Anonymous Communication Systems Research Articles

ДОСЛІДЖЕННЯ МОДЕЛЕЙ АНОНІМНОЇ МАРШРУТИЗАЦІЇ

Numerous solutions have been created for online anonymous communication. We do evaluations of security on several systems. We examine features such as Onion Routing, anonymous VPN services, probabilistic anonymity, and deterministic anonymity among different systems. There are also additional forms of anonymous communication that are discussed, including messaging, peer-to-peer communication, using the web, emailing, and using other Internet apps. We then go on to show several attack methods that aim to identify people who communicate anonymously. The objective of the research is to achieve an exact adjust between guaranteeing the adequacy and dependability of message delivery and ensuring customer anonymity. The NIAR model's non-interactive highlight makes it more valuable since it licenses secure communication without requiring nonstop client support. Communication privacy is threatened by an ever-growing volume of data generated by an ever-growing number of networked devices. Because of this, Anonymous Communication Systems (ACSs)—which offer the privacy qualities of anonymity, unsinkability, and observability—are recommended to conceal the relationship between transmitted communications and their senders and recipients. The objective of this essay is to evaluate the literature on Dining Cryptographers Networks (DCNs) in the subject of ACSs. Since the DCN-based techniques offer unconditional guarantees of observability, they are information-theoretically safe. Their computation and communication expense was considered high at the time, and scalability issues arose, which originally impeded their use for anonymous communications. By satisfying these targets, the research improves the state of encrypted communication systems and opens the door to a day when protecting client security will be a best need without sacrificing message delivery's significant dependability and efficiency.

Enhancing the Unlinkability of Circuit-Based Anonymous Communications with k-Funnels

Anonymous communication systems are essential tools for preserving privacy and freedom of expression. However, traffic analysis attacks make it challenging to maintain unlinkability in circuit-based anonymity networks like Tor, enabling adversaries to deanonymize communications. To address this problem, we introduce k-funnel, a new security primitive that enhances the unlinkability of circuit-based anonymity networks, and we present BriK, a Tor pluggable transport that implements k-funnels. k-Funnels offer k-anonymity to a group of k clients by jointly tunneling their circuits' traffic through a bridge while ensuring that the client-generated flows are indistinguishable. BriK incorporates several defense mechanisms against traffic analysis attacks, including traffic shaping schemes, synchronization protocols, and approaches for monitoring exposure to statistical disclosure attacks. Our evaluation shows that BriK is able to support web browsing and video streaming while offering k-anonymity. We evaluate the security of BriK against traffic correlation attacks leveraging state-of-the-art deep learning classifiers without considering auxiliary information and find it highly resistant. Although k-funnels require the cooperation of mutually trusted clients, limiting their coordination, our work presents a new practical solution to strengthen unlinkability in circuit-based anonymity systems.

B-Tor: Anonymous communication system based on consortium blockchain

B-Tor: Anonymous communication system based on consortium blockchain

Research on Blockchain Anonymous Communication Based on Key Derivation

Abstract With the continuous development of the Internet and communication technologies, network communication provides convenience but also brings security problems such as exposure of users' personal privacy information and theft, private tampering, and forgery of false information. Modern cryptography technology is an important safeguard against message eavesdropping and tampering, while the rapidly developing anonymous communication technology in this century makes it difficult for attackers to infer user's personal information and communication relationships. In response to the potential threats of traditional centralized systems such as central nodes being vulnerable to attacks and data storage being tampered with, this paper proposes a blockchain anonymous communication algorithm KDAC based on key derivation, which takes advantage of the decentralization, data immutability, consensus mechanism and anonymity of blockchain and combines the ECC cryptographic derivation algorithm and anonymous communication technology to realize the key-at-a-time, one-address-at-a-time The key derivation scheme ensures the message integrity and tamper-evident while effectively hiding the identity information of both communication parties. In addition, this paper also optimizes the blockchain anonymous communication system with key derivation. Users only need the initial key of blockchain nodes to join the network for communication, and the information transmission is difficult to trace based on the blockchain network, which can effectively guarantee communication security and anonymity. The experimental results show that the efficiency of the derived key algorithm is roughly in the same order of magnitude as that of the 256-bit AES symmetric encryption algorithm, which can play a better role in practical applications. On the other hand, the derived key generated based on the algorithm has complete randomness in association verification, and it is impossible to reverse the initial parameters, which can well guarantee the anonymity of user identity.

