Union: A Trust-minimized Bridge for Rootstock
Ramon Amela (1), Shreemoy Mishra (1), Sergio Demian Lerner (1, 2), and Javier \'Alvarez Cid-Fuentes (1) ((1) RootstockLabs, (2) Fairgate Labs)

TL;DR
Union is a secure, trust-minimized bridge protocol enabling Bitcoin transfer between Bitcoin and secondary blockchains, employing multi-party cryptography and innovative architecture to enhance security and efficiency.
Contribution
It introduces a novel multi-party bridge protocol with a packet-based architecture, enablers, and flexible light client framework, reducing trust assumptions and improving scalability.
Findings
Secure transfer of BTC between Bitcoin and other blockchains demonstrated.
The protocol operates securely under a 1-of-n honest participant assumption.
Enhanced capital efficiency and scalability through innovative design features.
Abstract
We present Union, a trust-minimized bridge protocol that enables secure transfer of BTC between Bitcoin and a secondary blockchain. The growing ecosystem of blockchain systems built around Bitcoin has created a pressing need for secure and efficient bridges to transfer BTC between networks while preserving Bitcoin's security guarantees. Union employs a multi-party variant of BitVMX, an optimistic proving system on Bitcoin, to create a bridge that operates securely under the assumption that at least one participant remains honest. This 1-of-n honest approach is strikingly different from the conventional honest-majority assumption adopted by practically all federated systems. The protocol introduces several innovations: a packet-based architecture that allows security bonds to be reused for multiple bridge operations, improving capital efficiency; a system of enablers to manage…
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Taxonomy
TopicsPlant Physiology and Cultivation Studies · Nematode management and characterization studies · Plant Reproductive Biology
