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Research Collection School Of Computing and Information Systems

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Evaluation Of Different Electronic Product Code Discovery Service Models, Su Mon Kywe, Jie Shi, Yingjiu Li, Raghuwanshi Kailash Apr 2012

Evaluation Of Different Electronic Product Code Discovery Service Models, Su Mon Kywe, Jie Shi, Yingjiu Li, Raghuwanshi Kailash

Research Collection School Of Computing and Information Systems

Electronic Product Code Discovery Service (EPCDS) is an important concept in supply chain processes and in Internet of Things (IOT). It allows supply chain participants to search for their partners, communicate with them and share product information using standardized interfaces securely. Many researchers have been proposing different EPCDS models, considering different requirements. In this paper, we describe existing architecture designs of EPCDS systems, namely Directory Service Model, Query Relay Model and Aggregating Discovery Service Model (ADS). We also briefly mention Secure Discovery Service (SecDS) Model, which is an improved version of Directory Service Model with a secure attribute-based access control …


Hasbe: A Hierarchical Attribute-Based Solution For Flexible And Scalable Access Control In Cloud Computing, Zhiguo Wan, Jun'e Liu, Robert H. Deng Apr 2012

Hasbe: A Hierarchical Attribute-Based Solution For Flexible And Scalable Access Control In Cloud Computing, Zhiguo Wan, Jun'e Liu, Robert H. Deng

Research Collection School Of Computing and Information Systems

Cloud computing has emerged as one of the most influential paradigms in IT industry in recent years. Since this new computing technology requires users to entrust their valuable data to cloud providers, there have been increasing security and privacy concerns on outsourced data. Several schemes employing attribute-based encryption (ABE) have been proposed for access control of outsourced data in cloud computing; however, most of them suffer from inflexibility in implementing complex access control policies. In order to realize scalable, flexible, and fine-grained access control of outsourced data in cloud computing, in this paper we propose hierarchical attribute-set-based encryption (HASBE) by …


A Comparative Study Of Cyberattacks, Seung Hyun Kim, Qiu-Hong Wang, Johannes B. Ullrich Mar 2012

A Comparative Study Of Cyberattacks, Seung Hyun Kim, Qiu-Hong Wang, Johannes B. Ullrich

Research Collection School Of Computing and Information Systems

Cyberattacks are computer-to-computer attacks undermining the confidentiality, integrity, and/or availability of computers and/or the information they hold. The importance of securing cyberspace is increasing, along with the sophistication and potential significance of the results of the attacks. Moreover, attacksb involve increasingly sophisticated coordination among multiple hackers across international boundaries, where the aim has shifted from fun and self-satisfaction to financial or military gain, with clear and self-reinforcing motivation; for example, the number of new malicious code threats worldwide increased more than 71% from 2008 to 2009.


Human: Creating Memorable Fingerprints Of Mobile Users, Gupta Payas, Kiat Wee Tan, Narayanasamy Ramasubbu, David Lo, Debin Gao, Rajesh Krishna Balan Mar 2012

Human: Creating Memorable Fingerprints Of Mobile Users, Gupta Payas, Kiat Wee Tan, Narayanasamy Ramasubbu, David Lo, Debin Gao, Rajesh Krishna Balan

Research Collection School Of Computing and Information Systems

In this paper, we present a new way of generating behavioral (not biometric) fingerprints from the cellphone usage data. In particular, we explore if the generated behavioral fingerprints are memorable enough to be remembered by end users. We built a system, called HuMan, that generates fingerprints from cellphone data. To test HuMan, we conducted an extensive user study that involved collecting about one month of continuous usage data (including calls, SMSes, application usage patterns etc.) from 44 Symbian and Android smartphone users. We evaluated the memorable fingerprints generated from this rich multi-context data by asking each user to answer various …


Secds: A Secure Epc Discovery Services System In Epcglobal Network, Jie Shi, Darren Sim, Yingjiu Li, Robert H. Deng Feb 2012

Secds: A Secure Epc Discovery Services System In Epcglobal Network, Jie Shi, Darren Sim, Yingjiu Li, Robert H. Deng