A Survey on Anonymous Communication Systems With a Focus on Dining Cryptographers Networks

Traffic analysis attacks can counteract end-to-end encryption and use leaked communication metadata to reveal information about communicating parties. With an ever-increasing amount of traffic by an ever-increasing number of networked devices, communication privacy is undermined. Therefore, Anonymous Communication Systems (ACSs) are proposed to hide the relationship between transmitted messages and their senders and receivers, providing privacy properties known as anonymity, unlinkability, and unobservability. This article aims to review research in the ACSs field, focusing on Dining Cryptographers Networks (DCNs). The DCN-based methods are information-theoretically secure and thus provide unconditional unobservability guarantees. Their adoption for anonymous communications was initially hindered because their computational and communication overhead was deemed significant at that time, and scalability problems occurred. However, more recent contributions, such as the possibility to transmit messages of arbitrary length, efficient disruption handling and overhead improvements, have made the integration of modern DCN-based methods more realistic. In addition, the literature does not follow a common definition for privacy properties, making it hard to compare the approaches’ gains. Therefore, this survey contributes to introducing a harmonized terminology for ACS privacy properties, then presents an overview of the underlying principles of ACSs, in particular, DCN-based methods, and finally, investigates their alignment with the new harmonized privacy terminologies. Previous surveys did not cover the most recent research advances in the ACS area or focus on DCN-based methods. Our comprehensive investigation closes this gap by providing visual maps to highlight privacy properties and discussing the most promising ideas for making DCNs applicable in resource-constrained environments.

Guest Editorial: Selected papers from the 24th International Conference on Information Security and Cryptology (ICISC 2021)

