220 research outputs found
OpenDSU: Digital Sovereignty in PharmaLedger
Distributed ledger networks, chiefly those based on blockchain technologies,
currently are heralding a next generation of computer systems that aims to suit
modern users' demands. Over the recent years, several technologies for
blockchains, off-chaining strategies, as well as decentralised and respectively
self-sovereign identity systems have shot up so fast that standardisation of
the protocols is lagging behind, severely hampering the interoperability of
different approaches. Moreover, most of the currently available solutions for
distributed ledgers focus on either home users or enterprise use case
scenarios, failing to provide integrative solutions addressing the needs of
both.
Herein we introduce the OpenDSU platform that allows to interoperate generic
blockchain technologies, organised - and possibly cascaded in a hierarchical
fashion - in domains. To achieve this flexibility, we seamlessly integrated a
set of well conceived OpenDSU components to orchestrate off-chain data with
granularly resolved and cryptographically secure access levels that are nested
with sovereign identities across the different domains.
Employing our platform to PharmaLedger, an inter-European network for the
standardisation of data handling in the pharmaceutical industry and in
healthcare, we demonstrate that OpenDSU can cope with generic demands of
heterogeneous use cases in both, performance and handling substantially
different business policies. Importantly, whereas available solutions commonly
require a pre-defined and fixed set of components, no such vendor lock-in
restrictions on the blockchain technology or identity system exist in OpenDSU,
making systems built on it flexibly adaptable to new standards evolving in the
future.Comment: 18 pages, 8 figure
Scalable and Privacy-preserving Design of On/Off-chain Smart Contracts
The rise of smart contract systems such as Ethereum has resulted in a
proliferation of blockchain-based decentralized applications including
applications that store and manage a wide range of data. Current smart
contracts are designed to be executed solely by miners and are revealed
entirely on-chain, resulting in reduced scalability and privacy. In this paper,
we discuss that scalability and privacy of smart contracts can be enhanced by
splitting a given contract into an off-chain contract and an on-chain contract.
Specifically, functions of the contract that involve high-cost computation or
sensitive information can be split and included as the off-chain contract, that
is signed and executed by only the interested participants. The proposed
approach allows the participants to reach unanimous agreement off-chain when
all of them are honest, allowing computing resources of miners to be saved and
content of the off-chain contract to be hidden from the public. In case of a
dispute caused by any dishonest participants, a signed copy of the off-chain
contract can be revealed so that a verified instance can be created to make
miners enforce the true execution result. Thus, honest participants have the
ability to redress and penalize any fraudulent or dishonest behavior, which
incentivizes all participants to honestly follow the agreed off-chain contract.
We discuss techniques for splitting a contract into a pair of on/off-chain
contracts and propose a mechanism to address the challenges of handling
dishonest participants in the system. Our implementation and evaluation of the
proposed approach using an example smart contract demonstrate the effectiveness
of the proposed approach in Ethereum
Non-Disclosing Credential On-chaining for Blockchain-based Decentralized Applications
Many service systems rely on verifiable identity-related information of their
users. Manipulation and unwanted exposure of this privacy-relevant information,
however, must at the same time be prevented and avoided. Peer-to-peer
blockchain-based decentralization with a smart contract-based execution model
and verifiable off-chain computations leveraging zero-knowledge proofs promise
to provide the basis for next-generation, non-disclosing credential management
solutions. In this paper, we propose a novel credential on-chaining system that
ensures blockchain-based transparency while preserving pseudonymity. We present
a general model compliant to the W3C verifiable credential recommendation and
demonstrate how it can be applied to solve existing problems that require
computational identity-related attribute verification. Our zkSNARKs-based
reference implementation and evaluation show that, compared to related
approaches based on, e.g., CL-signatures, our approach provides significant
performance advantages and more flexible proof mechanisms, underpinning our
vision of increasingly decentralized, transparent, and trustworthy service
systems
Scaling Private Collaborated Consortium Blockchains Using State Machine Replication Over Random Graphs
Blockchain technology has redefined the way the software industry\u27s core mechanisms operate. With recent generations of improvement observed in blockchain, the industry is surging ahead towards replacing the existing computing paradigms with consortium blockchain-enabled solutions. For this, there is much research observed which aims to make blockchain technology’s performance at par with existing systems. Most of the research involves the optimization of the consensus algorithms that govern the system. One of the major aspects of upcoming iterations in blockchain technology is making individual consortium blockchains collaborate with other consortium blockchains to validate operations on a common set of data shared among the systems. The traditional approach involves requiring all the organizations to run the consensus and validate the change. This approach is computationally expensive and reduces the modularity of the system. Also, the optimized consensus algorithms have their specific requirements and assumptions which if extended to all the organizations leads to a cluttered system with high magnitudes of dependencies.This thesis proposes an architecture that leverages the use of state machine replication extended to all the nodes of different organizations with seamless updates over a random graph network without involving all the nodes participating in the consensus. This also enables organizations to run their respective consensus algorithms depending on their requirements. This approach guarantees the finality of consistent data updates with reduced computations with high magnitudes of scalability and flexibility
Verifying the Integrity of Hyperlinked Information Using Linked Data and Smart Contracts
We present an approach to verify off-chained information using Linked Data, Smart Contracts, and RDF graph hashes stored on a Distributed Ledger. We use the notion of a Linked Pedigree, i.e. a decentralised dataset for storing hyperlinked information, as modelling foundation. We evaluate our approach by comparing different ways to build the Smart Contract. We develop a cost model and show, based on our implementation, that for managing multiple Linked Pedigree instances, a single larger Smart Contract is superior to multiple smaller Smart Contracts for supply chains shorter than 50 participants
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