Research Collection School Of Computing and Information Systems

In recent years, the Internet of Things (IOT) has drawn considerable attention from the industrial and research communities. Due to the vast amount of data generated through IOT devices and users, there is an urgent need for an effective search engine to help us make sense of this massive amount of data. With this motivation, we begin our initial works on developing a secure and efficient search engine (SecDS) based on EPC Discovery Services (EPCDS) for EPCglobal network, an integral part of IOT. SecDS is designed to provide a bridge between different partners of supply chains to share information while …


A New Efficient Optimistic Fair Exchange Protocol Without Random Oracles, Qiong Huang, Guomin Yang, Duncan S. Wong, Willy Susilo Jan 2012

A New Efficient Optimistic Fair Exchange Protocol Without Random Oracles, Qiong Huang, Guomin Yang, Duncan S. Wong, Willy Susilo

Research Collection School Of Computing and Information Systems

Optimistic fair exchange (OFE) is a kind of protocols to solve the problem of fair exchange between two parties. Most of the previous work on this topic are provably secure in the random oracle model. In this work, we propose a new construction of OFE from another cryptographic primitive, called time capsule signature. The construction is efficient and brings almost no overhead other than the primitive itself. The security of our new construction is based on that of the underlying primitive without relying on the random oracle heuristic. Applying our generic construction to the time capsule signature scheme recently proposed …


A Survey On Privacy Frameworks For Rfid Authentication, Chunhua Su, Yingjiu Li, Yunlei Zhao, Robert H. Deng, Yiming Zhao, Jianying Zhou Jan 2012

A Survey On Privacy Frameworks For Rfid Authentication, Chunhua Su, Yingjiu Li, Yunlei Zhao, Robert H. Deng, Yiming Zhao, Jianying Zhou

Research Collection School Of Computing and Information Systems

Due to rapid growth of RFID system applications, the security and privacy problems become more and more important to guarantee the validity of RFID systems. Without introducing proper privacy protection mechanisms, widespread deployment of RFID could raise privacy concerns to both companies and individuals. As a fundamental issue for the design and analysis of secure RFID systems, some formal RFID privacy frameworks were proposed in recent years to give the principles for evaluating the security and privacy in RFID system. However, readers can be confused with so many proposed frameworks. In this paper, we make a comparative and survey study …


Dynamic Secure Cloud Storage With Provenance, Sherman S. M. Chow, Cheng-Kang Chu, Xinyi Huang, Jianying Zhou, Robert H. Deng Jan 2012

Dynamic Secure Cloud Storage With Provenance, Sherman S. M. Chow, Cheng-Kang Chu, Xinyi Huang, Jianying Zhou, Robert H. Deng

Research Collection School Of Computing and Information Systems

One concern in using cloud storage is that the sensitive data should be confidential to the servers which are outside the trust domain of data owners. Another issue is that the user may want to preserve his/her anonymity in the sharing or accessing of the data (such as in Web 2.0 applications). To fully enjoy the benefits of cloud storage, we need a confidential data sharing mechanism which is fine-grained (one can specify who can access which classes of his/her encrypted files), dynamic (the total number of users is not fixed in the setup, and any new user can decrypt …


On Two Rfid Privacy Notions And Their Relations, Yingjiu Li, Robert H. Deng, Junzuo Lai, Changshe Ma Dec 2011

On Two Rfid Privacy Notions And Their Relations, Yingjiu Li, Robert H. Deng, Junzuo Lai, Changshe Ma

Research Collection School Of Computing and Information Systems

Privacy of RFID systems is receiving increasing attention in the RFID community. Basically, there are two kinds of RFID privacy notions in the literature: one based on the indistinguishability of two tags, denoted as ind-privacy, and the other based on the unpredictability of the output of an RFID protocol, denoted as unp*-privacy. In this article, we first revisit the existing unpredictability-based RFID privacy models and point out their limitations. We then propose a new RFID privacy model, denoted as unp*-privacy, based on the indistinguishability of a real tag and a virtual tag. We formally clarify its relationship with the ind-privacy …


Understanding And Protecting Privacy: Formal Semantics And Principled Audit Mechanisms, Anupam Datta, Jeremiah Blocki, Nicolas Christin, Henry Deyoung, Deepak Garg, Limin Jia, Dilsun Kaynar, Arunesh Sinha Dec 2011

Understanding And Protecting Privacy: Formal Semantics And Principled Audit Mechanisms, Anupam Datta, Jeremiah Blocki, Nicolas Christin, Henry Deyoung, Deepak Garg, Limin Jia, Dilsun Kaynar, Arunesh Sinha

