Mobility-as-a-Service (MaaS) is an advanced Intelligent Transport System (ITS) that integrates various modes of transportation to meet the demands of travellers. The system relies on frequent communication for data exchange between the MaaS provider and transport service providers. Ideally, such communication would utilize trust technologies between these entities. However, current MaaS systems lack transparency and reliability, and their centralized nature creates a single point of failure for the entire service. To address these issues, this paper proposes a blockchain-based MaaS, which includes an architecture and smart contract functionalities. The solutions are built on permissioned and permissionless Hyperledger Fabric and Ethereum blockchain platforms, respectively, for a realistic deployment of network architecture and proposed smart contracts. Additionally, the paper presents a framework derived from comparing these two blockchain platforms. Finally, the framework is evaluated, and open questions and challenges are analyzed.

Abstract Indifferentiability of iterated hash functions is seen as evidence that there are no structural flaws in the iteration structure of the algorithm. However, it is often overlooked that such considerations only hold in the random oracle model and do not give any guarantee in the standard model. In this article, we show the following separation result: there is a hash function that is indifferentiable from a random oracle, but is totally insecure in the standard model. In particular, we show that it does not satisfy collision or multicollision‐resistance, second preimage‐resistance or preimage‐resistance for any family of compression functions. Therefore, at least in theory, hash function indifferentiability does not guarantee the structural integrity of the hash algorithm in the standard model. Results in the random oracle model are not affected.

In this paper, we present a vision for a blockchain-based Mobility-as-a-Service (MaaS) as an application of edge computing. In current MaaS systems, a central MaaS operator plays a crucial role serving an intermediate layer which manages and controls the connections between transportation providers and passengers with several other features. Since the willingness of public and private transportation providers to connect to this layer is essential in the current realization of MaaS, in our vision, to eliminate this layer, a novel blockchain-based MaaS is proposed. The solution also improves trust and transparency for all stakeholders as well as eliminates the need to make commercial agreements with separate MaaS agents. From a technical perspective, the power of computing and resources are distributed to different transportation providers at the edge of the network providing trust in a decentralised way. The blockchain-based MaaS has the potential to emerge as the main component for a smart city transportation offering efficiency and reducing carbon dioxide emissions.

A distributed storage system (DSS) is a fundamental building block in many distributed applications. It applies linear network coding to achieve an optimal tradeoff between storage and repair bandwidth when node failures occur. Additively homomorphic encryption is compatible with linear network coding. The homomorphic property ensures that a linear combination of ciphertext messages decrypts to the same linear combination of the corresponding plaintext messages. In this paper, we construct a linearly homomorphic symmetric encryption scheme that is designed for a DSS. Our proposal provides simultaneous encryption and error correction by applying linear error correcting codes. We show its IND-CPA security for a limited number of messages based on binary Goppa codes and the following assumption: when dividing a scrambled generator matrix G^ into two parts G1^ and G2^ , it is infeasible to distinguish G2^ from random and to find a statistical connection between G1^ and G2^ . Our infeasibility assumptions are closely related to those underlying the McEliece public key cryptosystem but are considerably weaker. We believe that the proposed problem has independent cryptographic interest.

We develop and evaluate a data hiding method that enables smartphones to encrypt and embed sensitive information into carrier streams of sensor data. Our evaluation considers multiple handsets and a variety of data types, and we demonstrate that our method has a computational cost that allows real-time data hiding on smartphones with negligible distortion of the carrier stream. These characteristics make it suitable for smartphone applications involving privacy-sensitive data such as medical monitoring systems and digital forensics tools.

One of the most important aspects of a wireless health monitoring system is the security of data. In this paper, security attacks against the complete transmission chain of a medical health monitoring system are enumerated and classified based on their threat to three security principles: confidentiality, integrity and availability. The communication chain is divided in a standard way into three tiers and relevant threats are identified for each tier. Security requirements corresponding to these threats are presented. It is noted that end-to-end security is not feasible due to distributed computing and the incompatibility of the data standards of different tiers.