Misbehaving Users Research Articles

S-Cred: An accountable anonymous credential scheme with decentralized verification and flexible revocation

The popularization of digital credentials brings convenience to people, but it also increases the risks of privacy leakage and capability abuse. Designing an accountable anonymous credential scheme offers a promising solution to this problem. However, most existing schemes of accountable anonymous credentials cannot effectively support both decentralized verification and flexible revocation. In this paper, we present S-Cred, an accountable anonymous credential scheme with decentralized verification and flexible revocation, to provide a delegation issuance method for credentials. The ownership of attributes will be transferred to users' temporary identities on the blockchain. In order to prevent credentials misuse, we also design several constraint mechanisms for tracing misbehaving users and revoking their credentials. We further construct a non-fungible obfuscation mechanism by introducing special roles called cloakers. In addition, this paper conducts analysis on security, functionality, efficiency and performance. The results show that S-Cred combines decentralized authentication and flexible revocation with a low computational cost in verification, which demonstrates the practicality of our solution.

Generic Construction of Black-Box Traceable Attribute-Based Encryption

Attribute-based encryption (ABE) has been widely used to provide fine-grained access control to encrypted data in cloud computing. However, in practice, since the attributes are shared by multiple users in the ABE system, it is difficult to identify malicious users which intentionally but implicitly reveal their own ABE secret keys for some purpose. In recent years, a substantial amount of work focused on designing efficient tracing mechanisms to identify such misbehaving users on ABE. In this paper, we propose an efficient generic construction of black-box traceable ABE to identify the traitors. Our construction supports (public) adaptive black-box traceability and has short keys and short ciphertexts that are independent of the number of users. Technically, our construction relies on a generic transformation from any attribute-based inner-product functional encryption (ABIPFE) scheme to black-box traceable ABE system. Furthermore, to instantiate our generic construction from standard lattices, we propose the first lattice-based ABIPFE scheme, which is proven weakly selective secure in the standard model.

Revocable Certificateless Public Key Encryption With Outsourced Semi-Trusted Cloud Revocation Agent

Certificateless public key cryptography (CL-PKC) not only eliminates the need for certificates in traditional certificate-based PKC but also solves the inherent key escrow problem in identity-based PKC. However, an unsolved but critical issue in CL-PKC is how to revoke a misbehaving user. Some revocable certificateless public key encryption (RCL-PKE) schemes have been proposed, but these schemes have two main drawbacks: 1) public key uniqueness is not guaranteed, thus allowing the existence of multiple copies of each initial secret key. 2) The existing outsourced RCL-PKE schemes place excessive trust in the cloud server, which may continue to update decryption keys stealthily for misbehaving users. In this paper, we address these issues by proposing a novel RCL-PKE with semi-trusted cloud revocation agents (s-CRAs). We describe the framework and the security model for the RCL-PKE with s-CRA and prove that the proposed scheme is semantically secure against adaptive chosen-ciphertext attacks under the bilinear Diffie-Hellman assumption in the random oracle model. Furthermore, we compare the proposed scheme with previous RCL-PKE schemes in terms of performance and robustness. The evaluation results show that the proposed scheme achieves public key uniqueness and reliable revocation flexibility at low computational and communication costs.

User interactions and behaviors in a large-scale online emotional support service

Among the most important reasons why people communicate with each other is to share and support each other through emotional problems, yet most online social systems are uncomfortable or unsafe spaces for this purpose. This has led to the development of online emotional support systems, where users needing to speak to someone can anonymously connect to a crowd of trained listeners for a one-on-one conversation. Toward understanding the qualities of this emerging type of online social system, this article examines the users, conversations, and activities performed across 7 Cups, a massive, vibrant emotional support system with a community of listeners ready to help those with any number of emotional issues. The study makes intriguing insights along the worldwide adoption of the service, the need of its users to seek support from many others, a power-law effect of listener popularity, that users have a penchant to connecting to others along common interests and that a core periphery-like structure emerges among conversation networks, and identifies qualities of the system that drive user engagement and retention. We further study the words and actions of misbehaving users who have been reported on or blocked, and build a machine learning classifier able to anticipate their undesirable actions with reasonable accuracy and very low false positive rate. The qualities recovered gave insight into the user dynamics and communication structure of an online emotional support service, the features that drive engagement, and a means of identifying misbehaving users automatically.

Trust management in cognitive radio networks: A survey

SummaryCognitive radio is proposed to solve the interference and underutilized license problems. With the development of the cognitive functionalities, classical and new security threats become challenging. To make wireless cognitive radio networks more secure and more reliable, several approaches have been proposed in the literature. In recent years, trust and reputation management (TRM) techniques are more and more considered for cognitive radio networks to secure them against the malicious and misbehaving users that try to deprive others from using the white space. The scope of this survey is to give a comprehensive overview about the existing TRM‐based mechanisms proposed for the cognitive radio networks. We expose the existing classifications of TRM techniques, then we introduce a new classification that takes into account, more exhaustively, different TRM properties and approaches.

Privacy-Preserving Cooperative Route Planning

Today's street traffic is still largely inefficient. Overburdened roads lead to congestions, accidents, and unnecessary pollution. The increasing interconnection of traffic participants into the Internet of Vehicles (IoV) has tremendous potential for improving this issue. Cooperative route planning, e.g., is a concept for optimizing vehicular routing on a global scale by gathering data about planned routes from interconnected vehicles. As in other IoV applications, the benefits of such a system come at the cost of an increased privacy risk for participating users. Published routes include both the current and the planned future locations of drivers and passengers-all highly sensitive pieces of information. In the scope of this paper, we demonstrate how cooperative route planning can be realized with strong privacy guarantees without significant cuts in utility or cost. According to our knowledge, this is the first work to consider in this issue. We propose a scheme by which vehicles can publish their intent to pass at specific waypoints at approximate times in an anonymous fashion. While providing complete unlinkability of published intentions to individual users, our scheme is protected against abuse, with misbehaving (i.e., lying) users quickly losing their right to participate.