Research Collection School Of Computing and Information Systems

Privacy has become a significant concern in modern society as personal information about individuals is increasingly collected, used, and shared, often using digital technologies, by a wide range of organizations. Certain information handling practices of organizations that monitor individuals’ activities on the Web, data aggregation companies that compile massive databases of personal information, cell phone companies that collect and use location data about individuals, online social networks and search engines—while enabling useful services—have aroused much indignation and protest in the name of privacy. Similarly, as healthcare organizations are embracing electronic health record systems and patient portals to enable patients, employees, …


Automated Removal Of Cross Site Scripting Vulnerabilities In Web Applications, Lwin Khin Shar, Hee Beng Kuan Tan Dec 2011

Automated Removal Of Cross Site Scripting Vulnerabilities In Web Applications, Lwin Khin Shar, Hee Beng Kuan Tan

Research Collection School Of Computing and Information Systems

Context: Cross site scripting (XSS) vulnerability is among the top web application vulnerabilities according to recent surveys. This vulnerability occurs when a web application uses inputs received from users in web pages without properly checking them. This allows an attacker to inject malicious scripts in web pages via such inputs such that the scripts perform malicious actions when a client visits the exploited web pages. Such an attack may cause serious security violations such as account hijacking and cookie theft. Current approaches to mitigate this problem mainly focus on effective detection of XSS vulnerabilities in the programs or prevention of …


Launching Return-Oriented Programming Attacks Against Randomized Relocatable Executables, Limin Liu, Jin Han, Debin Gao, Jiwu Jing, Daren Zha Nov 2011

Launching Return-Oriented Programming Attacks Against Randomized Relocatable Executables, Limin Liu, Jin Han, Debin Gao, Jiwu Jing, Daren Zha

Research Collection School Of Computing and Information Systems

Since the day it was proposed, return-oriented programming has shown to be an effective and powerful attack technique against the write or execute only (W ⊕ X) protection. However, a general belief in the previous research is, systems deployed with address space randomization where the executables are also randomized at run-time are able to defend against return-oriented programming, as the addresses of all instructions are randomized. In this paper, we show that due to the weakness of current address space randomization technique, there are still ways of launching return-oriented programming attacks against those well-protected systems efficiently. We demonstrate and evaluate …


Applying Time-Bound Hierarchical Key Assignment In Wireless Sensor Networks, Wentao Zhu, Robert H. Deng, Jianying Zhou, Feng Bao Nov 2011

Applying Time-Bound Hierarchical Key Assignment In Wireless Sensor Networks, Wentao Zhu, Robert H. Deng, Jianying Zhou, Feng Bao

Research Collection School Of Computing and Information Systems

Access privileges in distributed systems can be effectively organized as a partial-order hierarchy that consists of distinct security classes, and are often designated with certain temporal restrictions. The time-bound hierarchical key assignment problem is to assign distinct cryptographic keys to distinct security classes according to their privileges so that users from a higher class can use their class key to derive the keys of lower classes, and these keys are time-variant with respect to sequentially allocated temporal units called time slots. In this paper, we explore applications of time-bound hierarchical key assignment in a wireless sensor network environment where there …


Profit-Maximizing Firm Investments In Customer Information Security, Yong Yick Lee, Robert J. Kauffman, Ryan Sougstad Nov 2011

Profit-Maximizing Firm Investments In Customer Information Security, Yong Yick Lee, Robert J. Kauffman, Ryan Sougstad

Research Collection School Of Computing and Information Systems

When a customer interacts with a firm, extensive personal information often is gathered without the individual's knowledge. Significant risks are associated with handling this kind of information. Providing protection may reduce the risk of the loss and misuse of private information, but it imposes some costs on both the firm and its customers. Nevertheless, customer information security breaches still may occur. They have several distinguishing characteristics: (1) typically it is hard to quantify monetary damages related to them; (2) customer information security breaches may be caused by intentional attacks, as well as through unintentional organizational and customer behaviors; and (3) …


General Construction Of Chameleon All-But-One Trapdoor Functions, Shengli Liu, Junzuo Lai, Robert H. Deng Oct 2011

General Construction Of Chameleon All-But-One Trapdoor Functions, Shengli Liu, Junzuo Lai, Robert H. Deng

Research Collection School Of Computing and Information Systems

Lossy trapdoor functions enable black-box construction of public key encryption (PKE) schemes secure against chosen-ciphertext attack [18]. Recently, a more efficient black-box construction of public key encryption was given in [12] with the help of chameleon all-but-one trapdoor functions (ABO-TDFs).In this paper, we propose a black-box construction for transforming any ABO-TDFs into chameleon ABO-TDFs with the help of chameleon hash functions. Instantiating the proposed general black-box construction of chameleon ABO-TDFs, we can obtain the first chameleon ABO-TDFs based on the Decisional Diffie-Hellman (DDH) assumption.


