Akira Otsuka

• Professor
• Professor (Full) at Institute of Information Security

Increasing attention to digital identity and self-sovereign identity (SSI) is gaining momentum. SSI brings various benefits to natural persons, such as owning controls; conversely, digital identity systems in the real world require Sybil-resistance to comply with anti-money laundering (AML) and other needs. CanDID by Maram et al. proposed that dece...

This article describes the idea of utilizing Attested Execution Secure Processors (AESPs) that fit into building a secure Self-Sovereign Identity (SSI) system satisfying Sybil-resistance under permissionless blockchains. Today's circumstances requiring people to be more online have encouraged us to address digital identity preserving privacy. There...

Bit-stream recognition (BSR) has a wide range of applications, including forensic investigations, detecting copyright infringement, and analyzing malware. In order to analyze file fragments recovered by digital forensics, it is necessary to use a BSR method that can accurately classify classes while addressing various domains without preprocessing...

Electronic cash (e-cash) systems need to satisfy the property of anonymity, unforgeability, and transparency which prevent criminal activities from abuse of anonymity. Observers proposed by Chaum et al. and Brands in the ’90 s are one of the cleverest solutions, where observers deployed by the authorities to the user’s device only engage in legitim...

Aim Malware family classification is critical for identifying unknown malware species, helping prevent infections, and making analysis more efficient. Existing studies have shown that Function Call Graphs (FCGs) can be used to classify malware types with high performance. However, the effectiveness of FCGs has yet to be thoroughly discussed, and it...

Binary code similarity detection is an effective analysis technique for vulnerability, bug, and plagiarism detection in software for which the source code cannot be obtained. The recent proliferation of IoT devices has also increased the demand for similarity detection across different architectures. However, there are currently not many examples o...

Bit-stream recognition (BSR) has many applications, such as forensic investigations, detection of copyright infringement, and malware analysis. We propose the first BSR that takes a bare input bit-stream and outputs a class label without any preprocessing. To achieve our goal, we propose a centrifuge mechanism, where the upstream layers (sub-net) c...

Binary code similarity comparison methods are mainly used to find bugs in software, to detect software plagiarism, and to reduce the workload during malware analysis. In this paper, we propose a method to compare the binary code similarity of each function by using a combination of Control Flow Graphs (CFGs) and disassembled instruction sequences c...

Micropayments are one of the challenges in cryptocurrencies. Micropayments on the blockchain have the problem that the fee is high for the transfer amount. As a countermeasure, a method called Layer-two has been proposed to consolidate transactions outside the blockchain and improve the blockchain’s throughput. As one of the existing Layer-two sche...

Micropayments are one of the challenges in cryptocurrencies. The problems in realizing micropayments in the blockchain are the low throughput and the high blockchain transaction fee. As a solution, decentralized probabilistic micropayment has been proposed. The winning amount is registered in the blockchain, and the tickets are issued to be won wit...

With increasing threats to information security, information security education through practical exercises specifically cyber range has attracted attention. However, the use of a cyber range is not widespread because of the high initial and maintenance cost and difficulty of developing new scenarios. Because many virtual instances are executed in...

A cyber range, a practical and highly educational information security exercise system, is difficult to implement in educational institutions because of the high cost of implementing and maintaining it. Therefore, there is a need for a cyber range that can be adopted and maintained at a low cost. Recently, container type virtualization is gaining a...

In this paper, we construct the Confidential and Auditable Payments (CAP) scheme. We keep the transaction confidential by writing ciphertexts of transactions in a ledger. We realize the soundness of the CAP scheme by the soundness of the zero-knowledge proof. A court or an authority controls a unique secret key of the ciphertexts written in the led...

Double-spending attacks on fast payments are one of the fatal architectural problems in Cryptocurrencies. Dmitrienko et al. proposed an offline fast payment scheme that relies on tamper-proof wallets produced by trustworthy manufacturers. With the wallets, the payee can immediately trust the transactions generated by the wallets without waiting for...

Malicious document files used in targeted attacks often contain a small program called shellcode. It is often hard to prepare a runnable environment for dynamic analysis of these document files because they exploit specific vulnerabilities. In these cases, it is necessary to identify the position of the shellcode in each document file to analyze it...

In this paper, we have achieved privacy protection and high transparency in a permissioned blockchain. There is a sidechain that connects the permissionless blockchain and the permissioned blockchain. The behavior in the permissioned blockchain is almost a black box from the perspective of the permissionless blockchain. While this fact is useful fo...

Malicious document files used in targeted attacks often contain a small program called shellcode. It is often hard to prepare a runnable environment for dynamic analysis of these document files because they exploit specific vulnerabilities. In these cases, it is necessary to identify the position of the shellcode in each document file to analyze it...

Anonymization is one of the major processes to protect location-based services (LBS) from privacy leakage. However, there are many discussions about de-anonymization attacks to LBS and whether anonymization processing is a sufficient countermeasure for privacy leakage. In this paper, we proposed a novel method to reconstruct the location of user co...