TEAP: trust‐enhanced anonymous on‐demand routing protocol for mobile ad hoc networks

Security plays a major role in implementing mobile ad hoc networks (MANET) for communication in an adverse environment. This study introduces the concept of anonymity for an informant who identifies and reports anonymously the misbehaviour of the users in the network. The trust-enhanced anonymous on-demand routing protocol (TEAP) is proposed to restrain the misuse of anonymity in two methods. In the first method, a user is revealed as a misbehaving user to other users, if it does not send any cooperative message, upon receiving two warnings. In the second method, if a user attempts to send multiple claims against a particular user for the same reason it will also be termed as a misbehaving user. The TEAP protocol is designed based upon broadcast with trapdoor information is a cryptography concept which is used to detect the misbehaving users anonymously in the network. The simulation results prove the necessity of anonymity in MANET and the effectiveness of this protocol in achieving such anonymity.

Extended Nymble: Method for Tracking Misbehaving Users Anonymosly While Blocking

We have many of anonymizing networks which provide users to access services of server anonymously. Anonymity has received increasing attention in the literature due to user awareness of their privacy. Nowadays, anonymity provides protection to users to enjoy network services without being traced. Anonymizing networks such as Tor allow users to access Internet services privately by using a series of routers to hide the client's IP address from the server. Web site administrators routinely rely on IPaddress blocking for disabling access to misbehaving users, but blocking IP addresses is not practical if the abuser routes through an anonymizing network. As a result, administrators block all known exit nodes of anonymizing networks, denying anonymous access to misbehaving and behaving users alike. To address this problem Nymble is developed, a system in which servers can misbehaving users. We present extensions to nymble framework for anonymizing blacklisting schemes. First, we provide a mechanism to nymble manager to track blacklisting of user in multiple linking windows while preserving anonymity of the users. Some users always look to misbehave with servers; there major intention is to make the server down. The problem with nymble is nymble manager blacklist a user for one likability window (i.e. 1 day), on the other day again he can misbehave with same server or other server. He can continue it as his everyday activity as Nymble manager doesn't have any mechanism to identify such type of users while preserving anonymity. To address this problem, we present a method which can identify such users, while preserving anonymity and nymble manager with identified information can decide upon how much time to blacklist a misbehaving user. We also suggest some algorithms which are changed in comparison to existing nymble.

Blactr: A Technique to Revoke the Misbehaving Users with TTP

Anonymous credential systems permit the users to authenticate themselves in a privacy- preserving way. An anonymous credential system is of major practical relevance because it is the best means of providing privacy for users. In this paper, we propose a technique known as Blacklistable Anonymous Credentials with Trust Reputation (BLACTR) for revoking misbehaving users with Trusted Third Party (TTP). The technique uses both Certifying Authority (CA) review as well as other user reviews in order to blacklist a user making use of the fuzzy and rule matched to check if the person is to be blacklisted or not. The proposed technique performed well when compared to BLAC and BLACR.

Open IPTV 환경에서 재암호화 과정 없는 댁내 컨텐츠 분배를 위한 키관리 기법

Due to the advancement of IPTV technologies, open IPTV services are a step closer to becoming reality. In such service environment, users are able to enjoy IPTV services using a variety of devices available at their home domain. However, it is impossible to get such flexible services at their convenience unless each of devices is individually connected to Set-Top-Box (STB) because of Conditional Access System (CAS) or service providers otherwise allow STB to freely distribute decoded contents to every user devices attached to STB. In this paper, we propose a key management scheme for securely distributing contents from STB to multiple user devices at home domain. The proposed scheme also makes the service providers be able to control the access rights to each of user devices without installing individual STBs. It is achieved by computationally dividing a private key of RSA signature scheme into three parts and thus makes possible to distribute the contents scrambled through a underlying CAS mechanism without re-encrypting them that the existing scheme should employ. It improves significantly computation and communication complexities, maintaining it as secure as the existing schemes. Additionally, it prevents misbehaving users from illegally distributing the contents from STB to their devices available at home domain.

PEREA

Several anonymous authentication schemes allow servers to revoke a misbehaving user's ability to make future accesses. Traditionally, these schemes have relied on powerful Trusted Third Parties (TTPs) capable of deanonymizing (or linking) users' connections. Such TTPs are undesirable because users' anonymity is not guaranteed, and users must trust them to judge misbehaviors fairly. Recent schemes such as Blacklistable Anonymous Credentials (BLAC) and Enhanced Privacy ID (EPID) support “privacy-enhanced revocation”— servers can revoke misbehaving users without a TTP's involvement, and without learning the revoked users' identities. In BLAC and EPID, however, the computation required for authentication at the server is linear in the size (L) of the revocation list , which is impractical as the size approaches thousands of entries. We propose PEREA, a new anonymous authentication scheme for which this bottleneck computation is independent of the size of the revocation list . Instead, the time complexity of authentication is linear in the size of a revocation window K ≪ L , the number of subsequent authentications before which a user's misbehavior must be recognized if the user is to be revoked. We extend PEREA to support more complex revocation policies that take the severity of misbehaviors into account. Users can authenticate anonymously if their naughtiness , i.e., the sum of the severities of their blacklisted misbehaviors, is below a certain naughtiness threshold. We call our extension PEREA-Naughtiness. We prove the security of our constructions, and validate their efficiency as compared to BLAC analytically and quantitatively.