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Mobile healthcare (mHealth) enables people to collect and share their personal health records (PHRs) and gain rapid medical treatment via mobile 5G-enabled Industrial Internet of Things (IIoT) devices, which also brings the challenge of keeping the PHRs confidentiality and preventing unauthorized access. By the emerging Ciphertext-Policy Attribute-based Encryption (CP-ABE), the PHR owner can encrypt his PHR data under self-defined access policies. However, existing CP-ABE schemes are suffering from either heavy computation cost and storage overhead or traitor tracing and direct revocation. In this paper, we propose an efficient, traceable and revocable access control scheme named TRAC for mHealth in 5G-enabled IIoT. In TRAC, the ciphertext is composed of the attribute-relevant ciphertext encrypted under an AND-gate access structure and the identity-relevant ciphertext associated with some potential receivers. The malicious user who leaks his/her privilege to unauthorized entities will be precisely tracked and added in the revocation list, by which the cloud server can update the identity-relevant ciphertext by itself. The length of final ciphertext and the time of bilinear pairing operations used in decryption are constant. The security analysis and performance evaluation indicate the security, efficiency and practicality of TRAC.

The wide adoption of cloud greatly facilitates the sharing of explosively generated media content today, yet deprives content providers’ direct control over the outsourced media content. Thus, it is pivotal to build an encrypted cloud media center where only authorized access is allowed. Enforcing access control alone, however, cannot fully protect content providers’ interests, as authorized users may later become traitors that illegally redistribute media content to the public. Such realistic threat should have been seriously treated yet is largely overlooked in the literature. In this paper, we initiate the first study on secure media sharing with fair traitor tracing in the encrypted cloud media center, through a new marriage of proxy re-encryption (for secure media sharing) and fair watermarking (for fair traitor tracing). Our key insight is to fully leverage the homomorphic properties residing in proxy re-encryption to embrace operations in fair watermarking. Two protocols are proposed for different application scenarios. We also provide complexity analysis for performance, showing that our work can also be treated as secure outsourcing of fair watermarking, and thus kills two birds with one stone. We thoroughly analyze the security strengths and conduct extensive experiments to validate the effectiveness of our design.

Traitor tracing scheme is a paradigm to classify the users who illegal use of their decryption keys in cryptosystems. In the ciphertext-policy attribute-based cryptosystem, the decryption key usually contains the users’ attributes, while the real identities are hidden. The decryption key with hidden identities enables malicious users to intentionally leak decryption keys or embed the decryption keys in the decryption device to gain illegal profits with a little risk of being discovered. To mitigate this problem, the concept of blackbox traceability in the ciphertext-policy attribute-based scheme was proposed to identify the malicious user via observing the I/O streams of the decryption device. However, current solutions with blackbox traceability are impractical since either the composite-order group or the linear complexity of system users is required. In this article, we proposed a secure ciphertext-policy attribute-based set encryption scheme with the short decryption key. The proposed scheme bases on the prime-order group to improve computational performances and aggregates multiple attributes into a constant-size attribute set to reduce the costs of communication overheads. By applying our proposed scheme with fingerprint codes, we then give an instantiation of the ciphertext-policy attribute-based scheme with blackbox traceability. Our scheme is provably secure under various q-type assumptions.

Fine-grained searching is an important feature in multi-user cloud environment and a combination of attribute-based encryption (ABE) and searchable encryption (SE) is used to facilitate it. This combination provides a powerful tool where multiple data owners can share their data with multiple data users in an independent and differential manner. In this article, the authors have used key-policy design framework of attribute-based encryption to construct the multi-keyword search scheme where access rights assigned to a data user are associated with his/her secret key. This leads to a situation where a data user can abuse his secret key to distribute it illegally to the unauthorized users to perform search over the shared data which is not intended for him/her. Therefore, to track such kind of key abusers the authors have embedded an extra functionality of tracing the traitors. For this purpose, each user is assigned a unique identity in the form of binary string where each bit represents an attribute related to his identity. In addition to the normal attributes, the access structure of a user also possesses identity-related attributes which are hidden from the user along with some normal attributes. Hence, the proposed scheme supports partial anonymity. Further, in the event of user revocation the proposed scheme efficiently handles the system update process by delegating the computationally intensive tasks to the cloud server. Finally, the proposed scheme is proved secure under Decisional Bilinear Diffie-Hellman (DBDH) assumption and decision linear assumption in the selective security model.

The use of digital watermarking to secure the content of database systems is a new research direction in information security. Until now, the majority of the work has been based on image, video and audio. However, because of the growing use of relational database systems, database watermarking has become a research subject. Which addresses the legal issue of database system copyright protection. In this paper, we have focused on the review of four relational database watermarking techniques proposed by researchers [R. Agarwal & Jerry Kiernan, ZHU Qin, Brijesh B. Mehta, A. Al-Haj and Ali Hamadou]. The security of relational databases has been a great concern since the expanded use of these data over the Internet. Digital watermarking for relational databases emerged as a candidate solution to provide copyright protection, tamper detection, traitor tracing and maintaining integrity of relational data.

