Contributions published at Communication Systems Group (Burkhard Stiller)

null

null

Due to the growing interest in the blockchain (BC),several applications are being developed, taking advantage ofthe benefits that such technology promises to deliver, such asremoval of Trust Third Parties (TTP) to verify transactions anddata immutability. However, these applications require certainaspects, such as high transaction throughput or data privacy,that early BC implementations (e.g.,Bitcoin) did not provide.Thus, a myriad of novel BC implementations was developed,which introduced the issue of choosing the right implementationfor a specific use-case. This paper presents a framework, calledPleBeuS, to address this selection issue by allowing users tospecify policies that rule the automatic selection of the BC thatdata will be stored. The selection process relies on a cost-awareapproach and considers both public and private implementationsand their technical characteristics. Moreover,PleBeuScom-municates with a BC-agnostic interoperability API to enforcetransactions. The evaluation of thePleBeuSprototype showedthat it is possible to automatically select a BC-based on userpolicies, considering cost thresholds and technical details (e.g.,BC throughput, deployment), and reduce manual interaction.

In Industry 4.0 (I4), the Industrial Internet of Things (I2oT) data streams are prone to significant data manipulation risks. The integration of Blockchains (BC) with I2oT may become a solution preventing from this problem. This paper provides a blockchain-agnostic Blockchain I2oT (BI2oT) architecture called BIIT that allows developing a broad range of BC applications fully integrating Internet of Things (IoT). The mechanisms introduced in BIIT aim at solutions that provide data reliability, limit the computational overhead, and enhance energy efficiency. BIIT is evaluated through real-world experimentation.

The digitalization of democratic processes has attracted much attention in recent years. For example, spreading and signing a petition via the internet is now easier than ever. Likewise, electronic voting is of interest to many countries and organizations. Ongoing research in this area for over two decades shows that it is no simple task to transfer the analogous act of casting a ballot and vote-tallying to the digital realm. The opacity of digital systems requires ways of verifying that every valid vote is included in the vote counting and no manipulations happened. This property is called verifiability. At the same time, the system must ensure the voter's privacy. Although many countries have made the step to electronic voting (e.g., in the form of direct recording devices placed at polling stations), only in rare cases ballots can be cast remotely in so-called Remote Electronic Voting (REV) systems. Research has proposed several REV protocols offering varying levels of ballot privacy and verifiability, but practical implementations are few. Therefore, this thesis focuses on the design and implementation of a REV system based on a protocol with the specific property of unconditional privacy. This privacy notion does not depend on trust in a central authority nor the intractability of an underlying mathematical problem. To satisfy the protocol's minimal trust assumptions, our implementation applies blockchain as an enabler of transparent, tamper-proof, and decentralized platforms. In particular, we make use of Tendermint and Cosmos-SDK to construct an append-only bulletin board and design a voting system prototype around it that implements the protocol. The prototype highlights pitfalls and necessary considerations that only become clear through the transfer from theory to practice. It shows that, in combination with blockchain, the voting protocol's central issue becomes scalability, an issue to be overcome in future research.

null

null

null

null

Digitization of electoral processes depends on confident systems that produce verifiable evidence. The design and implementation of voting systems has been widely studied in prior research, bringing together expertise in many fields. Switzerland is organized in a federal, decentralized structure of independent governmental entities. Thus, its decentralized structure is a real-world example for implementing an electronic voting system, where trust is distributed among multiple authorities. This work outlines the design and implementation of a blockchain-based electronic voting system providing cast-as-intended verifiability. The generation of non-interactive zero-knowledge proofs of knowledge enables every voter to verify the encrypted vote, while maintaining the secrecy of the ballot. The Public Bulletin Board (PBB) is a crucial component of every electronic voting system, serving as a publicly verifiable log of communication and ballots - here a blockchain is used as the PBB. Also, the required cryptographic operations are in linear relation to the number of voters, making the outlined system fit for large-scale elections.

Blockchains (BCs) are back-linked chain of records termed as blocks. To establish decentralized trusted systems, BCs employ consensus mechanisms. During the past ten years, there have been various proposals of BC design and implementations. However, most of the developed sate of the art BCs suffer from scalability issues. In order to enhance the scalability of the BCs, this paper proposes a transaction aggregation mechanism on a Proof-of-Stake (PoS)-based BC. Having developed the transaction aggregation and double linked blocks, efficient prevention and control of the BC's size growth is observed in the evaluated scenarios.

