Anonymous System Research Articles

Anonymization Framework for Securing Protected Health Information in a Complex Dataset of Medical Narratives

It is imperative in a medical domain that protection of information does not allow an individual to be overlooked. In medical domain, research community encourages use of real-time datasets for research purposes. These real-time datasets contain structured and unstructured (natural language free text) information that can be useful to researchers in various disciplines including computational linguistics. On the other hand, these real-time datasets cannot be distributed without anonymization of Protected Health Information (PHI). The information of PHI (such as Name, age, address, etc.) that can identify an individual is unethical. Therefore, we present a rule-based Natural Language Processing (NLP) anonymization system using a challenging corpus containing medical narratives and ICD-10 codes (medical codes). This anonymization module can be used for pre-processing the corpus containing identifiable information. The corpus used in this research contains '2534' PHIs in '1984' medical records in total. 15% of the labelled corpus was used for improvement of guidelines in the identification and classification of PHI groups and 85% was held for the evaluation. Our anonymization system follows two step process: (1) Identification and cataloging PHIs with four PHI categories ('Patients Name', 'Doctors Name', 'Other Name [Names other than patients and doctors]', 'Place Name'), (2) Anonymization of PHIs by replacing identified PHIs with their respective PHI categories. Our method uses basic language processing, dictionaries, rules and heuristics to identify, classify and anonymize PHIs with PHI categories. We use standard metrics for evaluation and our system outperforms against human annotated gold standard with 100% of F-measure by increasing 39% from baseline results, which proves the reliability of data usage for research.

A Signature Scheme with Unlinkable-yet-Accountable Pseudonymity for Privacy-Preserving Crowdsensing

Crowdsensing requires scalable privacy-preserving authentication that allows users to send anonymously sensing reports, while enabling eventual anonymity revocation in case of user misbehavior. Previous research efforts already provide efficient mechanisms that enable conditional privacy through pseudonym systems, either based on Public Key Infrastructure (PKI) or Group Signature (GS) schemes. However, previous schemes do not enable users to self-generate an unlimited number of pseudonyms per user to enable users to participate in diverse sensing tasks simultaneously, while preventing the users from participating in the same task under different pseudonyms, which is referred to as sybil attack. This paper addresses this issue by providing a scalable privacy-preserving authentication solution for crowdsensing, based on a novel pseudonym-based signature scheme that enables unlinkable-yet-accountable pseudonymity. The paper provides a detailed description of the proposed scheme, the security analysis, the performance evaluation, and details of how it is implemented and integrated into a real crowdsensing platform.

Use of a Mobile Anonymous Question-Raising System to Assist Flipped-Classroom Learning

Flipped classroom emphasizes the following. First, the instructor uses a digital platform to store course contents, including video lectures. Then, students retrieve these contents from the platform and learn by themselves before class. Finally, the instructor helps the students acquire their knowledge by asking questions in class, thereby helping the students to attain their learning goals. In previous studies, it was found that students might be affected by their peers and their own personalities, causing them not to express their opinions and views; this in turn might cause the students not to learn well; in some extreme cases, some students might even give up entirely. To solve the problem that students may hesitate to ask questions in class, this research developed a mobile anonymous question-raising system (MAQ) and used it to help students raise questions. By conducting an educational experiment, it was found that the use of MAQ in class could indeed help students to learn better in a flipped classroom setting.

Mutual exclusion in fully anonymous shared memory systems

Process anonymity has been studied for a long time. Memory anonymity is more recent. In an anonymous memory system, there is no a priori agreement among the processes on the names of the shared registers. As an example, a shared register named A by a process p and a shared register named B by another process q may correspond to the very same register X, while the same name C may correspond to different register names for the processes p and q, and this remains unknown to the processes. This article introduces the full anonymous model, namely a model in which both the processes and the registers are anonymous. A fundamental question is then “is this model meaningful?”, which can be translated as “can non-trivial fundamental problems be solved in such a very weak computing model?”This article answers this question positively. More precisely, it presents a deadlock-free mutual exclusion algorithm in such a fully anonymous model where the anonymous registers are read/modify/write registers. This algorithm assumes that m (the number of shared registers) and n (the number of processes) are such that m is relatively prime with all the integers ℓ∈{1,...,n}. Combined with a previous result (PODC 2019) on mutual exclusion in memory anonymous (but not process anonymous) systems, it follows that this condition is both necessary and sufficient for the existence of such an algorithm in fully anonymous systems. As far as we know, this is the first time full anonymity is considered, and where a non-trivial concurrency-related problem is solved in such a very strong anonymity context.