Securing multimedia content and preventing it from being maliciously manipulated has developed at a rapid pace, and researchers have been studying the traitor tracing as an appropriate solution. This approach consists in retrieving back the actors who contributed to the construction of an illegal release of a multimedia product. It includes two major steps which are the fingerprinting step and the tracing one. The fingerprinting step relies on the watermarking technique whereas the efficiency of the tracing scheme depends on several requirements: the robustness of the watermarking technique, the type of the media content, and even the computational complexity. In this paper, we propose a new collusion-secure fingerprinting scheme for 3D videos. It has essentially a twofold purpose: at a first step, we propose to embed the watermark in the video copy by applying a standard Least Significant Bit (LSB) substitution to all the frames of both the 2D video and the depth map components in order to ensure simultaneously and independently the protection of these two parts. In the second step, we apply the tracing process whose target is the identification of eventual colluders by extracting the hidden identifier from the suspicious video and analyse it. Experimental assessments show that the proposed scheme provides interesting results in terms of speed and tracing accuracy constraints.

Aggregate signature schemes enable us to aggregate multiple signatures into a single short signature. One of its typical applications is sensor networks, where a large number of users and devices measure their environments, create signatures to ensure the integrity of the measurements, and transmit their signed data. However, if an invalid signature is mixed into aggregation, the aggregate signature becomes invalid, thus if an aggregate signature is invalid, it is necessary to identify the invalid signature. Furthermore, we need to deal with a situation where an invalid sensor generates invalid signatures probabilistically. In this paper, we introduce a model of aggregate signature schemes with interactive tracing functionality that captures such a situation, and define its functional and security requirements and propose aggregate signature schemes that can identify all rogue sensors. More concretely, based on the idea of Dynamic Traitor Tracing, we can trace rogue sensors dynamically and incrementally, and eventually identify all rogue sensors of generating invalid signatures even if the rogue sensors adaptively collude. In addition, the efficiency of our proposed method is also sufficiently practical.

Attribute-based encryption received widespread attention as soon as it proposes. However, due to its specific characteristics, the attribute-based access control method is not flexible enough in actual operation. In addition, since access authorities are determined according to users' attributes, users sharing the same attributes are difficult to distinguish. Once a malicious user makes illicit gains by their decryption authorities, it is difficult to trace specific users. This paper follows the practical demand to propose a more flexible key-policy attribute-based encryption scheme with black-box traceability. The scheme has a constant number of constant parameters which can be utilized to construct attribute-related parameters flexibly, and the method of traitor tracing in broadcast encryption is introduced to achieve effective malicious user tracing. In addition, the security and feasibility can be proved by the security proofs and performance evaluation in this paper.

Cloud-based deep learning (DL) solutions have been widely used in applications ranging from image recognition to speech recognition. Meanwhile, as commercial software and services, such solutions have raised the need for intellectual property rights protection of the underlying DL models. Watermarking is the mainstream of existing solutions to address this concern, by primarily embedding pre-defined secrets in a model's training process. However, existing efforts almost exclusively focus on detecting whether a target model is pirated, without considering traitor tracing. In this paper, we present SecureMark_DL, which enables a model owner to embed a unique fingerprint for every customer within parameters of a DL model, extract and verify the fingerprint from a pirated model, and hence trace the rogue customer who illegally distributed his model for profits. We demonstrate that SecureMark_DL is robust against various attacks including fingerprints collusion and network transformation (e.g., model compression and model fine-tuning). Extensive experiments conducted on MNIST and CIFAR10 datasets, as well as various types of deep neural network show the superiority of SecureMark_DL in terms of training accuracy and robustness against various types of attacks.

E-healthcare cloud remarkably facilitates patients to outsource their electronic health record (EHR) to achieve large-scale information sharing in real-time for improving the efficiency of diagnosis and treatment. Unfortunately, compared with other outsourced data, EHR contains more personal privacy, which makes it more preferred by the adversaries. Besides, in the e-healthcare cloud, there may exist malicious users who deliberately disclose their access privileges to obtain financial benefits. In this paper, we propose a fine-grained EHR sharing scheme in e-healthcare cloud with hidden policy and traceability. Specifically, we present a new black-box traitor tracing scheme based on partial policy hiding attribute-based encryption and it performs fine-grained access control on the encrypted EHR, which not only prevents privacy leakage from access policy but also effectively track malicious users who leak decryption privileges to construct a black-box. Our scheme is proved to be fully secure under the standard model. Performance analysis shows that the scheme can achieve the design goals in terms of storage and computation overhead. In the meantime, it is more efficient than the existing schemes under the composite order group.

Recently, many enterprises have moved their data into the cloud by using file syncing and sharing (FSS) services, which have been deployed for mobile users. However, Bring-Your-Own-Device (BYOD) solutions for increasingly deployed mobile devices have also in fact raised a new challenge for how to prevent users from abusing the FSS service. In this paper, we address this issue by using a new system model involving anomaly detection, tracing, and revocation approaches. The presented solution applies a new threshold public key based cryptosystem, called partially-ordered hierarchical encryption (PHE), which implements a partial-order key hierarchy and it is similar to role hierarchy widely used in RBAC. PHE provides two main security mechanisms, i.e., traitor tracing and key revocation, which can greatly improve the efficiency compared to previous approaches. The security and performance analysis shows that PHE is a provably secure threshold encryption and provides following salient management and performance benefits: it can promise to efficiently trace all possible traitor coalitions and support public revocation not only for the users but for the specified groups.