Since the inception of the internet in 1992, more and more elements of our lives are getting intertwined with it, whether it be for commercial purposes, leisure or communication. The need to identify entities behind IP addresses led to the growth of a large identity and access management (IAM) system industry, which is likely to grow even further with the continuous expansion of the internet, and the creation of more digital products and services. History has shown that correctly deploying identity management (IdM) systems is an extremely dicult task and led to the formulation of several principles how identity can and should be managed. For more than twenty years, a signicant amount of research has been conducted as well as the industry has proposed and rened a range of dierent systems. Still, there is no widely accepted solution. Critical issues in the range of usability, access control, security and especially privacy are appearing. The emergence of blockchains and distributed ledgers attracted the attention of academic research and industry to potentially oer a new basis to build IdM systems upon. This master thesis evaluates the prospects of blockchain technology for IdM. Current approaches are reviewed and a prototype for the case of Switzerland is implemented to showcase the technology's advantages and potential drawbacks. While the majority of the numerous industry approaches and use cases focus on fullling the promise of self-sovereign identity (SSI), it has shown that a blockchain setting for IdM brings a lot of new challenges, especially regarding usability and privacy matters. As various projects and initiatives under the supervision of global consortia and standardization bodies are maturing to possibly enable the vision of SSI in the near future, there are also other perspectives on IdM beyond the end-users' problems. This thesis presents a prototype based on Hyperledger Fabric, improving security and veriability around the IdM of citizen registers and its integration with the Swiss remote postal voting process. It is shown that a number of previously identied issues in the paper-based voting process can be solved while also providing the basis for a more generally interoperable and trustworthy federalist government IT infrastructure.

null

null

Academic certificates have major relevance in the labor market, signaling capability, and the level of education and skills of the recipient. Unfortunately, recent years have seen an increase in fraud, ranging from inflating academic grades to fake diplomas. A counter- measure use-case applicable to academic certificates is Proof-of-Existence (PoE), which effectively timestamps a certificate, thus, proving the existence of exactly this certificate, without leaking information about its content (the certificate’s data). Prior work presented the initial requirements for a solution targeted at the University of Zurich [1], an essential building block of such a solution is identity and access management (IAM). The goal of this master’s thesis is to design and implement a suitable private distributed ledger (DL) solution with an integrated identity and access management module. The resulting solution is intended to be used in the Swiss Educhain service [2] to satisfy the main requirement of the various stakeholders, which is the issuance and verification of digital certificates utilizing blockchain technology. The Proof-of-Concept (PoC) implementation is evaluated against the identified requirements and the prototype’s functionality. This master’s thesis provides a blockchain-based identity and access management solution as an integral part of the produced Swiss Educhain PoC implementation.

Nowadays the cloud architecture is a growing trend that allow us to scale systems without having a physical architecture. This seems to be the future but it also presents several challenges for the current IT System Administrators since cyber attacks are on the growth and the need for performance and availability is also on the growth. In order to mitigate this problem we created a ChatBot using DialogFlow that gathers information from the System Administrator and maps the requirements using a pretrained Machine Learning model that use Natural Language Processing and Natural Language Understanding to identify and match possible requirements in a few layers of questions using the UNIX Man page collection as a database. The tool will also feature a client that will retrieve the data and process it using the described architecture to generate a data structure in JSON that other tools could use to generate a solution for the existing problem. Furthermore, we evaluated the solution using a loss function and a case study to check the impact and usability of the tool in real life.

The falsification of academic certificates is a major problem in today’s world, as they play an important signaling role in the labor market. With more and more diplomas being digitally issued, a public blockchain possesses ideal properties to combat fake diplomas, as it is tamper-proof, transparent and does not need centralized control. In this thesis, a digital diploma issuance and verification process using the Proof-of-Existence (PoE) mechanism is designed and implemented. The process is integrated within the Swiss Educhain Proof-of-Concept (PoC). After the integration, an evaluation of the implemented issuance and verification process is provided. The resulting PoC is able to provide notarization of extensible digital diplomas while abstracting the technical complexities behind a fron- tend.

L-SCN is a two-layered Service-Centric Networking (SCN) architecture. The L-SCN design splits the network into domains and specifies communication protocols for service provider information propagation. Nodes in a domain receive substantial knowledge about the available resources (e.g., CPU, RAM) and available services within the domain, while the communication between different domains is realized through supernodes. We extend L-SCN with new communication mechanisms, which improve the processing time and provide lower protocol overhead for service request processing. The two proposed mechanisms are named event-driven and provider-driven. The event-driven mechanism propagates service provider information based on an event (e.g., high overload). The provider-driven mechanism propagates service provider information periodically.

null