryption complexity of our scheme, without introducing additional assumptions . Our scheme has very short cipher texts and we therefore use it to construct an asymptotically efficient LWE-based single-server private information retrieval (PIR) protocol. The communication complexity of our protocol (in the public-key model) is @math bits per single-bit query (here, @math is a security parameter). Let ψ be a 2-DNF formula on boolean variables x1,...,xn ∈ 0,1 . We present a homomorphic public key encryption scheme that allows the public evaluation of ψ given an encryption of the variables x1,...,xn. In other words, given the encryption of the bits x1,...,xn, anyone can create the encryption of ψ(x1,...,xn). More generally, we can evaluate quadratic multi-variate polynomials on ciphertexts provided the resulting value falls within a small set. We present a number of applications of the system: In a database of size n, the total communication in the basic step of the Kushilevitz-Ostrovsky PIR protocol is reduced from @math to @math . An efficient election system based on homomorphic encryption where voters do not need to include non-interactive zero knowledge proofs that their ballots are valid. The election system is proved secure without random oracles but still efficient. A protocol for universally verifiable computation.