Ciphertext-policy attribute-based encryption (CP-ABE) has been proposed to enable fine-grained access control on encrypted data for cloud storage service. In the context of CP-ABE, since the decryption privilege is shared by multiple users who have the same attributes, it is difficult to identify the original key owner when given an exposed key. This leaves the malicious cloud users a chance to leak their access credentials to outsourced data in clouds for profits without the risk of being caught, which severely damages data security. To address this problem, we add the property of traceability to the conventional CP-ABE. To catch people leaking their access credentials to outsourced data in clouds for profits effectively, in this paper, we first propose two kinds of non-interactive commitments for traitor tracing. Then we present a fully secure traceable CP-ABE system for cloud storage service from the proposed commitment. Our proposed commitments for traitor tracing may be of independent interest, as they are both pairing-friendly and homomorphic. We also provide extensive experimental results to confirm the feasibility and efficiency of the proposed solution.

Anonymous authentication schemes, mostly based on the notion of group signatures, allow a group member to obtain membership from a server and gain access rights if the member can prove their authenticity to the verifier. However, existing authentication schemes are impractical because they neglect to provide an exclusive verification of the blacklist. In addition, the schemes are unaware of malicious members who are involved in privilege transferring. In this paper, a novel membership authentication scheme providing detection of membership transfer and proof of membership exclusiveness to the blacklist is proposed.

In Fog Computing, fragile connection between Fog and Cloud causes problems of the authentication and authorization. Recently, Stojmenovic, Wen, Huang and Luan introduced a potential solution by adopting the concept of Stand-Alone Authentication (SAA) and equipped it with Attribute-based encryption (ABE) for its security in a large and dynamic information system. In such a system, a users access right can be described as a set of attributes linking to his/her private key. In this paper, we note that if a user can generate a new private key for a portion of his/her access right, this could potentially lead to some undesirable situations, which violates the access control policy. Interestingly, to date, there is no work that looks into this matter in detail nor addresses it. We point out that this is a property that exists in ABE systems, which we refer to key-delegation abuse. ABE systems that suffer from key-delegation abuse will hinder the adoption of these systems in practice. In this work, for the first time in the literature, we address the key-delegation abuse problem in Ciphertext-policy Attribute-based Encryption (CP-ABE) systems. We introduce a new mechanism to enhance CP-ABE schemes that provide protections against this key-delegation abuse issue. We formalize the security requirements for such a property, and subsequently construct a CP-ABE scheme that satisfies the new security requirements. We also present an application of our scheme to a traceable CP-ABE, where the traitors, i.e. the users who have leaked their keys, can be traced. The property of key-delegation abuse in ABE system is investigated.A provably secure CP-ABE scheme against key-delegation abuse is proposed.A new security game model against key-delegation abuse is introduced.The new feature of proposed CP-ABE scheme is proved in generic group model.An application of traitor tracing CP-ABE scheme is also presented.

Image phylogeny is the problem of reconstructing the structure that represents the history of generation of semantically similar images (e.g., near-duplicate images). Typical image phylogeny approaches break the problem into two steps: (1) estimating the dissimilarity between each pair of images and (2) reconstructing the phylogeny structure. Given that the dissimilarity calculation directly impacts the phylogeny reconstruction, in this paper, we propose new approaches to the standard formulation of the dissimilarity measure employed in image phylogeny, aiming at improving the reconstruction of the tree structure that represents the generational relationships between semantically similar images. These new formulations exploit a different method of color adjustment, local gradients to estimate pixel differences and mutual information as a similarity measure. The results obtained with the proposed formulation remarkably outperform the existing counterparts in the literature, allowing a much better analysis of the kinship relationships in a set of images, allowing for more accurate deployment of phylogeny solutions to tackle traitor tracing, copyright enforcement and digital forensics problems.

Data encryption and signature technique can provide secure data protection and verification during data transmission. A data owner can choose to generate a legal signature first, then encrypt it before data sharing. However, the traditional sign-then-encrypt method not only occupies much more computation resources on digital devices, but also brings about high computation cost to the whole communication systems when data verification and key updating happens. In this paper, we utilize CP-ABE and ABS to propose a CP-ABSC scheme, which reduces the calculation burden for users in multi-party communication scenario. By security analysis, our scheme is demonstrated to realize confidentiality, unforgeability with resistance of collusion attack and traitor tracing.

In this work, we show how to use indistinguishability obfuscation (iO) to build multiparty key exchange, efficient broadcast encryption, and efficient traitor tracing. Our schemes enjoy several interesting properties that have not been achievable before: Our multiparty non-interactive key exchange protocol does not require a trusted setup. Moreover, the size of the published value from each user is independent of the total number of users. Our broadcast encryption schemes support distributed setup, where users choose their own secret keys rather than be given secret keys by a trusted entity. The broadcast ciphertext size is independent of the number of users. Our traitor tracing system is fully collusion resistant with short ciphertexts, secret keys, and public key. Ciphertext size is logarithmic in the number of users and secret key size is independent of the number of users. Our public key size is polylogarithmic in the number of users. The recent functional encryption system of Garg, Gentry, Halevi, Raykova, Sahai, and Waters also leads to a traitor tracing scheme with similar ciphertext and secret key size, but the construction in this paper is simpler and more direct. These constructions resolve an open problem relating to differential privacy. Generalizing our traitor tracing system gives a private broadcast encryption scheme (where broadcast ciphertexts reveal minimal information about the recipient set) with optimal size ciphertext. Several of our proofs of security introduce new tools for proving security using indistinguishability obfuscation.