Adaptive Collision Resolution For Efficient Rfid Tag Identification, Yung-Chun Chen, Kuo-Hui Yeh, Nai-Wei Lo, Yingjiu Li, Enrico Winata Oct 2011

Adaptive Collision Resolution For Efficient Rfid Tag Identification, Yung-Chun Chen, Kuo-Hui Yeh, Nai-Wei Lo, Yingjiu Li, Enrico Winata

Research Collection School Of Computing and Information Systems

In large-scale RFID systems, all of the communications between readers and tags are via a shared wireless channel. When a reader intends to collect all IDs from numerous existing tags, a tag identification process is invoked by the reader to collect the tags' IDs. This phenomenon results in tag-to-reader signal collisions which may suppress the system performance greatly. To solve this problem, we design an efficient tag identification protocol in which a significant gain is obtained in terms of both identification delay and communication overhead. A k-ary tree-based abstract is adopted in our proposed tag identification protocol as underlying architecture …


Packed, Printable, And Polymorphic Return-Oriented Programming, Kangjie Lu, Dabi Zou, Weiping Wen, Debin Gao Sep 2011

Packed, Printable, And Polymorphic Return-Oriented Programming, Kangjie Lu, Dabi Zou, Weiping Wen, Debin Gao

Research Collection School Of Computing and Information Systems

Return-oriented programming (ROP) is an attack that has been shown to be able to circumvent W ⊕ X protection. However, it was not clear if ROP can be made as powerful as non-ROP malicious code in other aspects, e.g., be packed to make static analysis difficult, be printable to evade non-ASCII filtering, be polymorphic to evade signature-based detection, etc. Research in these potential advances in ROP is important in designing counter-measures. In this paper, we show that ROP code could be packed, printable, and polymorphic. We demonstrate this by proposing a packer that produces printable and polymorphic ROP code. It …


Linear Obfuscation To Combat Symbolic Execution, Zhi Wang, Jiang Ming, Chunfu Jia, Debin Gao Sep 2011

Linear Obfuscation To Combat Symbolic Execution, Zhi Wang, Jiang Ming, Chunfu Jia, Debin Gao

Research Collection School Of Computing and Information Systems

Trigger-based code (malicious in many cases, but not necessarily) only executes when specific inputs are received. Symbolic execution has been one of the most powerful techniques in discovering such malicious code and analyzing the trigger condition. We propose a novel automatic malware obfuscation technique to make analysis based on symbolic execution difficult. Unlike previously proposed techniques, the obfuscated code from our tool does not use any cryptographic operations and makes use of only linear operations which symbolic execution is believed to be good in analyzing. The obfuscated code incorporates unsolved conjectures and adds a simple loop to the original code, …


On Detection Of Erratic Arguments, Jin Han, Qiang Yan, Robert H. Deng, Debin Gao Sep 2011

On Detection Of Erratic Arguments, Jin Han, Qiang Yan, Robert H. Deng, Debin Gao

Research Collection School Of Computing and Information Systems

Due to the erratic nature, the value of a function argument in one normal program execution could become illegal in another normal execution context. Attacks utilizing such erratic arguments are able to evade detections as fine-grained context information is unavailable in many existing detection schemes. In order to obtain such fine-grained context information, a precise model on the internal program states has to be built, which is impractical especially monitoring a closed source program alone. In this paper, we propose an intrusion detection scheme which builds on two diverse programs providing semantically-close functionality. Our model learns underlying semantic correlation of …


Towards Ground Truthing Observations In Gray-Box Anomaly Detection, Jiang Ming, Haibin Zhang, Debin Gao Sep 2011

Towards Ground Truthing Observations In Gray-Box Anomaly Detection, Jiang Ming, Haibin Zhang, Debin Gao

