IoT-REX: A Secure Remote-Control System for IoT Devices from Centralized Multi-Designated Verifier Signatures

IoT technology has been developing rapidly, while at the same time, notorious IoT malware such as Mirai is a severe and inherent threat. We believe it is essential to consider systems that enable us to remotely control infected devices in order to prevent or limit malicious behaviors of infected devices. In this paper, we design a promising candidate for such remote-control systems, called IoT-REX (REmote-Control System for IoT devices). IoT-REX allows a systems manager to designate an arbitrary subset of all IoT devices in the system and every device can confirm whether or not the device itself was designated; if so, the device executes a command given from the systems manager. Towards realizing IoT-REX, we introduce a novel cryptographic primitive called centralized multi-designated verifier signatures (CMDVS). Although CMDVS works under a restricted condition compared to conventional MDVS, it is sufficient for realizing IoT-REX. We provide an efficient CMDVS construction from any approximate membership query structures and digital signatures, yielding compact communication sizes and efficient verification procedures for IoT-REX. We then discuss the feasibility of IoT-REX through cryptographic implementation of the CMDVS construction on a Raspberry Pi. Our promising results demonstrate that the CMDVS construction can compress communication size to about 30% and thus its resulting IoT-REX becomes three times faster than a trivial construction over typical low-power wide area networks with an IoT device. It is expected that IoT-REX can control 12,000 devices within a second.Comment: Updated as a whole. 26 page

Studies on the Discharge at Water-intake Structure

This head work is the water-intake structure, by which irrigation water has been carried to the reservoir constructed in the other catchment basion. We always have intaken water from the river by this head work, even at the time of flood. To design such structure, we have to know the rerationship between the gate opening and the discharge of water or the discharge coefficient which varies widely according to the river water level. That orifice formula could be used in calculation to obtain the amount of discharged water from the gate has experimentally been confirmed by Toch, Honma and others. The discharge coefficient of the intake gate Cq is shown in its relationship to parameters expressing the gate geometry. Any agreement between actual gate discharge and Toch's experimental results could never be found when the gate geometry is different. Therefore, we can only obtain Cq value through a specific model study for a particular project. Specially in this intake mention should be made here to the fact that the loss of head Ф in the uniform flow sections upstreams and downstreams from the gate is ignored, and the value of Ф related to the Cq value. Relation between Cq and Ф can be obtained by the following equation using the Bernoulli's energay theorem, in which ψ. Ф are head loss parameters, Cq H1･H2 /√H12 (1+ψ) + H32 (Ф-l) and Cq value can be obtained by calculating head loss. On the other hand, if the systematic graphical representation of the relationship between the value q and the elements is obtained by the experimental measurements of hydraulic model tests, q-H1/h～H3/h, in which H1,H3 are the depths of flow in the upstream and downstream from the gates, should be considered applicable to the practical work and useful in checking up the experimental values with theoretical solution

Visualizing Individual Perceptual Differences Using Intuitive Word-Based Input

Numerous studies have investigated the fundamental dimensions of human tactile perceptual space using a wide range of materials. Participants generally touch materials and quantitatively evaluate variations in tactile sensations for pairs of adjectives pertaining to the material properties, such as smooth—rough and soft—hard. Thus, observers evaluate their perceptual experiences one by one in terms of adjective pairs. We previously proposed an alternative method of qualitative evaluation of tactile sensations. Our system can automatically estimate ratings of fundamental tactile properties from single sound-symbolic words. We were able to construct a word-based perceptual space by collecting words that express tactile sensations and applying them to the system. However, to explore individual differences in perceptual spaces, different databases for converting words into ratings of adjective pairs are required for each individual. To address this, in the present study we created an application that can automatically generate an individualized perceptual space by moving only a few words in the initial word-based perceptual space. In addition, we evaluated the efficacy of the application by comparing the tactile perceptual space before and after use