The currently-emerging technology demands sharing of data using various channels via the Internet, disks, etc. Some recipients of this data can also become traitors by leaking the important data. As a result, the data breaches due to data leakage are also increasing. These breaches include unauthorized distribution, duplication, and sale. The identification of a guilty agent responsible for such breaches is important for: (i) punishing the culprit, and (ii) preventing the innocent user from accusation and punishment. Fingerprinting techniques provide a mechanism for classifying the guilty agent from multiple recipients and also help to prevent the innocent user from being accused of the data breach. To those ends, in this paper, a novel fingerprinting framework has been proposed using a biometric feature as a digital mark (signature). The use of machine learning has also been introduced to make this framework intelligent, particularly for preserving the data usability. An attack channel has also been used to evaluate the robustness of the proposed scheme. The experimental study was also conducted to demonstrate that the proposed technique is robust against several malicious attacks, such as subset selection attacks, mix and match attacks, collusion attacks, deletion attacks, insertion attacks, and alteration attacks.

A traitor tracing scheme is a public key encryption scheme for which there are many secret decryption keys. Any of these keys can decrypt a ciphertext; moreover, even if a coalition of users collude, put together their decryption keys and attempt to create a new decryption key, there is an efficient algorithm to trace the new key to at least one the colluders.

A blackbox traceable Attribute-Based Encryption (ABE) can identify a malicious user called traitor, which created a decryption box with respect to an attribute set (respectively, access policy), out of all the users who share the same attribute set (respectively, access policy). However, none of the existing traceable ABE schemes can also support revocation and large attribute universe, that is, being able to revoke compromised keys, and can take an exponentially large number of attributes. In this paper, we formalize the definitions and security models, and propose constructions of both Ciphertext-Policy ABE and Key-Policy ABE that support (i) public and fully collusion-resistant blackbox traceability, (ii) revocation, (iii) large universe and (iv) any monotonic access structures as policies (i.e. high expressivity). We also show that the schemes are secure and blackbox traceable in the standard model against selective adversaries.

A public key trace and revoke scheme combines the functionality of broadcast encryption with the capability of traitor tracing. In Asiacrypt 2003, Kim, Hwang and Lee proposed a public key trace and revoke scheme (referred to as KHL scheme), and gave the security proof to support that their scheme is z-resilient against adaptive chosen-ciphertext attacks, in which the adversary is allowed to adaptively issue decryption queries as well as adaptively corrupt up to z users. In the passed ten years, KHL scheme has been believed as one of the most efficient public key trace and revoke schemes with z-resilience against adaptive chosen-ciphertext attacks under the well-studied DDH assumption. However, in this paper, by giving a concrete attack, we indicate that KHL scheme is actually not secure against adaptive chosen-ciphertexts, even without corruption of any user. We then identify the flaws in the security proof for KHL-scheme, and discuss the consequences of the attack.

In cloud storage systems, data outsourcing and untrusted service providers make data-access control become a challenging issue because traditional technologies always consider service providers as a fully trusted party. Ciphertext-policy attribute-based encryption CP-ABE shows particular advantages in this setting because this encryption gives the data owner a direct control on data-access policies. However, malicious users in traditional CP-ABE systems may leak their decryption keys in the form of a decryption device/blackbox with little risk of getting caught because no one including the key authorities can reveal them. This issue has become a major practicality concern in many data outsourcing applications e.g., financial and healthcare systems where the preservation of privacy with regard to sensitive data is critical. To address this problem, blackbox traceable CP-ABE leveraged the "traitor tracing" property of broadcast encryption to identify these malicious users. However, the size of the keys and ciphertexts in the blackbox traceable CP-ABE depends on the number of users. In this paper, we introduce an accumulator-based encryption ACC-ENC, which can be integrated with conventional non-traceable CP-ABE-based data-access control to achieve an additional blackbox traceability feature without sacrificing performance just adds O1 elements to the ciphertext and the public key. We first formally define the model of ACC-ENC and present a concrete construction that is proven fully secure; then, we illustrate applying ACC-ENC to obtain CP-ABE-based data-access control with blackbox traceability for cloud storage. Performance evaluation shows that additional computation costs of the proposition are very low compared to the original scheme. Copyright © 2015 John Wiley & Sons, Ltd.

Buyer-seller watermarking protocols, combining digital watermarking and cryptographic tools, have become a feasible technique to guarantee piracy tracing. For securing health information management, watermarking protocols may be introduced to solve the problem of traitor tracing, i.e., tracing the physician who illegally discloses the patient's health information. As a physician asks the health information system (HIS) for the intended patient's health information, the relationship between the physician and HIS is similar to that between buyer and seller. By watermarking protocol, it can prevent physician from illegally distributing the patient's health information over telemedicine environments in case remote physician and local physician exchange the patient's health information and diagnosis views. While unauthorized health information is found, HIS can trace and accuse some physician who illegally releases the sensitive patient's health information. However, buyer-seller protocols mentioned above cannot be applied to telemedicine systems directly because there is more than one physician involved. This paper proposes a multi-watermarking protocol to solve this problem, in which a well-defined single watermarking protocol is extended to form a novel multi-watermarking protocol. In addition, the proposed protocol adopts symmetric cryptosystem into watermark embedding so that the computation cost is lower than the protocols based on public key operation.