Research Collection School Of Computing and Information Systems

Anomaly detection has been attracting interests from researchers due to its advantage of being able to detect zero-day exploits. A gray-box anomaly detector first observes benign executions of a computer program and then extracts reliable rules that govern the normal execution of the program. However, such observations from benign executions are not necessarily true evidences supporting the rules learned. For example, the observation that a file descriptor being equal to a socket descriptor should not be considered supporting a rule governing the two values to be the same. Ground truthing such observations is a difficult problem since it is not …


Tamper Detection In The Epc Network Using Digital Watermarking, Shui-Hua Han, Chao-Hsien Chu, Zongwei Luo Sep 2011

Tamper Detection In The Epc Network Using Digital Watermarking, Shui-Hua Han, Chao-Hsien Chu, Zongwei Luo

Research Collection School Of Computing and Information Systems

One of the most relevant problems in radio frequency identification (RFID) technology is the lack of security measures in its wireless communication channel between the reader and tag. This article analyzes potential data tampering threats in the electronic product code (EPC) network and proposes solutions using fragile watermarking technologies.


Improved Ordinary Measure And Image Entropy Theory Based Intelligent Copy Detection Method, Dengpan Ye, Longfei Ma, Lina Wang, Robert H. Deng Sep 2011

Improved Ordinary Measure And Image Entropy Theory Based Intelligent Copy Detection Method, Dengpan Ye, Longfei Ma, Lina Wang, Robert H. Deng

Research Collection School Of Computing and Information Systems

Nowadays, more and more multimedia websites appear in social network. It brings some security problems, such as privacy, piracy, disclosure of sensitive contents and so on. Aiming at copyright protection, the copy detection technology of multimedia contents becomes a hot topic. In our previous work, a new computer-based copyright control system used to detect the media has been proposed. Based on this system, this paper proposes an improved media feature matching measure and an entropy based copy detection method. The Levenshtein Distance was used to enhance the matching degree when using for feature matching measure in copy detection. For entropy …


Privacy Beyond Single Sensitive Attribute, Yuan Fang, Mafruz Zaman Ashrafi, See Kiong Ng Sep 2011

Privacy Beyond Single Sensitive Attribute, Yuan Fang, Mafruz Zaman Ashrafi, See Kiong Ng

Research Collection School Of Computing and Information Systems

Publishing individual specific microdata has serious privacy implications. The k-anonymity model has been proposed to prevent identity disclosure from microdata, and the work on ℓ-diversity and t-closeness attempt to address attribute disclosure. However, most current work only deal with publishing microdata with a single sensitive attribute (SA), whereas real life scenarios often involve microdata with multiple SAs that may be multi-valued. This paper explores the issue of attribute disclosure in such scenarios. We propose a method called CODIP (Complete Disjoint Projections) that outlines a general solution to deal with the shortcomings in a naïve approach. We also introduce two measures, …


Certificateless Cryptography With Kgc Trust Level 3, Guomin Yang, Chik How Tan Sep 2011

Certificateless Cryptography With Kgc Trust Level 3, Guomin Yang, Chik How Tan

Research Collection School Of Computing and Information Systems

A normal certificateless cryptosystem can only achieve KGC trust level 2 according to the trust hierarchy defined by Girault. Although in the seminal paper introducing certificateless cryptography, Al-Riyami and Paterson introduced a binding technique to lift the KGC trust level of their certificateless schemes to level 3, many subsequent work on certificateless cryptography just focused on the constructions of normal certificateless schemes, and a formal study on the general applicability of the binding technique to these existing schemes is still missing. In this paper, to address the KGC trust level issue, we introduce the notion of Key Dependent Certificateless Cryptography …


Driverguard: A Fine-Grained Protection On I/O Flow, Yueqiang Cheng, Xuhua Ding, Robert H. Deng Sep 2011

Driverguard: A Fine-Grained Protection On I/O Flow, Yueqiang Cheng, Xuhua Ding, Robert H. Deng

Research Collection School Of Computing and Information Systems

Most commodity peripheral devices and their drivers are geared to achieve high performance with security functions being opted out. The absence of security measures invites attacks on the I/O data and consequently threats those applications feeding on them, such as biometric authentication. In this paper, we present the design and implementation of DriverGuard, a hypervisor based protection mechanism which dynamically shields I/O flows such that I/O data are not exposed to the malicious kernel. Our design leverages a composite of cryptographic and virtualization techniques to achieve fine-grained protection. DriverGuard is lightweight as it only needs to protect around 2% of …


