Network and Distributed System Security Symposium 2025
The Network and Distributed System Security (NDSS) Symposium is a premier forum that promotes the exchange of information among researchers and practitioners in the field of network and distributed system security. This symposium emphasizes the practical aspects of security, particularly focusing on the design and implementation of actual systems. It provides a platform for discussing the latest research and developments in Internet security, making it a vital event for staying updated on cutting-edge advances in the field.
At NDSS 2025, held from 24 to 28 February 2025 in San Diego, California, Giulia Scaffino presented work titled “Alba: The Dawn of Scalable Bridges for Blockchains,” coauthored with Lukas Aumayr (TU Wien), Mahsa Bastankhah (Princeton University), Zeta Avarikioti (TU Wien), Matteo Maffei (TU Wien).
Over the past decade, the emergence of cryptocurrencies has significantly engaged both academic and industrial sectors, fostering a robust and varied blockchain ecosystem with innovative applications. A key development in this area has been the creation of blockchain “bridges.” These bridges are designed to improve interoperability between different blockchains, each with unique attributes, facilitating asset transfers crucial for maximizing the potential of Decentralized Finance (DeFi) systems. Despite their increasing popularity, existing trustless bridge protocols face challenges. Some, like light-client-based bridges, transmit too much information, while others, such as those using zero-knowledge proofs, require extensive computational resources. These inefficiencies often arise from the need to securely prove the inclusion of a transaction on one blockchain to another, a process that is sometimes redundant due to the capabilities of off-chain solutions like payment and state channels to handle transactions securely without on-chain publication. However, traditional bridges do not yet support the verification of these off-chain payments, highlighting a significant gap in current blockchain interoperability solutions.
Giulia’s presentation introduced the innovative concept of “Pay2Chain” bridges, which harness the benefits of off-chain solutions to circumvent the limitations of existing bridges. The proposed Pay2Chain bridge, named Alba, is designed to enable the efficient, secure, and trustless execution of conditional payments or smart contracts on a target blockchain, triggered by off-chain events. Alba not only offers technical benefits but also significantly enhances the ecosystem of the source blockchain by supporting DeFi applications, multi-asset payment channels, and optimistic stateful off-chain computation.
The team formalized the security of Alba against Byzantine adversaries within the Universal Composability (UC) framework and further enriched the analysis with game-theoretic insights. They also introduced formal scalability metrics to validate Alba’s efficiency. Empirical evaluations have confirmed that Alba’s communication complexity and on-chain costs are highly efficient, with its optimistic case incurring only twice the cost of a standard Ethereum transaction for token ownership transfer. This presentation underscored Alba’s potential to significantly advance blockchain interoperability and efficiency.