This is our first IET Information Security special issue from the Internation Conference on Information Security and Cryptology, which was held from December 1 to December 3, Seoul, South Korea, 2021. The aim of ICISC 2021 was to provide an international forum for the latest results of research, development, and applications within the field of information security and cryptography. In ICISC 2021, we received 63 submissions and were able to accept 23 papers for the presentation at the conference. Among accepted and presented papers at ICISC 2021, we selected six papers with high review scores and recommended them for publication in the special issue of IET information Security (via at least 30% extension). It is worth noting that the review and the selection process were successfully conducted by programme committee (PC) members, including reviewers dispatched from IET Information Security, and each paper underwent a blind review by at least three PC members. The special issue contains six papers on topic areas, including lattice-based protocol constructions (Topic A), lattice-based analysis algorithms (Topic B), efficient quantum circuit constructions (Topic C), and analysis on symmetric-key primitives (Topic D). Paper 1 by P. Ren, X. Gu, and Z. Wang investigates how to construct a quantum-safe password-authenticated key exchange (PAKE) as a cryptographic primitive that can establish secure remote communications between a client and a server. They suggest a new PAKE protocol based on module lattices with a rigorous security proof in the random oracle model. Taking the flexibility of the module learning with errors problem, they elaborately select 3 parameter sets to meet different application scenarios. Specifically, they show that their recommended PAKE implementation achieves 177-bit post-quantum security with a generous margin to cope with later improvement in the cryptanalysis. Their performance results indicate that the MLWE-PAKE is quite practical: compared with the latest Yang-PAKE, their PAKE reduces the communication cost and the running time by 36.8% and 13.8%, respectively. Paper 2 by V. Farzaliyev, J. Willemson, and J. K. Kaasik investigates Mix-networks as a general tool for building anonymous communication systems. They focus on the application case of post-quantum electronic voting where the number of votes to be mixed may reach hundreds of thousands or even millions. They propose an improved architecture for lattice-based post-quantum mix-nets featuring more efficient zero-knowledge proofs while maintaining established security assumptions. Their implementation scales up to 100,000 votes, still leaving a lot of room for future optimisation. Paper 3 by K. Yamamura, Y. Wang, and E. Fujisaki investigates an enumeration algorithm that is used as a subroutine for the BKZ algorithm, which is one of the most practical reduction algorithms. It is a critical issue to reduce the computational complexity of the enumeration algorithm. First, they improve the mechanism, called Primal Projective Reordering (PPR) method, over the previous reordering method proposed by Wang in ACISP 2018. Next, they propose a Dual Projective Recording method in dual lattice, and also they propose a condition to decide whether the reordering method should be adapted or not. Finally, they propose an improved BKZ algorithm with the reordering methods and our proposed condition. Preliminary experimental results show that their proposed reordering methods can successfully reduce the number of enumeration algorithm search nodes compared to the predecessor, for example, PPR reduces around 9.6% on average in 30-dimensional random lattices, and DPR reduces around 32.8% on average in 45-dimensional random lattices. Paper 4 by J. Lee, S. Lee, Y. S. Lee, and D. Choi suggests an efficient quantum circuit design of a given cryptographic algorithm in terms of reducing T-depth for time complexity efficiency. They propose a novel technique for reducing T-depth (and T-count) when some quantum circuits located between two Toffoli gates are interchangeable with a controlled phase gate (CP gate). They apply their technique to five types of quantum adders, reducing T-depth by more than 33%. They also present new SHA-256 quantum circuits, which have a critical path with only three quantum adders, while the critical paths of quantum circuits in the previous works consist of seven or 10 quantum adders. According to their four version of SHA-256 quantum circuit, T-depth of the proposed SHA-256 quantum circuit with the Width (the number of qubits) 797 is 16,055, which is remarkably reduced by about 85%. Another proposed quantum circuit only requires 768 qubits, which is the smallest width, to the best of their knowledge. Finally, one other version is the most time-efficient circuit with an overall Toffoli depth (and T-depth) that is less than 5000. Paper 5 by Y. Lee, J. Kang, D. Chang, and S. Hong presents preimage attacks on a round-reduced variant of GIMLI-HASH, in which the message-absorbing phase used 5-round GIMLI and the squeezing phase used 9-round GIMLI. They call this variant as 5-9-round GIMLI-HASH. Their preimage attack on 5-9-round GIMLI-HASH requires 294.44 time complexity and 297 memory complexity. Also, this method can be reached up to round shifted 10-round GIMLI in the squeezing phase. Their first attack requires the memory for storing several precomputation tables in GIMLI SP-box operations. In their second attack, they take a time-memory trade-off approach, reducing memory requirements for precomputation tables but increasing computing time for solving SP-box equations by the SAT solver. This attack requires 266.17 memory complexity and 296+ε time complexity, where ε is the time complexity for solving SP-box equations. Their experiments using the CryptoMiniSat SAT solver show that the maximum time complexity for ε is about 220.57 9-round GIMLI. Paper 6 by S. Lim and D. G. Han examines a differential fault attack on the PIPO, a lightweight block cipher, which was proposed in ICISC 2020. The PIPO was designed for providing robust security strength while having less overhead when using the side-channel analysis countermeasure. A differential fault attack is a type of side-channel analysis that induces fault in cryptographic operations and utilises difference information that occurs. They proposed a single-bit flip-based differential fault attack on PIPO, where, through 64 fault ciphertexts, their proposed attack has a 98.9% probability of recovering the correct secret key of PIPO 64/128. They evaluated the proposed attack not only through simulations but also through electromagnetic fault injection. All of the papers selected for this Special Issue show that further improvements of information security and cryptography are made in the topic areas of post-quantum cryptography and security analysis on block ciphers. Especially, various experimental results by authors will clearly show the reader how advanced their results are, compared to the current research works related to six selected papers. In the meanwhile, there are still many challenges in this field that require future research attentions, such as efficient construction of lattice-based cryptographic primitives, analysis on lattice-based reduction algorithms, and more realistic quantum attacks against post-quantum cryptographic primitives and their underlying complexity assumptions. We hope to see more advanced research results on these topics in the near future. We appreciate all of the authors for their contributions to this Special Issue, 'Selected papers from the 24th International Conference on Information Security and Cryptology (ICISC 2021)'. We would also like to extend the appreciation to the anonymous reviewers who have provided insightful comments and suggestions in improving the quality of the manuscripts. Special thanks go to the Editors-in-Chief and the Deputy Editor of IET Information Security for giving us this great opportunity. Jong Hwan Park received the B.S. degree in the Department of Mathematics from Korea University, Seoul, Korea, in 1999, and the M.S. and Ph.D. degrees in the Graduate School of Information Security from Korea University, Seoul, Korea, in 2004 and 2008, respectively. From 2009 to 2011, he served as a research professor from Kyung Hee University, and from 2011 to 2013, he served as a research professor in Korea University. From 2013 to 2019, he served as an assistant professor in the Department of Computer Science, Sangmyung University, Seoul, Korea. Since 2020, he has served as an associate professor. His research areas include functional encryption, lattice-based cryptographic primitives, broadcast encryption, and various zero-knowledge-based cryptographic protocols.

