pay-TV Systems Research Articles

TV personalisation: blending linear and on-demand content in the living room

Nowadays, recommendation systems are everywhere, ranging from e-commerce sites, social networks, all the way to most media streaming services. However, in most pay-TV platforms, these recommendation systems do not usually achieve a suitable level of effectiveness, even when a huge linear and on-demand content catalogue is available. This paper suggests some reasons for that issue, exemplifying some of the shortcomings found in a south European pay-TV system. Driven by the actual perceived limitations, an innovative personalisation system is proposed, and the current state of the prototype development is described. As far as the prototype is concerned, it is already possible to present some identified insights that will be validated in an ongoing field trial and subsequent user evaluation.

TV personalisation: blending linear and on-demand content in the living room

Nowadays, recommendation systems are everywhere, ranging from e-commerce sites, social networks, all the way to most media streaming services. However, in most pay-TV platforms, these recommendation systems do not usually achieve a suitable level of effectiveness, even when a huge linear and on-demand content catalogue is available. This paper suggests some reasons for that issue, exemplifying some of the shortcomings found in a south European pay-TV system. Driven by the actual perceived limitations, an innovative personalisation system is proposed, and the current state of the prototype development is described. As far as the prototype is concerned, it is already possible to present some identified insights that will be validated in an ongoing field trial and subsequent user evaluation.

Correction to: A computationally efficient and scalable key management scheme for access control of media delivery in digital Pay-TV systems

Tables 1, 3, 4, 5, 6, 7, 8 and the body texts in the original publication contain incorrect symbols. The original article article has been corrected.

An Efficient Anonymous Authentication Scheme for Mobile Pay-TV Systems

As a component of mobile communication, the pay-TV system has attracted a lot of attention. By using mobile devices, users interact with the head end system in service providers to acquire TV services. With the growth of mobile users, how to protect the privacy of users while improving efficiency of the network has become an issue worthy of attention. Anonymous authentication schemes for mobile pay-TV systems came into being. In this paper, we analyze the shortcomings of the existing authentication protocol and then propose an improved one, which is secure against stored set attack and user traceability attack. The proposed scheme is proved to be secure. Moreover, our new scheme performs better in efficiency and storage, compared with several other schemes.

A Computationally Efficient and Scalable Key Management Scheme for Access Control of Media Delivery in Digital Pay-TV Systems

In today’s Internet era, group communications in multimedia applications are becoming more and more popular. The issues of controlling illegal access to multimedia contents require efficient and secure mechanisms for distribution of common key called scrambling key or group key. In order to provide secure delivery of multimedia contents in digital pay-TV systems, a large number of keying information messages are exchanged for group key/scrambling key updates in the traditional key distribution schemes. In this paper we propose a Chinese Remainder Theorem (CRT) based key distribution protocol which is highly secure and computationally efficient. The proposed protocol, 1) has drastically reduced the computational complexity of Group Manager (GM) and members for updating the keys, 2) has greatly increased the security by using an additional secret parameter at Group Manager and members areas, 3) can efficiently handle large and dynamically updating groups and, 4) can update the group key in one message, without updating member’s key. With our proposed key distribution scheme, only legal members can access the multimedia contents correctly and the illegal access can be prevented. The proposed scheme is applicable in Conditional Access System (CAS) of digital pay-TV systems without increasing storage and communication overheads on GM and members. The comparative analysis of our proposed scheme with existing schemes in terms of computational cost assures the effectiveness of our scheme. As a proof of concept, we implement our scheme to a decentralized architecture-based key management system and demonstrate that the proposed scheme significantly reduces the computational complexity.