Data Anonymization Using Pseudonym System to Preserve Data Privacy

Data collection and storage in a large size is done on a routine basis in any company or organization. To this end, wireless network infrastructure and cloud computing are two widely-used tools. With the use of such services, less time is needed to attain the required output, and also managing the jobs will be simpler for users. General services employ a unique identifier for the aim of storing data in a digital database. However, it may be associated with some limitations and challenges. There is a link between the unique identifier and the data holder, e.g., name, address, Identity card number, etc. Attackers can manipulate a unique identifier for stealing the whole data. To get the data needed, attackers may even eavesdrop or guess. It results in lack of data privacy protection. As a result, it is necessary to take into consideration the data privacy issues in any data digital data storage. With the use of current services, there is a high possibility of exposure and leak of data/information to an unauthorized party during their transfer process. In addition, attacks may take place against services; for instance spoofing attacks, forgery attacks, etc. in the course of information transaction. To address such risks, this paper suggests the use of a biometric authentication method by means of a palm vein during the authentication process. Furthermore, a pseudonym creation technique is adopted to make the database record anonymous, which can make sure the data is properly protected. This way, any unauthorized party cannot gain access to data/information. The proposed system can resolve the information leaked, the user true identity is never revealed to others.

Using Security Questions to Link Participants in Longitudinal Data Collection.

Anonymous data collection systems are often necessary when assessing sensitive behaviors but can pose challenges to researchers seeking to link participants over time. To assist researchers in anonymously linking participants, we outlined and tested a novel security question linking (security question linking; SEEK) method. The SEEK method includes four steps: (1) data management and standardization, (2) many-to-many matching, (3) fuzzy matching, and (4) rematching and verification. The method is demonstrated in SAS with two samples from a longitudinal study of adolescent dating violence. After an initial assessment during a laboratory visit, participants were asked to complete an online assessment either (a) once, 3months later (Sample 1, n = 60), or (b) three times at 1-month intervals (Sample 2, n = 140). Demographics, eye color, and responses to nine security questions were used as key variables to link responses from the laboratory and online follow-up assessments. The rates of matched cases were 100% in Sample 1 and from 94.3 to 98.3% in Sample 2. To quantify the confidence in the data quality of successfully matched pairs, we reported the means and standard deviations of the number of matched security questions. In addition, we reported the rank order and counts of the mismatched components in key variables. Results indicate that the SEEK method provides a feasible and reliable solution to link responses in longitudinal studies with sensitive questions.

A practical solution to clone problem in anonymous information system

Cloning user's identity is always a thorny problem for an information system, especially for an anonymous system. With the development of big data applications, clone behaviors sometimes even become attacks on these systems. But until now, there has been no very satisfactory anti-clone scheme in the anonymous system. After analyzing the problems in existing anti-clone schemes, without any assumptions about physical security, we provide a practical solution to the clone problem in anonymous authentication system. In our scheme, the authentication is not only related to user's private key, but also related to user's current state, which is constantly updated by the system. Therefore, the authentication trajectories of user and clone will inevitably overlap, and it results in information leakage so as to indentify clone behaviors and revoke clone user's credential. Meanwhile, we prove that honest users are truly anonymous and their login behaviors are unlinkable with complete security proofs. According to the analysis of the system function and the system efficiency, our scheme is much more efficient and has the best anti-clone properties comparing with the existing schemes.

An Efficient Blacklistable Anonymous Credentials without TTP of Tracing Authority Using Pairing-Based Accumulator

In conventional ID-based user authentications, privacy issues may occur, since users’ behavior histories are collected in Service Providers (SPs). Although anonymous authentications such as group signatures have been proposed, these schemes rely on a Trusted Third Party (TTP) capable of tracing misbehaving users. Thus, the privacy is not high, because the TTP of tracing authority can always trace users. Therefore, the anonymous credential system using a blacklist without the TTP of tracing authority has been proposed, where blacklisted anonymous users can be blocked. Recently, an RSA-based blacklistable anonymous credential system with efficiency improvement has been proposed. However, this system still has an efficiency problem: The data size in the authentication is O(K0), where K0 is the maximum number of sessions in which the user can conduct. Furthermore, the O(K0)-size data causes the user the computational cost of O(K0) exponentiations. In this paper, a blacklistable anonymous credential system using a pairing-based accumulator is proposed. In the proposed system, the data size in the authentication is constant for parameters. Although the user’s computational cost depends on parameters, the dependent cost is O(δBL · K) multiplications, instead of exponentiations, where δBL is the number of sessions added to the blacklist after the last authentication of the user, and K is the number of past sessions of the user. The demerit of the proposed system is O(n)-size public key, where n corresponds to the total number of all sessions of all users in the system. But, the user only has to download the public key once.

