TL;DR;

• Why are we building yet another bridging protocol? Read our thesis.
• Existing bridging protocols are NOT trustless; instead, they are built on third party relayer systems, making them dependent on complex and hardly traceable security mechanisms.
• Adding new networks to these systems can compromise the entire security of the protocol or integrator. This concern leads to the implementation of permissioned access and approval processes for new networks joining these systems.
• We challenge this approach by introducing PreHTLC, an improved version of HTLC that addresses practicality issues with atomic swaps like secret management and claim transactions on the destination chain.
• Atomic swaps are widely regarded as the most secure method of asset exchange.
• The proposed protocol is permissionless and has homogeneous security.
• The protocol supports multi-hop transactions, allowing bridging between chains that don't have direct liquidity provider connections.
• We demonstrate how new networks and integrators can connect to the protocol.
• We release the protocol’s spec and initial implementation for Bitcoin, EVM, Starknet, TON, Solana, and Sui/Aptos.
• Finally, we are launching the Pre-Alpha version to try out.

1. Introduction

As the cryptocurrency ecosystem rapidly expands, new chains—including Layer 1 (L1), Layer 2 (L2), side-chains, and app-chains—are continually emerging. While this proliferation enhances scalability and functionality, it also creates challenges in moving assets seamlessly across chains. Bridging protocols aim to solve this issue, but current solutions face significant scalability and trust limitations.

2. The Bridging Protocols

Bridging protocols are designed to connect isolated blockchain networks by facilitating asset transfers between them. Typically, they depend on third party relayer systems to transfer and validate information across chains. Once a transaction is confirmed on the source chain, the relayer sends this information to the destination chain to execute the value transfer.”

<aside> 💡 We use the term “third party relayer” to collectively describe various solutions, from optimistic Oracles (Across) to separate settlement chains with their own relayers (Wormhole) and so-called verification networks (Stargate—LayerZero).

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3. Limitations of Existing Bridging Approaches

Despite their widespread adoption, bridging protocols built on top of third party relayer systems introduce significant challenges:

• Permissioned Access: New networks must obtain approval from bridging protocols to be supported.
• Scalability Constraints: Adding a new network requires updating relayers across all existing networks, complicating any-to-any chain transactions.