Decentralized Broadcast Encryption Schemes with Constant Size Ciphertext and Fast Decryption

Broadcast encryption ( BE ) allows a sender to encrypt a message to an arbitrary target set of legitimate users and to prevent non-legitimate users from recovering the broadcast information. BE has numerous practical applications such as satellite geolocation systems, file sharing systems, pay-TV systems, e-Health, social networks, cloud storage systems, etc. This paper presents two new decentralized BE schemes. Decentralization means that there is no single authority responsible for generating secret cryptographic keys for system users. Therefore, the scheme eliminates the concern of having a single point of failure as the central authority could be attacked, become malicious, or become unavailable. Recent attacks have shown that the centralized approach could lead to system malfunctioning or to leaking sensitive information. Another achievement of the proposed BE schemes is their performance characteristics that make them suitable for environments with light-weight clients, such as in Internet-of-Things (IoT) applications. The proposed approach improves the performance over existing decentralized BE schemes by simultaneously achieving constant size ciphertext, constant size secret key and fast decryption.

Efficient and Secure Key Management for Conditional Access Systems

In Digital TV service, subscribers get the access of channels of their interest. In conditional access systems (CAS), Control Word is used to deliver the multimedia content to legitimate subscribers securely. In order to update the Control Word frequently, a large number of messages are exchanged in the conventional key distribution systems. This article analyzes the strengths and weaknesses of the existing key distribution protocols for CAS and presents an efficient key distribution protocol for CAS based on Elliptic Curve Cryptography. The proposed protocol minimizes the storage cost and communication cost of subscribers. In addition to this, the proposed protocol facilitates the unrestricted channel package composition and minimum communication cost on rekeying. The proposed protocol also provides perfect forward and backward secrecy. As a result, the proposed protocol is well suited for Pay-TV systems.

Black-Box Accountable Authority Identity-Based Revocation System

Abstract Identity-based revocation system (IBRS) generates the ciphertext with a revoked identity list such that only the non-revoked identities can use their private keys to decrypt this ciphertext. IBRS can be efficiently applied in some practical applications, such as the pay-TV systems when the number of revoked identities are much less than the non-revoked ones. However, since IBRS is based on identity-based cryptography, it also suffers from the inherent key escrow problem where the private key generator (PKG) has full control of each user’s private key. As a consequence, it is hard to judge whether a pirated private key is generated by the PKG or the suspected user. There is no study on IBRS fulfilling accountability in literature to date. In this paper, we introduce the notion of accountable authority IBRS (A-IBRS), which provides accountability in IBRS schemes. In an A-IBRS, the aforementioned problem can be alleviated and resolved. Furthermore, a full black-box A-IBRS can distinguish the creator of a black box between the PKG and the associated user and the dishonest PKG is allowed to access the decryption results of the user private key. We formalize the definition and security models of the full black-box A-IBRS schemes. Then, we present a concrete full black-box A-IBRS scheme with constant-size master public key and private key. Finally, we prove the security of our scheme under the defined security models without random oracle.

A conditional access system with revocation for mobile pay-TV systems revisited

In pay-TV, conditional access systems (CAS) are used by a rights issuer to guarantee that only authorized subscribers gain access to TV channels. A CAS scheme that applies attribute-based access control through attribute-based encryption (ABE) with revocation was proposed by Yeh and Huang (2013) [1]. Yeh and Huang extend an existing ABE scheme with a revocation mechanism. We show that the CAS by Yeh and Huang has security and efficiency problems. Particularly, we show that the revocation mechanism proposed by Yeh and Huang is vulnerable to collusion attacks.

An identity-based encryption technique using subtree for fuzzy user data sharing under cloud computing environment

The advancement of the cloud storage technology opens up a wide range of possibilities for adaptable data sharing. When sharing data to an extensive number of users with fuzzy identities, the data proprietor must use an appropriate identity-based encryption technique that satisfies both efficiency and security prerequisites. Identity-based encryption is a promising possibility to ensure fuzzy user data sharing while meeting the security essentials; however, it may encounter efficiency trouble in multi-receiver settings. Recently, identity-based encryption has received much attention, and most of the research has aimed to apply the technique in real-world systems. A major concern about using identity-based encryption is the safety of the private keys, as disclosure of secret keys requires the reissuing of encryptions already doled out. The capability to minimize the risks associated with key disclosure is particularly important due to the increased use of mobile and unprotected devices. In this article, we shall propose a forward-secure identity-based encryption technique based on subtree for fuzzy user data sharing under cloud computing environment, and we shall demonstrate that the technique is semantically secure against a chosen subtree and chosen ciphertext attack (IND-CST–CCA). In addition, we will show the superiority of our new technique over the currently existing methods in terms of security and the length of public key. Then, we will also discuss the potential of our new technique to be deployed in pay TV systems and grid security.