Modified relay selection and circuit selection for faster Tor

Users of the Tor anonymity system suffer from less-than-ideal performance, in part because circuit building and selection processes are not tuned for speed. In this study, the authors examine both the process of selecting among pre-built circuits and the process of selecting the path of relays for use in building new circuits to improve performance while maintaining anonymity. First, the authors show that having three pre-built circuits available allows the Tor client to identify fast circuits and improves median time to first byte (TTFB) by 15% over congestion-aware routing, the current state-of-the-art method. Second, they propose a new path selection algorithm that includes broad geographic location information together with bandwidth to reduce delays. In shadow simulations, 20% faster median TTFB and 11% faster median total download times over congestion-aware routing for accessing web page-sized objects were found. The proposed security evaluations show that this approach leads to better or equal security against a generic relay-level adversary compared to Tor, but increased vulnerability to targeted attacks. The authors explore this trade-off and find settings of the proposed system that offers good performance, modestly better security against a generic adversary, and only slightly more vulnerability to a targeted adversary.

Lockmix: a secure and privacy-preserving mix service for Bitcoin anonymity

Bitcoin has attracted considerable attention from governments, banks, as well as researchers. However, Bitcoin is not a completely anonymous system. All transaction information in the Bitcoin system is published on the network and can be used to reveal the identity of the user by transaction correlation analysis. In this paper, a secure and privacy-preserving mix service for Bitcoin anonymity, Lockmix, is proposed. Lockmix introduces mix servers to provide a mix service for the user by using blind signature and multi-signature schemes to prevent attackers from linking the input address with the output address. Lockmix provides anonymity, scalability, accountability, Bitcoin compatibility and anti-theft. Lockmix has been implemented on a Bitcoin test network, and experiments show that our solution is efficient.

Fundamental Limits of Invisible Flow Fingerprinting

Network flow fingerprinting can be used to de-anonymize communications on anonymity systems such as Tor by linking the ingress and egress segments of anonymized connections. Assume Alice and Bob have access to the input and the output links of an anonymous network, respectively, and they wish to collaboratively reveal the connections between the input and the output links without being detected by Willie who protects the network. Alice generates a codebook where each codeword is a unique fingerprint indicating a sequence of interpacket delays, and shares it only with Bob. To trace each flow, Alice selects a fingerprint and manipulates the packet timings of the flow to follow the packet timings suggested by the fingerprint, and Bob extracts the fingerprints from it after it passes through the network. We model the network as parallel M/M/1 queues where each queue is shared by a flow f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> from Alice to Bob and other flows independent of f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> . Packet timings of the flows are governed by independent Poisson processes. Assuming all input flows have equal packet rates and that Bob observes only flows with fingerprints, we first present two scenarios: 1) Alice fingerprints all the flows and 2) Alice fingerprints a subset of the flows, unknown to Willie. Then, we extend the construction and analysis to the case of arbitrary flow rates and the case where Bob observes flows with and without fingerprints. For each scenario, we derive the number of flows that Alice and Bob can trace by fingerprinting.