Identity-based Hierarchical Key-insulated Encryption without Random Oracles

Key-insulated encryption is one of the effective solutions to a key exposure problem. At Asiacrypt\u2705, Hanaoka et al. proposed an identity-based hierarchical key-insulated encryption (hierarchical IKE) scheme. Although their scheme is secure in the random oracle model, it has a ``hierarchical key-updating structure,\u27\u27 which is attractive functionality that enhances key exposure resistance. In this paper, we first propose the hierarchical IKE scheme without random oracles. Our hierarchical IKE scheme is secure under the symmetric external Diffie-Hellman (SXDH) assumption, which is known as the simple and static one. Particularly, in the non-hierarchical case, our construction is the first IKE scheme that achieves constant-size parameters including public parameters, secret keys, and ciphertexts. Furthermore, we also propose the first public-key-based key-insulated encryption (PK-KIE) in the hierarchical setting by using our technique

Identity-based encryption with hierarchical key-insulation in the standard model

A key exposure problem is unavoidable since it seems human error can never be eliminated completely, and key-insulated encryption is one of the cryptographic solutions to the problem. At Asiacrypt\u2705, Hanaoka et al. introduced hierarchical key-insulation functionality, which is attractive functionality that enhances key exposure resistance, and proposed an identity-based hierarchical key-insulated encryption (hierarchical IKE) scheme in the random oracle model. In this paper, we first propose the hierarchical IKE scheme in the standard model (i.e., without random oracles). Our hierarchical IKE scheme is secure under the symmetric external Diffie–Hellman (SXDH) assumption, which is a static assumption. Particularly, in the non-hierarchical case, our construction is the first IKE scheme that achieves constant-size parameters including public parameters, secret keys, and ciphertexts. Furthermore, we also propose the first public-key-based key-insulated encryption (PK-KIE) in the hierarchical setting by using our technique

Unconditionally Secure Revocable Storage: Tight Bounds, Optimal Construction, and Robustness

Data stored in cloud storage sometimes requires long-term security due to its sensitivity (e.g., genome data), and therefore, it also requires flexible access control for handling entities who can use the data. Broadcast encryption can partially provide such flexibility by specifying privileged receivers so that only they can decrypt a ciphertext. However, once privileged receivers are specified, they can be no longer dynamically added and/or removed. In this paper, we propose a new type of broadcast encryption which provides long-term security and appropriate access control, which we call unconditionally secure revocable-storage broadcast encryption (RS-BE). In RS-BE, privileged receivers of a ciphertext can be dynamically updated without revealing any information on the underlying plaintext. Specifically, we define a model and security of RS-BE, derive tight lower bounds on sizes of secret keys required for secure RS-BE, and propose a construction of RS-BE which meets all of these bounds. Our lower bounds can be applied to traditional broadcast encryption. Furthermore, to detect an improper update, we consider security against modification attacks to a ciphertext, and present a concrete construction secure against this type of attacks

Information-Theoretic Timed-Release Security: Key-Agreement, Encryption, and Authentication Codes

In this paper, we study timed-release cryptography with information-theoretic security. As fundamental cryptographic primitives with information-theoretic security, we can consider key-agreement, encryption, and authentication codes. Therefore, in this paper we deal with information-theoretic timed-release security for all those primitives. Specifically, we propose models and formalizations of security for information-theoretic timed-release key-agreement, encryption, and authentication codes; we also derive tight lower bounds on entities\u27 memory-sizes required for all those ones; and we show optimal constructions of all those ones. Furthermore, we investigate a relationship of mechanisms between information-theoretic timed-release key-agreement and information-theoretic key-insulated key-agreement. It turns out that there exists a simple algorithm which converts the former into the latter, and vice versa. In the sense, we conclude that these two mechanisms are essentially close

Acute myocardial infarction caused by an anomalous left main coronary artery in a 16-year-old boy

SummaryA variety of structural cardiovascular abnormalities have been implicated in deaths of athletes, particularly congenital coronary arteries of anomalous origin, which are rare but major causes of myocardial ischemia and sudden death in young people. We present here the case of a rare congenital coronary artery anomaly in a 16-year-old boy who suffered from acute myocardial infarction due to occlusion of the left main trunk coronary artery, providing specific intravascular ultrasound findings for this anomaly