A Generic Framework for Cross-Chain Atomic Swaps of Digital Tokens

Decentralisation is one of the most important structural principles of blockchains and it should be present in all aspects of these systems. There is a growing scientific effort to develop protocols that enable the exchange of digital assets between two heterogeneous blockchains without a third-party arbitrator. We investigate the scenario where two parties wish to exchange digital tokens and run a swap protocol without the intervention of a third party. This is a complex and cooperative process for which - in a trust-less environment - atomicity and fairness must be ensured. While smart contracts provide a convenient way to achieve this, we want to ensure that the two parties leave no traceable data on the respective chains. The challenge here is that the two digital assets can reside on different chains with different signature schemes. Tackling these issues, we present a protocol description for the exchange of two arbitrary cryptocurrencies. A generic standard for atomic swap implementations in terms of the required cryptographic primitives is given. Additionally, we derive a protocol for the necessary interactions between two arbitrary chains using these primitives. To demonstrate applicability, we illustrate how this protocol can be instantiated with Schnorr and BLS signatures. © 2025 Elsevier B.V., All rights reserved.