Efficient and secure conditional access system for pay-TV systems

In Digital TV service, subscribers get the access of channels of their interest. In Conditional Access Systems (CAS), multimedia content is delivered securely using the Control Word (CW). To frequent update of the CW, a large number of messages are exchanged in the conventional key distribution systems. In this paper, a centralized key distribution scheme based on dynamicity of the groups and with freedom of channel package composition is proposed. Scheme has also efficient mechanism of load balancing at Group Controller (GC) side. To speed up the search of the channel package in the existing database, Optimal Binary Search Tree (OBST) data structure and Finite State Machine (FSM) are used. Scheme also provides the efficient leaving and joining mechanism for single user as well as batch users.

Secure and efficient authentication scheme for access control in mobile pay-TV systems

The increasing ubiquity and use of mobile devices enable them to access television programs through mobile pay-TV (MPTV) systems. To achieve secure communication in MPTV systems, authentication schemes for access control in these systems are needed. Recently, a one-to-many authentication (OTMA) scheme that guarantees secure communication in MPTV systems was proposed. However, it was found by other researchers that such a scheme could not resist the impersonation attack and could not provide mutual authentication. As a result, a new OTMA scheme was proposed and it was claimed that OTMA could solve the security weaknesses of the OTMA scheme. We demonstrate that the new OTMA scheme cannot resist the impersonation attack and cannot provide mutual authentication. To mitigate these major security weaknesses, we propose a new OTMA scheme. A security analysis of our proposed OTMA scheme demonstrates that it can overcome the security weaknesses of the previous OTMA scheme and improve its performance.

Secure and efficient authentication scheme for access control in mobile pay-TV systems

The increasing ubiquity and use of mobile devices enable them to access television programs through mobile pay-TV (MPTV) systems. To achieve secure communication in MPTV systems, authentication schemes for access control in these systems are needed. Recently, a one-to-many authentication (OTMA) scheme that guarantees secure communication in MPTV systems was proposed. However, it was found by other researchers that such a scheme could not resist the impersonation attack and could not provide mutual authentication. As a result, a new OTMA scheme was proposed and it was claimed that OTMA could solve the security weaknesses of the OTMA scheme. We demonstrate that the new OTMA scheme cannot resist the impersonation attack and cannot provide mutual authentication. To mitigate these major security weaknesses, we propose a new OTMA scheme. A security analysis of our proposed OTMA scheme demonstrates that it can overcome the security weaknesses of the previous OTMA scheme and improve its performance.

Attacks on “a provably secure and efficient authentication scheme for access control in mobile pay-TV systems”

Mobile pay-TV systems represent an application of important electronic commerce, providing mobile users with the multimedia services. In 2016, Farash and Attari employed the elliptic curves and bilinear pairing technologies to design a one-to-many authentication scheme for mobile pay-TV systems. They claimed that their scheme provides a high level of efficiency and can resist most attacks on mobile pay-TV systems. In this paper, we point out their scheme cannot achieve the fundamental requirement of authentication that is, the mutual authentication. In addition, their scheme still suffers from three security weaknesses.

Revocable hierarchical identity-based encryption over lattice for pay-TV systems

In case the subscriber's certificate may be expired or revealed, a revocable mechanism is needed in a dynamic pay-TV system. Considering the hierarchical structure in this system, a revocable hierarchical identity-based encryption (RHIBE) scheme is a better choice than other schemes. But the well-known RHIBE schemes are constructed on the bilinear pairings. In this paper, two efficient and practical schemes are issued on lattice. Our first scheme is secure against adaptive identity-time attacks in the random oracle (RO) model and the second is against selective identity-time attacks in standard model. The security of both schemes is reduced to the learning with errors (LWE) assumption. In particular, the proposed scheme's basis delegation algorithms are run in the fixed dimension and the ciphertexts are shorter than existing schemes. Both schemes are much more efficient than the known works in terms of computation cost and storage cost.