We analyze the theoretical vulnerability of maximum a poste-riori(MAP) speaker adaptation, which is widely used in practical speaker recognition systems. First, we proved that there exist a set of feature vectors, what are called wolves, which can impersonate almost all the registered speakers with probability asymptotically close to 1 with at most...

Presentation attack against biometric authentication systems is getting attention by many researchers since the seminal paper[4]. In this paper, we consider a new kind of presentation attack called wolf attack. Wolf attack does not require biometric feature from a victim which the other presentation attacks does but synthesizes biometric feature fr...

Impersonation by impostors is one of the representative security issues on biometric authentication system. A wolf attack is an attack on biometrics system using a wolf that can be falsely accepted as a match with multiple templates. False acceptance rate (FAR) which has been a conventional standard measure to quantify the average error rates of de...

Conventionally, almost all biometric authentication systems assume that impersonation attempts are conducted by human samples or artifacts resemble to human samples. Similarly, the security of biometric authentication systems is conventionally measured by false acceptance rate, the average probability of accepting impersonation attempts assuming bi...

Biometrics is a key technology for the authentication of individuals. As far as malicious impersonation attempt cannot be put an end, security is essential for biometric authentication systems. The security of biometric authentication systems is conventionally measured by false acceptance rate (FAR), the average probability of falsely accepting an...

The security of biometric authentication systems against impersonation attack is usually evaluated by the false accept rate, FAR. The false accept rate FAR is a metric for zero-effort impersonation attack assuming that the attacker attempts to impersonate a user by presenting his own biometric sample to the system. However, when the attacker has so...

Many biometric template protection algorithms have been proposed mainly in two approaches: biometric feature transformation and biometric cryptosystem. Security evaluation of the proposed algorithms are often conducted in various inconsistent manner. Thus, it is strongly demanded to establish the common evaluation metrics for easier comparison amon...

Recently Radio Frequency IDentiflcation (RFID) systems are used in many applications. However an individual identification scheme using RFID tags has a serious problem that if there are many tags within the reader's operation range, then the reader can not determine a genuine tag of a user to be authenticated, the identification protocol is execute...

Explosive progress in networking and outsourcing storage increases the use of information retrieval technologies, in massive datasets. Nowadays, there are varieties of storage-providers through the internet, such as e-mail accounts and public database, which are convenient to store and exchange electronic files and medias. Typically, the storage-pr...

Cancelable approaches for biometric person authentication have been studied to protect enrolled biometric data, and several algorithms have been proposed. One drawback of cancelable approaches is that the performance is inferior to that of non-cancelable approaches. In this paper, we propose a scheme to improve the performance of a cancelable appro...

Wolf attack is a new kind of biometric specific vulnerability and wolf attack probability is defined as a maximum success probability of the wolf attack with one wolf sample. From a theoretical point of view, a possible approach for describing wolf attack probability has been proposed in recent years, yet very little is known about practical approa...

Cancelable approaches for biometric person authentication have been studied to protect enrolled biometric data, and several algorithms have been proposed. One drawback of cancelable approaches is that the performance is inferior to that of non-cancelable approaches. As one solution, we proposed a scheme to enhance the performance of a cancelable ap...

Governments and international standards bodies have established certification procedures for security-critical technologies, such as cryptographic algorithms. Such standards have not yet been established for cryptographic protocols and hence it is difficult for users of these protocols to know whether they are trustworthy. This is a serious problem...

In this chapter, we will show how to achieve unconditional or information-theoretic security in electronic voting with the following property: 1 Even all voters and tallying authorities have unbounded computing power, the distorted integrity of the voting results can be detected and proved incorrect by every honest voter, 1 If at least one tallying...

In an overview paper called State of the Art: Embedding Security in Vehicles, Wolf et al. give a general state-of- the-art overview of IT security in vehicles and describe core security technologies and relevant security mechanisms. In this paper we show that a formal analysis of many of the related properties is possible. This indicates that many...

We propose a matching algorithm secure against the wolf attack in one-to-one biometric authentications. Our proposed algorithm embeds a wolf-judgement function in a traditional matching algorithm. We show that our proposed algorithm is accurate and secure. Moreover we remark that our proposed algorithm is efficient in a framework proposed by Inuma,...

In this paper, we propose a theoretical framework to construct matching algorithms for any biometric authentication systems. Conventional matching algorithms are not necessarily secure against strong intentional impersonation attacks such as wolf attacks. The wolf attack is an attempt to impersonate a genuine user by presenting a "wolf" to a biomet...

In this paper, we propose a theoretical framework to construct matching algorithms for any biometric authentication systems. Conventional matching algorithms are not necessarily secure against strong intentional impersonation attacks such as wolf attacks. The wolf attack is an attempt to impersonate a genuine user by presenting a "wolf" to a biomet...

This paper presents a novel security architecture for in-vehicle communication. The ratio of electronics to vehicle equipment is steadily increasing. And novel vehicles will also have connectibility to public networks to provide many kinds of services. Therefore, they are expected to suffer from a wide variety of threats and the electronic control...