In this paper the execution time is less when compared to previous algorithm. And also it provide security between the merchant and buyer The traitor tracing protocol is used to detect the illegal transaction. Here we used fingerprinting solution to avoid illegal redistribution of multimedia contents. Here we convert the multimedia video file into image then encrypting the image after the encrypted image will be transferred from merchant to buyer. The buyer receives the copyright protection from merchant, he decrypts the image then converts it into video. After that, the copyright protection of file is transferred to child buyer. Then tracing traitor protocol is used to checks the fingerprints for merchant to buyer and buyer to child buyer. Traitor tracing protocol is used to detect the illegal transaction of the content. The Blowfish algorithm is used to encrypt and decrypt the multimedia files. Finally we detect the performance of our work based on efficiency, accuracy and we achieve security.

Ciphertext-policy attribute-based encryption (CP-ABE) enables fine-grained access control to the encrypted data for commercial applications. There has been significant progress in CP-ABE over the recent years because of two properties called traceability and large universe, greatly enriching the commercial applications of CP-ABE. Traceability is the ability of ABE to trace the malicious users or traitors who intentionally leak the partial or modified decryption keys for profits. Nevertheless, due to the nature of CP-ABE, it is difficult to identify the original key owner from an exposed key since the decryption privilege is shared by multiple users who have the same attributes. On the other hand, the property of large universe in ABE enlarges the practical applications by supporting flexible number of attributes. Several systems have been proposed to obtain either of the above properties. However, none of them achieve the two properties simultaneously in practice, which limits the commercial applications of CP-ABE to a certain extent. In this paper, we propose two practical large universe CP-ABE systems supporting white-box traceability. Compared with existing systems, both the two proposed systems have two advantages: 1) the number of attributes is not polynomially bounded and 2) malicious users who leak their decryption keys could be traced. Moreover, another remarkable advantage of the second proposed system is that the storage overhead for traitor tracing is constant, which are suitable for commercial applications.

This paper addresses the problem of unauthorized redistribution of multimedia content by malicious users (pirates). The solution proposed here is a new joint fingerprinting and decryption method which meets the requirements for both imperceptibility and robustness of fingerprints and scalability in terms of design and distribution of fingerprinted multimedia content. The proposed method uses a simple block cipher based on matrix multiplication to encrypt images which are then sent to all users via multicast transmission. Individual decryption keys are designed depending on the users' fingerprints so that a different fingerprint will be introduced into the image during decryption for each unique decryption key. Encryption and fingerprinting are performed on DCT coefficients, which results in high robustness against compression, low-pass filtering, scaling, etc. The experimental results show that the proposed method is robust against collusion attacks and compression. A new joint fingerprinting and decryption method has been proposed.The method uses a matrix-based cipher for fingerprinting on the receiver side.Imperceptibility of embedded fingerprints has been achieved.Embedded fingerprints have been tested against collusion attacks and compression.The proposed fingerprinting method has high robustness against collusion attacks.

Anonymous fingerprint has been suggested as a convenient solution for the legal distribution of multimedia contents with copyright protection whilst preserving the privacy of buyers, whose identities are only revealed in case of illegal re-distribution. However, most of the existing anonymous fingerprinting protocols are impractical for two main reasons: 1) the use of complex time-consuming protocols and/or homomorphic encryption of the content, and 2) a unicast approach for distribution that does not scale for a large number of buyers. This paper stems from a previous proposal of recombined fingerprints which overcomes some of these drawbacks. However, the recombined fingerprint approach requires a complex graph search for traitor tracing, which needs the participation of other buyers, and honest proxies in its P2P distribution scenario. This paper focuses on removing these disadvantages resulting in an efficient, scalable, privacy-preserving and P2P-based fingerprinting system.

Now a days we are sharing large number of multimedia contents along with copyright protection. Assurance of proprietorship is needed because large increment in duplicates and to reduce illegal redistribution. Fingerprint mechanism is categorized in to three symmetric, asymmetric and anonymous. They have used traitor tracing protocol to identify illegal re-distributor. It uses complex graph to search for traitor tracing, and also it requires the participation of several honest buyers and anonymous communication through proxies. Drawbacks considered are justified by maintaining the transaction monitor and Symmetric Keys. Transaction monitor stores an encrypted version of the fingerprint for each buyer to trace an illegal re-distributor in the tracing protocol. Symmetric keys are maintained in the Data base and these Keys are not transmitted through proxies. For this all the user ought to be online. It is efficient and scalable fingerprint mechanism for p2p based fingerprinting system.

Part 7: Various Aspects of Computer Security; International audience; In 2002, Mitsunari, Sakai and Kasahara formulated the Collusion Attack Algorithm with k traitors (known as k-CAA problem) and used it to develop the first traitor tracing scheme based on the bilinear pairings. Traitor tracing scheme is needed to discourage legitimate subscribers from sharing their secret keys to construct pirate decoders. In this paper, we propose a first signature scheme (IE-CBS-kCAA) based on k-CAA problem, which belongs to the fourth category of PKC schemes: the public key cryptography schemes based on an implicit and explicit certificates. The security analysis proves that our IE-CBS-kCAA scheme is secure against two game attacks in the random oracle model. The security is closely related to the difficulty of solving the modified k-CAA and discrete logarithm problems.