Improved lattice‐based mix‐nets for electronic voting

Mix-networks were first proposed by Chaum in the late 1970s–early 1980s as a general tool for building anonymous communication systems. Classical mix-net implementations rely on standard public key primitives (e.g., ElGamal encryption) that will become vulnerable when a sufficiently powerful quantum computer will be built. Thus, there is a need to develop quantum-resistant mix-nets. This article focuses on the application case of electronic voting where the number of votes to be mixed may reach hundreds of thousands or even millions. We propose an improved architecture for lattice-based post-quantum mix-nets featuring more efficient zero-knowledge proofs while maintaining established security assumptions. Our current implementation scales up to 100,000 votes, still leaving a lot of room for future optimisation.

OrgAn: Organizational Anonymity with Low Latency

There is a growing demand for network-level anonymity for delegates at global organizations such as the UN and Red Cross. Numerous anonymous communication (AC) systems have been proposed over the last few decades to provide anonymity over the internet; however, they introduce high latency overhead, provide weaker anonymity guarantees, or are difficult to deploy at the organizational networks. Recently, the PriFi system introduced a client/relay/server model that suitably utilizes the organizational network topology and proposes a low-latency, strong-anonymity AC protocol. Using an efficient lattice-based (almost) keyhomomorphic pseudorandom function and Netwon’s power sums, we present a novel AC protocol OrgAn in this client/relay/server model that provides strong anonymity against a global adversary controlling the majority of the network. OrgAn’s cryptographic design allows it to overcome several major problems with any realistic PriFi instantiation: (a) unlike PriFi, OrgAn avoids frequent, interactive, slot-agreement protocol among the servers; (b) a PriFi relay has to receive frequent communication from the servers, which can not only become a latency bottleneck but also reveal the access pattern to the servers and increases the chance of server collusion/coercion, while OrgAn servers are absent from any real-time process. We demonstrate how to make this public-key cryptographic solution scale equally well as the symmetric-cryptographic PriFi with practical pre-computation and storage requirements. Through a prototype implementation, we show that OrgAn provides similar throughput and end-to-end latency guarantees as PriFi, while still discounting the setup challenges in PriFi.

A Traffic Splitting Algorithm for Load Balancing in Tor.

As the most popular anonymous communication system, Tor provides anonymous protection for users by sending their messages through a series of relays. Due to the use of the bandwidth-weighted path selection algorithm, many more users choose routers with high bandwidth as relays. This will cause the utilization of high bandwidth routers to be much higher than that of low bandwidth routers, which will bring congestion risk. The Quality of Service (QoS) is difficult to guarantee for users who need delay-sensitive services such as web browsing and instant messaging. To reduce the average load of routers and improve the network throughput, we propose a circuit construction method with multiple parallel middle relays and conduct a dynamic load allocation method. The experiment demonstrates that our proposed method can provide better load balancing. Compared with other multipath anonymous communication networks, our proposed method can provide better anonymity.

SAD: Website Fingerprinting Defense Based on Adversarial Examples

Website fingerprinting (WF) attacks can infer website names from encrypted network traffic when the victim is browsing the website. Inherent defenses of anonymous communication systems such as The Onion Router(Tor) cannot compete with current WF attacks. The state-of-the-art attack based on deep learning can gain over 98% accuracy in Tor. Most of the defenses have excellent defensive capabilities, but it will bring a relatively high bandwidth overhead, which will seriously affect the user’s network experience. And some defense methods have less impact on the latest website fingerprinting attacks. Defense-based adversarial examples have excellent defense capabilities and low bandwidth overhead, but they need to get the complete website traffic to generate defense data, which is obviously impractical. In this article, based on adversarial examples, we propose segmented adversary defense (SAD) for deep learning-based WF attacks. In SAD, sequence data are divided into multiple segments to ensure that SAD is feasible in real scenarios. Then, the adversarial examples for each segment of data can be generated by SAD. Finally, dummy packets are inserted after each segment original data. We also found that setting different head rates, that is, end points for the segments, will get better results. Experimentally, our results show that SAD can effectively reduce the accuracy of WF attacks. The technique drops the accuracy of the state-of-the-art attack hardened from 96% to 3% while incurring only 40% bandwidth overhead. Compared with the existing proposed defense named Deep Fingerprinting Defender (DFD), the defense effect of SAD is better under the same bandwidth overhead.