PERSONALITY IN THE ERA OF POSTMODERNISM

The article is devoted to the analysis of the influence of the tendencies on the formation and political socialization of the individual. The author, relying on a comparative method, carries out an analysis of factors that determine the essence of historical processes in the era of modern and “postmodern”, as well as the essence of changes in the order of power relations and socio-political structuring of societies. The author notes that in the post-modern era, the traditional processes of socialization of the individual as “cultural inheritance” and “cultural interpretation” have undergone a radical transformation. Postmodern, who directed his power to de-etatization, deiherarhizatsiya, detolatarizatsiya and individualization of social systems, contributed to the personification of personality, self-determination and, at the same time, systemic alienation. Postmodernism has demonstrated the limited culturally centralism in the system, but the self-sufficiency of the creative as self-realization. Postmodern socialization goes not in the system, but existentially and antisystemically, demonstrating the plurality of forms of self-realization (in a subculture, in anti-culture, in traditional culture). That is, postmodernism has demonstrated the greater importance of the process over the system. The end of the postmodern era reveals the collapse of the social system: a chaotic, anonymous system collapses its boundaries, a person actively experiments (lonely in his alienation), but before it opens the social space of absolute freedom, which permits chaos to be perceived as a complex and unpredictable form of order, when any Some perspectives are multivariate as trails that run out of the garden. On the other hand, it is obvious that the collapse of social systems and the rules of socialization leads to the destruction of the mechanism of cultural perception, the value foundations that formed the basis of traditional humanism. And with the loss of transcendental, cultural meanings and values unfold in the plane of immanent. Personality in a chaotic system is subject to disintegration. The disintegration and dispersion of the I is accompanied by the search for a significant other, which, in the absence of a social system, becomes a virtual social system that provides information and cultural influence on the formation of personality settings. The main existential conflict is the conflict between freedom without restrictions and the absolute dependence on the power of information technology. This puts on the agenda the problem of finding the true semantic orientations of the individual and his responsibility for his destiny.

An Analysis of A Bidirectional School Nurse-Led Text-Messaging Service

Aim: To analyse a school nurse led bi-directional text messaging service provided to young people aged 11–19 in two inner London boroughs. Background: School nurses play a key role in providing early advice and support to the school-aged population. The ability to access a school nurse has been recognised by young people as something that needs to improve and suggestions of being able to text a school nurse have been made. ChatHealth is a bi-directional text messaging system that allows young people aged 11–19 to ask a school nurse for advice and support via an anonymous short messaging system (SMS). Arguably, ChatHealth offers more opportunities than traditional access methods to reach more young people. However, due to the relatively new concept, there is a limited evidence base regarding its effectiveness. Methods: An audit of documentary data was completed to analyse the uptake and outcomes of ChatHealth in the local area. Content analysis was carried out analysing 26 conversation transcripts and a staff questionnaire was distributed to gain a better understanding of the role of the school nurse delivering ChatHealth. Findings: The ChatHealth service appears to be proactive in offering an efficient response to a variety of physical, emotional, sexual health and appointment queries, additionally, the uptake of the service has supplemented the established face-to-face contacts. In the local area, emotional health is the most common type of query being received from young people and the topic school nurses feel least confident in responding to. School nurses identify the benefits of ChatHealth in improving young people's access and in enhancing the visibility of the school nursing service and did not identify it as an inconvenience to their current workload.

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 New Group Location Privacy-Preserving Method Based on Distributed Architecture in LBS

Nowadays, the location privacy problem has become an important problem for the users who enjoy the location-based services (LBSs). Researchers have focused on the problem of how to protect the location privacy of user efficiently for a long time. On one hand, many achievements adopt the centralized structure in which there is an additional center server. Additionally, some other researchers adopt the distributed structure to overcome the disadvantages brought by the center server in the centralized anonymous system structure. On the other hand, the existing methods of solving the problem are always to protect the individual user’s location privacy in LBSs, without considering the user group’s location privacy. This kind of methods is not very applicable to the status of a number of users who formed a group to complete a LBS task together by collaborative computing. In order to solve the problem of location privacy protection for a user group in the untrusted mobile social networks, a location privacy protection method based on the distributed structure is discussed in this paper. In the scheme, the special homomorphic features of BGN cryptosystem are cleverly used so that it can solve the group’s three classical location service applications simultaneously, namely, group nearest neighbor query, optimal group collection point determination, and group friend’s distance query, by only one security policy. If there are k users who formed the group, it could achieve k-anonymity without exposing the coordinate of each individual user or using any anonymous areas. Furthermore, theoretical and experimental analysis proves that the proposal can efficiently protect each user’s location privacy in the group through taking full advantage of the collaborative computing and communication capabilities of the mobile terminals. It can resist the existing distance interaction attack and collusion attack and can realize the secure and efficient fine-grained controllable location privacy protection for the user group.

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.