The easiness of using and manipulating digital media content has a volte face. In fact, although average users can simply be familiar with some manipulations such as a simple duplication, these manipulations can be dangerous with dishonest users whose target is illegal. Manipulating and duplicating digital media content via the Internet and Peer to Peer networks is available even to average users but can be used to unauthorized purposes with dishonest customers. Henceforth, facing the loss caused by unauthorized treatments and protecting the digital content become challenging to the media industry and research has led to different mechanisms of digital content protection. The aim of the multimedia distribution platforms, even Video on demand platforms, is to propose a suitable structure to the embedded fingerprints to ensure an efficient and fast tracing process in multimedia distribution platforms involving great number of users. The Tardos code has been the most popular tracing code due to its efficient tracing detection performance. One main challenge of the existing Tardos-based tracing approaches was to face the decoding complexity and the computational costs of the tracing process.

International audience; The multimedia traitor tracing field involves the embedding of a collusion secure fingerprint in the host signal to retrieve and prevent any multimedia content fraud. Trendy work aims at providing a tracing system which offers a good protection of the digital content and an efficient tracing process. These challenges depend on reducing the length of the embedded fingerprint and the complexity of the accusation process. Furthermore, addressing these issues becomes more and more relevant in media distribution applications involving an important number of users. In this paper, we propose a secure fingerprinting system based on a two-stage tracing strategy which combines two probabilistic tracing codes: Boneh Shaw with replication scheme and Tardos codes. This strategy is applied to a multilevel hierarchical fingerprint which is then embedded using a DCT-based audio watermarking technique. By taking the advantage of grouping users and applying a weight-based tracing process, the proposed fingerprinting system offers to reduce efficiently the computational costs of the tracing time. It has also a good robustness to different types of attacks. We have carried out different tests to evaluate the performance of the system in terms of robustness and imperceptibility. The experimental results show that the proposed fingerprinting system provides a suitable solution to the the infringement copyright problem in multimedia distribution platforms by reducing significantly the users’ retrieval space and performing good detection results in a reduced time.

In Eurocrypt 2009, Wu et al. introduced the notion of asymmetric group key agreement ASGKA and presented a generic construction of ASGKA protocols with one communication round. Most of ASGKA protocols are designed under that generic construction. In asymmetric group key agreement protocols, users obtain different decryption keys. Any subset of group members may collude to construct pirate decryption keys, which are different from those of colluders but can correctly decrypt ciphertexts. If a pirate decryption box is found, it is possible to find traitors since their decryption keys are related to their identities. In this paper, a collusion attack on the generic construction of ASGKA by Wu et al. is proposed. It is formally proved that each of colluders participating in the proposed collusion attack is unable to be traced. The attack is additionally applied to a concrete protocol to exemplify the collusion attack. Copyright © 2014 John Wiley & Sons, Ltd.

In broadcast encryption system certain users may leak their decryption keys to build pirate decoders, so traitor tracing is quite necessary. There exist many codes based traitor tracing schemes. As pointed out by Billet and Phan in ICITS 2008, these schemes lack revocation ability. The ability of revocation can disable identified malicious users and users who fail to fulfill the payments, so that the broadcast encryption system can be more practical. Recently, Zhao and Li presented a construction of codes based tracing and revoking scheme which achieves user revocation as well as traitor tracing. However, their scheme is only secure against chosen plaintext attacks under selective-adversary model with random oracle. In this paper, we obtain a new construction of codes based tracing and revoking scheme which is proved secure against chosen ciphertext attacks under adaptive-adversary model without random oracle. Our idea is to insert codeword into Boneh and Hamburgs identity based broadcast encryption scheme to retain the ability of user revocation and use Boneh and Naors method to trace traitors. Our fully secure scheme is roughly as efficient as Zhao and Lis scheme while the security is enhanced.

For the traitor tracing of multimedia content, this paper presents the classification algorithm of XOR collusion attack types using hamming distance, which applies to the colluded fingerprinting codes. The conventional traitor decision hinges on the colluded fingerprinting code used by a correlation coefficient, but the proposed scheme uses hamming distance. While XOR collusion attack employing a correlation coefficient is impossible to trace the traitors about 50% colluders due to a serious XOR linear problem, our method improves the performance of traceability to trace at least 1 traitor using hamming distance, and thus, the functional behavior of the proposed traitor traceability is coincided with Probability Scheme.

The digital rights management (DRM) techniques are very important in the fields of multimedia security. The major areas of multimedia data security includes secrecy, ownership protection and traitor tracing. Even though, a number of encryption techniques were developed for multimedia encryption, most of them are vulnerable to several types of attacks. Hence, an encryption system having better security with minimal level of system complexity is an important requirement in multimedia security. In this paper, the cryptanalysis of two arithmetic coding based encryption techniques (randomized arithmetic coding(RAC) and chaotic binary arithmetic coding(CBAC))were proposed and proved that these schemes are vulnerable to known-plaintext attack. Then, a modified secure arithmetic coding based encryption system by providing block-wise shuffling of DCT matrix prior to the CBAC stage (block-shuffled CBAC)is proposed to improve the overall security of the system. In order to provide content protection after decryption for the proposed scheme, the joint fingerprinting and decryption (JFD) technique is provided at the receiver stage. Finally, this idea of image encryption has been extended to video (H.264 coding standard). Here, the work is based on a correlation preserving sorting algorithm whereby a comparable compression performance is obtained in addition to the high level of security. The proposed systems are tested against various types of attacks and it has been proved that these methods are able to withstand various types of attacks with good compression performance and minimal level of increase in system complexity.