Oblivious polynomial evaluation (OPE) consists of a two-party protocol where a sender inputs a polynomial \(p(x)\) and a receiver inputs a single value \(x_{0}\) . At the end of the protocol, the sender learns nothing and the receiver learns \(p(x_{0})\) . This paper deals with the problem of oblivious polynomial evaluation under an information-the...

This paper presents a non-interactive veriable secret shar- ing scheme (VSS) tolerating a dishonest majority based on data pre- distributed by a trusted authority. As an application of this VSS scheme we present very ecient unconditionally secure multiparty protocols based on pre-distributed data which generalize two-party computations based on lin...

The Probe Vehicle Information system is as system that collects information from cars equipped with sensors. Usually, various information is collected and transferred to a server, at frequent intervals. The information includes when and where the information was collected, which could lead to privacy problems. One way to solve these problems, is to...

This paper will propose a wolf attack probability ( WAP ) as a new measure for evaluating security of biometric authentication systems. The wolf attack is an attempt to impersonate a victim by feeding “wolves” into the system to be attacked. The “wolf” means an input value which can be falsely accepted as a match with multiple templates. WAP is def...

Most electronic cash systems being deployed look very different from what academics have been envisioning over the last 3 decades. Experts on the panel gave different definitions for electronic cash, surveyed systems deployed in some countries, discussed reliability, privacy and security concerns. Moreover, electronic cash and advertisements were l...

This paper will propose a wolf attack probability (W AP ) as a new measure for evaluating security of biometric authentication sys- tems. The wolf attack is an attempt to impersonate a victim by feeding "wolves" into the system to be attacked. The "wolf" means an input value which can be falsely accepted as a match with multiple templates. W AP is...

Provision of context-dependent services is triggered when the context satisfies an execution condition. To deliver these services, users’ contexts have to be determined by terminals such as GPS. However, GPS has efficiency (it must collect as many contexts as possible to provide services appropriately) and privacy problems (all data is concentrated...

In this paper, we survey the recent research results on privacy-preserving Identification suitable for limited-resource devices such as RFID, contactless smartcards, and introduce our recent results on a light-weight privacy-preserving identification scheme. The proposed scheme only requires (1) random bit generators, (2) simple bit-wise operations...

The first refreshable anonymous token scheme proposed in [l] enables one to provide services in such a way that each of its users is allowed to enjoy only a fixed number of services at the same time. In this paper, we show that the scheme in [l] is insecure and propose a provably secure refreshable partial anonymous token scheme which is a generali...

We introduce an information theoretical model for oblivious polynomial evaluation relying on predistributed data, and prove very general lower bounds on the size of the predistributed data, as well as the size of the communications in any (one-round) protocol. We then show that these bounds are tight by exhibiting a scheme for oblivious polynomial...

This paper presents a non-interactive verifiable secret sharing scheme (VSS) tolerating a dishonest majority based on data predistributed by a trusted authority. As an application of this VSS scheme we present very efficient unconditionally secure multiparty protocols based on predistributed data which generalize two-party computations based on lin...

Anonymity is a highly desired feature in Internet transactions. On the other hand, unconditional anonymity may contain some traps. For instance, it may cause irresponsible, or even criminal, use of the Internet. Thus, it would be desirable to have revocable anonymity in our internet applications. In this work, we suggest an anonymous authentication...

We study the problem of secure function evaluation in the so called commodity based cryptography model as proposed by Beaver in his STOC 97 paper. We propose very efficient protocols for implement- ing addition and multiplication over GF (q). Differently than in previous works, in our protocol each step of the computation is verifiable. More- over,...

In this paper we deal with unconditionally secure commitment schemes based on pre-distributed data. We provide bounds for the amount of data which has to be pre-distributed to the participants of the commitment, thus solving an open problem stated in the literature. We also introduce the issue of homomorphism in unconditionally secure commitment sc...

Summary form only given. We discuss information-theoretic methods to prove the security of cryptosystems. We study what is called, unconditionally secure (or information-theoretically secure) cryptographic schemes in search for a system that can provide long-term security and that does not impose limits on the adversary's computational power.

Recently, paper based transactions are being replaced by digitized transactions in a rapid pace. These kinds of digitized data are useful compared to paper based data in the sense of the flexibility of the data. Loan services, (for example, Library, Rental video, debt etc., ) are among the services that makes use of sophisticated digitized transact...

We have introduced the first electronic cash scheme with unconditional security. That is, even malicious users with unlimited computational ability cannot forge a coin and cannot change user's identity secretly embedded in each coin. While. the spender's anonymity is preserved by our new blind signature scheme based on unconditionally secure signat...

In (4), we proposed a theoretical framework to construct matching algorithms for any biometric authentication systems. In this paper, we will introduce the results in (4) and add some comments on the accuracy (FAR and FRR) of our proposed matching algorithms (Lemma 6, 7, 8). Conventional matching algorithms are not necessarily secure against strong...