Flow Context and Host Behavior Based Shadowsocks’s Traffic Identification

Cloud Virtual Private Server (VPS) services provide the chance of rapid deployment of anonymous proxy services, becoming an important part of many anonymous proxy solutions. The anonymous system represented by ShadowSocks (SS), through proxy services deployed on VPSs provided by different cloud service providers, has become an important mean for illegal network activists to engage in illegal network activities such as cyber-attacks and darknet transactions. It is difficult for local network administrators to supervise SS traffic from the cloud. While from the local network, the task faces the challenges of Invisible Negotiation Process and Data Transparent Transmission. In this paper, we present a novel SS detection method based on flow context and host behavior. The method can not only accurately identify SS flows, but also be applicable to a large-scale network environment. In this method, we extract 12-dimensional features from three aspects: the relationship between flows, hosts' flow behavior, and hosts' DNS behavior to build the detection model. Among them, the four features about flow burst and the feature of unassociated domain names' number are innovatively proposed in this paper. Moreover, the big data statistical and association techniques are used in the method. To verify the effectiveness of the method, we first built a real SS running environment based on the campus network and two VPSs on two different public cloud platforms. Moreover, we conduct a series of experiments on the NTCI-BDP data platform which is a big data platform built by our team. The experimental results show that our method achieves 93.43% accuracy on experimental data sets and can effectively identify SS traffic.

Using Insider Swapping of Time Intervals to Perform Highly Invisible Network Flow Watermarking

Network flow watermarking (NFW) is an emerging flow correlation technique to deanonymize an anonymous communication system or detect stepping stones, in which a watermark is encoded into a network flow by manipulating some flow characteristics, predominantly by altering timing information. Although interval-based NFWs that employ time intervals as carrier have proven to be capable of resisting moderate network interference, they are vulnerable to some statistic-based attacks, which may expose the very existence of watermark and enable attackers to damage or remove watermark from the observed flow. In this study, using insider swapping of time intervals and an adaptive centroid quantization framework, we design a highly invisible NFW scheme, which is undetectable by multi-flow attacks (MFA), Kullback-Leibler divergence (KLD) test, Kolmogorov-Smirnov (K-S) test, and spread spectrum flow watermark (SSFW) detection. Experimental results using real traffic and public dataset show that the proposed NFW scheme can outperform three typical NFW schemes on invisibility while maintaining a strong interference-resistance capability of network jitter, packet loss, and dummy packet insertion.

Path selection algorithm with minimal delay in wireless sensor networks

With the rapid popularization and development of Internet, global researchers are increasingly paying more and more attention to anonymity and privacy security. Anonymous communication technology has gradually become people’s focus. Attacks against sensors may appear in different layers, so anonymity at network layer should therefore be envisioned. Tor, as one of the anonymous communication systems which implements multi-hop to protect user’s identity privacy on the Internet, is currently the most popular anonymous privacy solution, but the concept of Tor has not applied to wireless sensor networks. Therefore, in this article, we think the mix structure of Tor which is crucial to its anonymity can be applied to wireless sensor networks; what’s more, an improved path selecting algorithm according to round trip time we propose can boost some degree of performance. First, we make a summary of current typical path selection algorithms and analyze the performance and anonymity problems of these algorithms in network congestion. Then, in order to improve the performance of the algorithm in congestion, a routing improvement scheme based on round trip time is proposed.

Privacy-Preserved Pseudonym Scheme for Fog Computing Supported Internet of Vehicles

As a promising branch of Internet of Things, Internet of Vehicles (IoV) is envisioned to serve as an essential data sensing and processing platform for intelligent transportation systems. In this paper, we aim to address location privacy issues in IoV. In traditional pseudonym systems, the pseudonym management is carried out by a centralized way resulting in big latency and high cost. Therefore, we present a new paradigm named Fog computing supported IoV (F-IoV) to exploit resources at the network edge for effective pseudonym management. By utilizing abundant edge resources, a privacy-preserved pseudonym ( $P^{3}$ ) scheme is proposed in F-IoV. The pseudonym management in this scheme is shifted to specialized fogs at the network edge named pseudonym fogs, which are composed of roadside infrastructures and deployed in close proximity of vehicles. $P^{3}$ scheme has following advantages: 1) context-aware pseudonym changing; 2) timely pseudonym distribution; and 3) reduced pseudonym management overhead. Moreover, a hierarchical architecture for $P^{3}$ scheme is introduced in F-IoV. Enabled by the architecture, a context-aware pseudonym changing game and secure pseudonym management communication protocols are proposed. The security analysis shows that $P^{3}$ scheme provides secure communication and privacy preservation for vehicles. Numerical results indicate that $P^{3}$ scheme effectively enhances location privacy and reduces communication overhead for the vehicles.