Background Attribute based encryption has been widely applied for secure data protection in PHR systems. However, since different users may share the same attributes in the system, a user may leaks his private key for illegal data sharing without being detected. This will add more threat to the private data stored in PHR system. Finding To help users achieve higher efficiency and more secure data sharing in mobile PHR system, based on previous works, we study the traitor tracing mechanism in attribute based cryptosystem and propose a high efficient attribute based encryption with user accountability in mobile PHR system. If a malicious PHR user exposes his private key for illegal data sharing, his identity can be accurately pinpointed by the system manager. During the whole process of data sharing, no bilinear pairing operations are needed, hence this will the mobile terminal devices from heavy computation burden. Conclusion As a further study, in this short report, we show that using a novel attribute based encryption with user accountability can help users achieve better efficiency and more secure data sharing in mobile PHR system.

Ciphertext-policy attribute-based encryption (CP-ABE) is a highly promising solution for cloud computing, which has been widely applied to provide fine-grained access control in cloud storage services recently. However, for CP-ABE based cloud storage systems, if a decryption device appears on eBay described and advertised to be able to decrypt any ciphertexts with policies satisfied by an attribute set or even with a specific access policy only, no one can trace the malicious user(s) who built such a decryption device using their private key(s). This has been known as a major obstacle to deploying CP-ABE systems in real-world commercial applications. Due to the one-to-many encryption mechanism of CP-ABE, the same decryption privilege is shared by multiple users who have the same attributes. It is difficult to identity the malicious user(s) who built such a decryption device. To track people selling decryption devices on eBay efficiently, in this paper, we develop a new methodology for constructing traitor tracing functionality, and present the first black-box traceable CP-ABE (BT-CP-ABE) with short ciphertexts which are independent of the number of users \(\mathcal {N}\). The black-box traceability is public, fully collusion-resistant, and adaptively traceable against both key-like decryption black-box and policy-specific decryption black-box.

The objective of traitor tracing technique is to enable a broadcaster to identify illegal users from secret keys issued to them. In a broadcast encryption scheme, although a broadcaster can identify a traitor when a secret key is leaked, the decrypted copy is not protected from illegal distribution. In the fingerprinting scheme, a broadcaster can trace illegal users from a pirated copy because each user purchases the copy watermarked by his own fingerprint. However, the transaction to distribute the copy is one-to-one. In this paper, we have proposed a broadcast-type fingerprinting scheme such that only authorized users who have own decryption key can obtain the fingerprinted copy.

In a traitor tracing scheme, each user is given a different decryption key. A content distributor can encrypt digital content using a public encryption key and each user in the system can decrypt it using her decryption key. Even if a coalition of users combines their decryption keys and constructs some "pirate decoder" that is capable of decrypting the content, there is a public tracing algorithm that is guaranteed to recover the identity of at least one of the users in the coalition given black-box access to such decoder. In prior solutions, the users are indexed by numbers $$1,\ldots ,N$$1,',N and the tracing algorithm recovers the index i of a user in a coalition. Such solutions implicitly require the content distributor to keep a record that associates each index i with the actual identifying information for the corresponding user e.g., name, address, etc. in order to ensure accountability. In this work, we construct traitor tracing schemes where all of the identifying information about the user can be embedded directly into the user's key and recovered by the tracing algorithm. In particular, the content distributor does not need to separately store any records about the users of the system, and honest users can even remain anonymous to the content distributor. The main technical difficulty comes in designing tracing algorithms that can handle an exponentially large universe of possible identities, rather than just a polynomial set of indices $$i \in [N]$$i∈[N]. We solve this by abstracting out an interesting algorithmic problem that has surprising connections with seemingly unrelated areas in cryptography. We also extend our solution to a full "broadcast-trace-and-revoke" scheme in which the traced users can subsequently be revoked from the system. Depending on parameters, some of our schemes can be based only on the existence of public-key encryption while others rely on indistinguishability obfuscation.

To manage dynamic access control and deter pirate attacks on outsourced databases, a dynamic access control scheme with tracing is proposed. In our scheme, we introduce the traitor tracing idea into outsource databases, and employ a polynomial function and filter function as the basic means of constructing encryption and decryption procedures to reduce computation, communication, and storage overheads. Compared to previous access control schemes for outsourced databases, our scheme can not only protect sensitive data from leaking and perform scalable encryption at the server side without shipping the outsourced data back to the data owner when group membership is changed, but also provide trace-and-revoke features. When malicious users clone and sell their decryption keys for profit, our scheme can trace the decryption keys to the malicious users and revoke them. Furthermore, our scheme avoids massive message exchanges for establishing the decryption key between the data owner and the user. Compared to previously proposed publickey traitor tracing schemes, our scheme can simultaneously achieve full collusion resistance, full recoverability, full revocation, and black-box traceability. The proof of security and analysis of performance show that our scheme is secure and efficient.