Edge-Based Detection and Classification of Malicious Contents in Tor Darknet Using Machine Learning

With the increase of data in the network, the load of servers and communication links becomes heavier and heavier. Edge computing can alleviate this problem. Due to a sea of malicious contents in Darknet, it is of high research value to combine edge computing with content detection and analysis. Therefore, this paper illustrates an intelligent classification system based on machine learning and Scrapy that can detect and judge fleetly categories of services with malicious contents. Because of the nondisclosure and short survival time of Tor Darknet domain names, obtaining uniform resource locators (URLs) and resources of the network is challenging. In this paper, we focus on a network based on the Onion Router (tor) anonymous communication system. We designed a crawler program to obtain the contents of the Tor network and label them into six classes. We also construct a dataset which contains URLs, categories, and keywords. Edge computing is used to judge the category of websites. The accuracy of the classifier based on a machine learning algorithm is as high as 89%. The classifier will be used in an operational system which can help researchers quickly obtain malicious contents and categorize hidden services.

UDM: Private user discovery with minimal information disclosure

We present and analyze User Discovery with Minimal information disclosure (UDM), a new protocol for user discovery in anonymous communication systems that minimizes the information disclosed to the system and users. UDM solves the following user-discovery problem. User Alice wishes to communicate with Bob over an anonymous communication system, such as cMix or Tor. Initially, each party knows each other’s public contact identifier (e.g., email address or phone number), but neither knows the other’s private platform identifier in the communication system. If both parties wish to communicate with each other, UDM enables them to establish a shared secret and learn each other’s private platform identifier. Unlike existing systems, including those based on private set intersection, UDM learns nothing about the social contacts of the users, is not vulnerable to off-line dictionary attacks that expose contact lists, does not reveal platform identifiers to users without the owner’s explicit permission, and enjoys low computation and communication complexity. Using the anonymous communication system, each pair of users who wish to communicate with each other uploads to the user-discovery system their private platform identifier, encrypted with a key derived from their shared secret. Indexing their request by a cryptographic tag derived from their shared secret, each user can then download each other’s encrypted private platform identifier. In doing so, UDM uses an untrusted user-discovery system, which processes and stores only public information or values encrypted with keys it does not know. Therefore, from the data values it processes, UDM cannot learn any information about the social contacts of its users.

Survey of anonymous communication system

Survey of anonymous communication system

TOR Anonymous Traffic Fingerprint Extraction and Recognition Based on Neural Network

The TOR anonymous communication system is an important means to protect network communication security and user privacy, but there are still criminals trying to destroy the confidentiality of the anonymous communication system through some special methods. Aiming at the abuse of the TOR anonymous communication system, this paper proposes a neural network-based anonymous traffic identification method, which uses a one-dimensional convolutional neural network for feature extraction, prediction and classification, and finally integration. In the experiment, nearly 100 websites were selected for the flow feature extraction and recognition based on one-dimensional convolutional neural network. The recognition accuracy rate is 87.5%, indicating that this method can effectively fingerprint TOR anonymous communication.

RACOON++: A Semi-Automatic Framework for the Selfishness-Aware Design of Cooperative Systems

A challenge in designing cooperative distributed systems is to develop feasible and cost-effective mechanisms to foster cooperation among selfish nodes, i.e., nodes that strategically deviate from the intended specification to increase their individual utility. Finding a satisfactory solution to this challenge may be complicated by the intrinsic characteristics of each system, as well as by the particular objectives set by the system designer. Our previous work addressed this challenge by proposing RACOON, a general and semi-automatic framework for designing selfishness-resilient cooperative systems. RACOON relies on classical game theory and a custom built simulator to predict the impact of a fixed set of selfish behaviours on the designer's objectives. In this paper, we present RACOON++, which extends the previous framework with a declarative model for defining the utility function and the static behaviour of selfish nodes, along with a new model for reasoning on the dynamic interactions of nodes, based on evolutionary game theory. We illustrate the benefits of using RACOON++ by designing three cooperative systems: a peer-to-peer live streaming system, a load balancing protocol, and an anonymous communication system. Extensive experimental results using the state-of-the-art PeerSim simulator verify that the systems designed using RACOON++ achieve both selfishness-resilience and high performance.

MSFA: Multiple System Fingerprint Attack Scheme for IoT Anonymous Communication

For the past few years, Internet of Things (IoT) has developed rapidly and been extensively used. However, its transmission security and privacy protection are insufficient, which limits the development of IoT to a certain extent. As a technology of IoT information transmission, anonymous communication technology comes into being as an important means to ensure the security of healthcare data, which can better protect users’ privacy in some ways. Nowadays, a variety of attack techniques for anonymous communication systems have been proposed by the academic community to track senders and receivers or discover communications between two users. Thus, the MSFA (Multiple System Fingerprint Attack) scheme for anonymous communication systems is presented in this paper where the MSFA scheme architecture, implementation in the Tor environment, and experimental data processing are described. Through a comparative analysis between two traces of visiting the same website based on the edit distance, it is shown that the longer the length of the site traffic data, the greater the edit distance of the site access traffic and the larger the range.