General Construction Of Chameleon All-But-One Trapdoor Functions, Shengli Liu, Junzuo Lai, Robert H. Deng Aug 2011

General Construction Of Chameleon All-But-One Trapdoor Functions, Shengli Liu, Junzuo Lai, Robert H. Deng

Research Collection School Of Computing and Information Systems

Lossy trapdoor functions enable black-box construction of public key encryption (PKE) schemes secure against chosen-ciphertext attack [18]. Recently, a more efficient black-box construction of public key encryption was given in [13] with the help of chameleon all-but-one trapdoor functions (ABO-TDFs). In this paper, we propose a black-box construction for transforming any ABO-TDFs into chameleon ABO-TDFs with the help of chameleon hash functions. Instantiating the proposed general black-box construction of chameleon ABO-TDFs, we obtain the first chameleon ABO-TDFs based on the Decisional Diffie-Hellman (DDH) assumption.


A Generic Framework For Three-Factor Authentication: Preserving Security And Privacy In Distributed Systems, Xinyi Huang, Yang Xiang, Ashley Chonka, Jianying Zhou, Robert H. Deng Aug 2011

A Generic Framework For Three-Factor Authentication: Preserving Security And Privacy In Distributed Systems, Xinyi Huang, Yang Xiang, Ashley Chonka, Jianying Zhou, Robert H. Deng

Research Collection School Of Computing and Information Systems

As part of the security within distributed systems, various services and resources need protection from unauthorized use. Remote authentication is the most commonly used method to determine the identity of a remote client. This paper investigates a systematic approach for authenticating clients by three factors, namely password, smart card, and biometrics. A generic and secure framework is proposed to upgrade two-factor authentication to three-factor authentication. The conversion not only significantly improves the information assurance at low cost but also protects client privacy in distributed systems. In addition, our framework retains several practice-friendly properties of the underlying two-factor authentication, which we …


Defending Against Cross Site Scripting Attacks, Lwin Khin Shar, Hee Beng Kuan Tan Aug 2011

Defending Against Cross Site Scripting Attacks, Lwin Khin Shar, Hee Beng Kuan Tan

Research Collection School Of Computing and Information Systems

Researchers have proposed multiple solutions to cross-site scripting, but vulnerabilities continue to exist in many Web applications due to developers' lack of understanding of the problem and their unfamiliarity with current defenses' strengths and limitations.


Cryptanalysis Of Hsiang-Shih's Authentication Scheme For Multi-Server Architecture, Kuo-Hui Yeh, Nai-Wei Lo, Yingjiu Li Jul 2011

Cryptanalysis Of Hsiang-Shih's Authentication Scheme For Multi-Server Architecture, Kuo-Hui Yeh, Nai-Wei Lo, Yingjiu Li

Research Collection School Of Computing and Information Systems

From user point of view, password-based remote user authentication technique is one of the most convenient and easy-to-use mechanisms to provide necessary security on system access. As the number of computer crimes in modern cyberspace has increased dramatically, the robustness of password-based authentication schemes has been investigated by industries and organizations in recent years. In this paper, a well-designed password-based authentication protocol for multi-server communication environment, introduced by Hsiang and Shih, is evaluated. Our security analysis indicates that their scheme is insecure against session key disclosure, server spoofing attack, and replay attack and behavior denial.


Preserving Transparency And Accountability In Optimistic Fair Exchange Of Digital Signatures, Xinyi Huang, Yi Mu, Willy Susilo, Jianying Zhou, Robert H. Deng Jun 2011

Preserving Transparency And Accountability In Optimistic Fair Exchange Of Digital Signatures, Xinyi Huang, Yi Mu, Willy Susilo, Jianying Zhou, Robert H. Deng

Research Collection School Of Computing and Information Systems

Optimistic fair exchange (OFE) protocols are useful tools for two participants to fairly exchange items with the aid of a third party who is only involved if needed. A widely accepted requirement is that the third party's involvement in the exchange must be transparent, to protect privacy and avoid bad publicity. At the same time, a dishonest third party would compromise the fairness of the exchange and the third party thus must be responsible for its behaviors. This is achieved in OFE protocols with another property called accountability. It is unfortunate that the accountability has never been formally studied in …