Pairing-based public key systems have recently received much attention because bilinear property contributes to the designs of many cryptographic schemes. In 2002, Mitsunari et al. proposed the first pairing-based traitor tracing scheme with constant-size ciphertexts and private keys. However, their scheme has been shown to be insecure for providing traitor tracing functionality. Recently, many researches still try to propose efficient pairing-based traitor tracing schemes in terms of ciphertext and private key sizes. In this paper, we present a security claim for the design of pairing-based traitor tracing schemes. For a pairing-based traitor tracing scheme with constant-size ciphertexts and private keys, if the decryption key is obtained by some pairing operations in pairing-based public key systems, the scheme will suffer from a linear attack and cannot provide the traitor tracing functionality. Finally, we apply our security claim to attack a pairing-based traitor tracing scheme proposed by Yang et al. to demonstrate our result. Our security claim can offer a notice and direction for designing pairing-based traitor tracing schemes. Copyright © 2012 John Wiley & Sons, Ltd.

Traitor Tracing schemes are broadcast encryption systems where at least one of the traitors who were implicated in the construction of a pirate decoder can be traced. This traceability is required in various contents delivery system like satellite broadcast, DMB, pay-TV, DVD and so on. In this paper, we propose a public key traitor tracing scheme with key-update method. If the system manager can update a secret key which is stored in an authorized decode, it makes a pirate decoder useless by updating a secret key A pirate decoder which cannot update a secret key does not decrypt contents in next session or during tracing a traitor, this scheme has merits which will make a pirate decoder useless, therefore this scheme raises the security to a higher level.

Broadcast encryption provides a convenient method to distribute digital content to subscribers over an insecure broadcast channel so that only the qualified users can recover the data. Currently, there are only two broadcast encryption schemes designed for users with different privileges. In these schemes, users with higher privileges can decrypt more contents than those with low privileges, which is quite suitable for applications with different service levels. However, both schemes do not provide traitor tracing strategy. In this paper, we present a traitor tracing and revoking system for different privileges against pirate rebroadcast. We improve the tree structure and the media key block proposed by Jin and Lotspiech to suitable for applications with dynamic services, and then combine them with dynamic traitor tracing and revoking method by Kiayias and Pehlivanoglu. Dynamic services mean the users can change their privileges dynamically and the broadcast center can upgrade to hold more/less privileges when needed for marketing, while in both previous schemes the numbers of privileges are determined when the systems are setup and users' privileges are static. Our scheme uses subset cover method to trace and revoke users so that it can trace unlimited numbers of traitors and revoke unlimited numbers of users.

In this paper, a media content encryption/decryption algorithm is designed based on a chaos system and neural networks, which generates random sequences with chaos, and encrypts or decrypts media contents with neural networks in a parallel way. In this scheme, different decryption keys can be used to recover the media content into different copies. That is, the decryption operation gets the content containing certain random sequence that can be used as the identification. With respect to this property, the scheme is used for secure content distribution. Taking the audio content for example, it is encrypted by a key at the sender side and decrypted by different keys at the receiver side. The differences between decryption keys lead to different decrypted audio copies. If one customer distributes his copy to other unauthorized customers, the chaotic sequence contained in the copy can tell the illegal customer. The performances, including security, imperceptibility and robustness, are analyzed, and some experimental results are given to show the scheme's practicability.

Our goal is to design encryption schemes for mass distribution of data , which enable to (1) deter users from leaking their personal keys, (2) trace the identities of users whose keys were used to construct illegal decryption devices, and (3) revoke these keys as to render the devices dysfunctional. We start by designing an efficient revocation scheme, based on secret sharing. It can remove up to t parties, is secure against coalitions of up to t users, and is more efficient than previous schemes with the same properties. We then show how to enhance the revocation scheme with traitor tracing and self-enforcement properties. More precisely, how to construct schemes such that (1) each user’s personal key contains some sensitive information of that user (e.g., the user’s credit card number), in order to make users reluctant to disclose their keys. (2) An illegal decryption device discloses the identity of users that contributed keys to construct the device. And, (3) it is possible to revoke the keys of corrupt users. For the last point, it is important to be able to do so without publicly disclosing the sensitive information.

This paper provides a review on traitor tracing schemes that are developed to counter piracy strategies. The review starts with a formal definition of the traitor tracing schemes. The paper is then outlined based on two main strategies which may taken by digital content pirates. Mostly the pirates have strategy to make use leaked decryption key or leaked decrypted content. For each piracy strategy, we presents traitor tracing schemes that can be used to counter the piracy. We also analysis strength and weakness of each group of the schemes. At the end of this paper, we propose to combine some schemes for better protection.

In this paper we introduce an architecture for a multi-key pirate decoder which employs decryption keys from multiple traitors. The decoder has built-in monitoring and self protection functionalities and is capable of defeating most multiple-round based traitor tracing schemes such as the schemes based on the black-box confirmation method. In particular, the proposed pirate decoder is customized to defeat the private key and the public key fully collusion resistant traitor tracing (FTT) schemes, respectively. We show how the decoder prolongs a trace process so that the tracer has to give up his effort. FTT schemes are designed to identify all the traitors. We show that decoder enables the FTT schemes to identify at most 1 traitors. Finally, assuming the decoder is embedded with several bytes of memory, we demonstrate how the decoder is able to frame innocent users at will.

The development explained in this article proves that is possible to trace dishonest users who upload videos with sensitive content to the YouTube service. To achieve tracing these traitor users, fingerprint marks are embedded by a watermarking algorithm into each copy of the video before distributing it. Our experiments show that if the watermarking algorithm is carefully configured and the fingerprints are correctly chosen, the traitor, or a member of a set of traitors who have performed a collusion attack, can be found from a pirate video uploaded to the YouTube service.