A Survey on Measuring Anonymity in Anonymous Communication Systems

The popularity of Internet applications has made communication privacy an increasingly important security requirement. As an important aspect of privacy, anonymity ensures that a subject may use resources or services without disclosing user identity or corresponding relationships. Since the seminal work by Chaum for anonymous communication, many different anonymous communication systems, and anonymous protocols have been developed and investigated extensively. In recent years, anonymous communication systems have evolved from academic tools used by specialists to mass-market software used by millions of ordinary people. How to evaluate and quantify the anonymity that different anonymous communication systems can offer has been a new focus. Though some efforts have been made on anonymity metrics and measuring techniques, systematic research on measuring anonymity of anonymous communication systems is still needed. In this paper, we give a comprehensive overview of state-of-the-art research on measuring anonymity. We first summarize the anonymous mechanisms applied by different anonymous systems. We then introduce the formalization of the notion of anonymity for measuring the anonymity degree. Further, metrics based on various theories and approaches are reviewed. We particularly elaborate on the metrics based on information theory as a separate section because of its popularity and multiple branches. The metrics based on information entropy is probably of the greatest interest.

ObliComm: Towards Building an Efficient Oblivious Communication System

Anonymous Communication (AC) hides traffic patterns and protects message metadata from being leaked during message transmission. Many practical AC systems have been proposed aiming to reduce communication latency and support a large number of users. However, how to design AC systems which possess strong security property and at the same time achieve optimal performance (i.e., the lowest latency or highest horizontal scalability) has been a challenging problem. In this paper, we propose an ObliComm framework, which consists of six modular AC subroutines. We also present a strong security definition for AC, named oblivious communication, encompassing confidentiality, unobservability, and a new requirement sending-and-receiving operation hiding. The AC subroutines in ObliComm allow for modular construction of oblivious communication systems in different network topologies. All constructed systems satisfy oblivious communication definition and can be provably secure in the universal composability (UC) framework. Additionally, we model the relationship between the network topology and communication measurements by queuing theory, which enables the system’s efficiency can be optimized and estimated by quantitative analysis and calculation. Through theoretical analyses and empirical experiments, we demonstrate the efficiency of our scheme and soundness of the queuing model.

An Intrusion Tracking Watermarking Scheme

With the rapid development of edge computing technology, the scale of the network continues to expand. Various types of applications are becoming more widespread. In the edge computing, existing network agents, NAT, IP tunneling technologies, and rapidly evolving anonymous communication systems provide convenience for attackers to hide real IP. In addition, the attacker forms a “stepping” chain by breaking through several intermediate systems of the edge computing network. Thereby implementing an invisible intrusion attack across multiple autonomous domains can increase the difficulty of intrusion tracking. Aiming at the problem of insufficient applicability of existing interval centroid based watermarking technique, this paper proposes a histogram specified interval centroid-based watermarking technique. It improves cross-domain collaborative intrusion tracking. This technique improves the resistance of the prior art to multi-flow attacks in edge computing. It decreases the time and space overhead of the detector. Compared with other interval centroid based watermarking techniques, this method has stronger concealment. The proposed method can effectively defend against multi-flow attacks of edge computing. The time and space overhead of the detector can be reduced when multiple attack flows are tracked in parallel. Thus, it is suitable for edge computing. The robustness and adaptability are improved by this method.

Anonymous Communication via Anonymous Identity-Based Encryption and Its Application in IoT

Under the environment of the big data, the correlation between the data makes people have a greater demand for privacy. Moreover, the world has become more diversified and democratic than ever before. Freedom of speech is considered to be very important; thus, anonymity is also a very important security demand. The research of our paper proposes a scheme which can ensure both the privacy and the anonymity of a communication system, that is, the protection of message privacy while ensuring the users’ anonymity. It is based on anonymous identity-based encryption (IBE), by which the users’ metadata are protected. We implement our scheme in JAVA with Java pairing-based cryptography library (JPBC); the experiment shows that our scheme has significant advantage in efficiency compared with other anonymous communication system. Internet-of-Things (IoT) involves many devices, and privacy of devices is very significant. Anonymous communication system provides a secure environment without leaking metadata, which has many application scenarios in IoT.