The distributed ledger technology (DLT) landscape comprises a wide range of independent networks with little to none built-in interoperability. To be applied in traditional enterprises, these DLT systems must also interact with legacy systems with no support for the processes of a DLT. An important topic in DLT research is, therefore, to establish standardised protocols for cross-network transfer and exchange of data and assets. Ideally, these protocols should be general-purpose so that they can be applied on top of many different types of ledger systems. One such protocol, supporting asset transfer, is the Secure Asset Transfer Protocol (SATP) in development by the Internet Engineering Task Force (IETF). The SATP Core protocol draft by Hargreaves et al. (2025) describes an interoperability protocol that can facilitate asset transfer between two DLT systems, as well as between a DLT system and a non-DLT system. In either case, SATP imposes no restrictions on the underlying system implementations. Building on this work, in this paper, we present an adaptation of SATP that facilitates cross-network asset exchanges. This asset exchange protocol, named the Secure Asset Exchange Protocol, inherits the key advantages of SATP but enables asset exchanges instead of asset transfers.

Online voting for independent elections is generally supported by trusted election providers. Typically these providers do not offer any way in which a voter can verify their vote, and hence the providers are trusted with ballot privacy and in ensuring correctness. Despite the desire to offer online voting for political elections, this lack of transparency and verifiability is often seen as a significant barrier to the large-scale adoption of online elections. Adding verifiability to an online election increases transparency and integrity, as well as allowing voters to verify that the vote they cast has been recorded correctly and included in the tally. However, replacing existing online systems with those that provide verifiable voting requires new algorithms and code to be deployed, and this presents a significant business risk to commercial election providers, as well as the societal risk for official elections selecting for public office. In this paper we present the first step in an incremental approach which minimises the business risk but demonstrates the advantages of verifiability, by developing an implementation of key elements of a Selene-based verifiability layer and adding it to an operational online voting system. Selene is a verifiable voting protocol that publishes votes in plaintext alongside a voter's tracker. These trackers enable voters to confirm that their votes have been captured correctly by the system, such that the election provider does not know which tracker has been allocated to which voter. This results in a system where even a “dishonest but cautious” election authority running the system cannot be sure of changing the result in an undetectable way, and hence gives stronger guarantees on the integrity of the election than were previously present. We explore the challenges presented by adding a verifiability layer to an operational system. The system was used in two initial trials conducted within real contested elections. We conclude by outlining the further steps in the road-map towards the deployment of a fully trustworthy online voting system.

Securely transferring tokenised assets between largely non-interoperable blockchain networks is a great challenge to take on. Implementations must coordinate transactions on multiple blockchain networks which have inherently different characteristics and functionality. Moreover, implementations must coordinate transactions in strict order, in an atomic, synchronised way so that owners do not risk their assets becoming lost, while also mitigating the age-old problem of “avoiding double spend”. Several protocols for cross-network asset transfer, i.e. the bridging of assets, exist, and several production bridge implementations exist. However, frequent high-profile security breaches have arguably given bridges a bad reputation. Therefore, there is a clear need for standardised bridge protocols to re-establish trust. One initiative for standardising cross-network bridges is the Secure Asset Transfer Protocol (SATP) developed by the Internet Engineering Task Force (IETF). This protocol establishes four distinctive phases for the asset transfer process, driven by a standardised messaging cycle between specialised bridge orchestration applications, known as gateways. In this paper, we demonstrate a reference framework with functions needed to implement SATP. We describe our implementation of this reference framework, why SATP is unique and why SATP is likely to be an important contribution to powering future bridges.

Entrepreneurs, enterprises, and governments are using distributed ledger technology (DLT) as a component of complex information systems, and therefore interoperability capabilities are required. Interoperating DLTs enable network effects and synergies, and similarly to the rise of the Internet, it unlocks the full potential of the technology. However, due to the novelty of the area, interoperability mechanisms (IMs) are still not well understood, as interoperability is studied in silos. Consequently, choosing the proper IM for a use case is challenging. Our article has three contributions: first, we systematically study the research area of DLT interoperability by dissecting and analyzing previous work. We study the logical separation of interoperability layers, how a DLT can connect to others (connection mode), the object of interoperation (interoperation mode), and propose a new categorization for IMs. Second, we propose the first interoperability assessment for DLTs that systematically evaluates the interoperability degree of an IM. This framework allows comparing the potentiality, compatibility, and performance among solutions. Finally, we propose two decision models to assist in choosing an IM, considering different requirements. The first decision model assists in choosing the infrastructure of an IM, while the second decision model assists in choosing its functionality.

This paper discusses an approach for incremental change to an online voting system, introducing a verifiability layer based on the Selene protocol to a trusted-third-party-based system, resulting in a fully verifiable and transparent e-voting system. The paper also describes how to use Distributed Ledger Technology as a component of the implementation of Selene to manage the verifiability data in a distributed way for resilience and trust.

Within characteristic function games, agents have the option of joining one of many different coalitions, based on the utility value of each candidate coalition. However, determining this utility value can be computationally complex since the number of coalitions increases exponentially with the number of agents available. Various approaches have been proposed that mediate this problem by distributing the computational load so that each agent calculates only a subset of coalition values. However, current approaches are either highly inefficient due to redundant calculations, or make the benevolence assumption (i.e. are not suitable for adversarial environments). We introduce DCG, a novel algorithm that distributes the calculations of coalition utility values across a community of agents, such that: (i) no inter-agent communication is required; (ii) the coalition value calculations are (approximately) equally partitioned into shares, one for each agent; (iii) the utility value is calculated only once for each coalition, thus redundant calculations are eliminated; (iv) there is an equal number of operations for agents with equal sized shares; and (v) an agent is only allocated those coalitions in which it is a potential member. The DCG algorithm is presented and illustrated by means of an example. We formally prove that our approach allocates all of the coalitions to the agents, and that each coalition is assigned once and only once.

Since the seminal work of Dung, Argumentation Frameworks have been shown to find solutions to n-person cooperative games. In multi-agent systems, decentralised methods for multi-agent system coalition structure generation have been proposed. This paper offers the first dialogue game that utilises argumentation frameworks to find a coalition structure and a payoff vector in a decentralised manner. The payoff vector found is in the core set of stable solutions if the core is non-empty. This dialogue game also puts restrictions on the payoff vectors that can be proposed so that the most unfair ones are discarded. Lastly an algorithm is described that allows the agents to find out if the core is empty.