Revocable hierarchical identity-based encryption over lattice for pay-TV systems

Revocable hierarchical identity-based encryption over lattice for pay-TV systems

An improved one-to-many authentication scheme based on bilinear pairings with provable security for mobile pay-TV systems

In 2012, Wang and Qin proposed an authentication mechanism in order to get access control for mobile pay-TV organization to enhance the Sun and Leu's technique. Wang and Qin declared that their technique satisfies the security expectations or requirements intended for mobile pay-TV system. However, this work indicates that Wang and Qin's scheme suffers from a nontrivial weakness. Successful impersonation attack is easily possible from an adversary who can impersonate mobile set (MS) to cheat the head-end system (HS). An adversary does not even need secret information to do so. As a remedy, we proposed an enhanced authentication technique for mobile pay-TV systems by taking a slight change in Wang and Qin's scheme. The proposed scheme maintains the merits and covers the demerits of the previous schemes.

One-to-many authentication for access control in mobile pay-TV systems

In traditional authentication schemes for access control in mobile pay-TV systems, one-to-one delivery is used, i.e., one authentication message per request is delivered from a head-end system (HES) to a subscriber. The performance of one-to-one delivery for authentication is not satisfactory as it requires frequent operations which results in high bandwidth consumption. To address this issue, one-to-many authentication for access control in mobile pay-TV systems was developed. It requires only one broadcasted authentication message from a HES to subscribers if there are many requests for the same service in a short period of time. However, later it was revealed that the one-to-many authentication scheme was vulnerable to an impersonation attack, i.e., an attacker without any secret key could not only impersonate the mobile set (MS) to the HES but also impersonate the HES to the MS. Then, a new scheme has been recently introduced for secure operations of one-to-many authentication. However, as shown in this paper, the recent work for one-to-many authentication is still vulnerable to the impersonation attack. To mitigate this attack, in this paper, a new scheme for one-to-many authentication using bilinear pairing is proposed that eliminates security weaknesses in the previous work. Results obtained depict that the new improved scheme in this paper provides better performance in terms of computation and communication overheads.

A secure and efficient time-bound hierarchical access control scheme for secure broadcasting

In a time-bound cryptographic key assignment scheme, distinct temporal keys for distinct time periods are assigned to the channels in order to encrypt and decrypt the channels for secure broadcasting. It has numerous applications including the Pay-TV systems. In this paper, we aim to propose a novel time-bound hierarchical access control scheme for secure broadcasting, in which each user needs to store a distinct and unique user's private key, and hence each user in a channel group can subscribe for an individual channel. Our scheme reduces significantly the implementation cost and also improves the computational performance along with extra features. Through the informal and formal security analysis, it is shown that our scheme is secure against various known attacks including the collusion attack. As a result, our scheme is more secure and efficient as compared to other related schemes in the literature.

A secure and efficient time-bound hierarchical access control scheme for secure broadcasting

In a time-bound cryptographic key assignment scheme, distinct temporal keys for distinct time periods are assigned to the channels in order to encrypt and decrypt the channels for secure broadcasting. It has numerous applications including the Pay-TV systems. In this paper, we aim to propose a novel time-bound hierarchical access control scheme for secure broadcasting, in which each user needs to store a distinct and unique user's private key, and hence each user in a channel group can subscribe for an individual channel. Our scheme reduces significantly the implementation cost and also improves the computational performance along with extra features. Through the informal and formal security analysis, it is shown that our scheme is secure against various known attacks including the collusion attack. As a result, our scheme is more secure and efficient as compared to other related schemes in the literature.