oneSig

Problem Statement

OneSig turns scattered ERC20 balances across multiple EVM rollups into a single USDC position with one signature. It scans a user’s assets on every supported chain, builds a unified execution plan, and compiles all per chain approvals, swaps, and transfers into a merkle tree. Each leaf represents a chain specific action such as approving tokens or pushing them into a Uniswap pool for USDC settlement. The user signs only the root once through an EntryPoint 0.9 compatible flow. This produces a single multichain instruction that can be executed without switching networks or managing gas on multiple rollups. OneSig borrows the cross chain builder pattern from the Ethereum Interop Layer, but adapts it specifically for asset consolidation rather than general messaging. The result is a one tap exit into USDC that removes the friction of bridging, swapping, and coordinating actions across chains.

Solution

OneSig is built as an EIL inspired multichain builder that assembles ERC20 approvals, swaps, and transfers across several rollups into a single signed instruction. The frontend is written in TypeScript and React and collects ERC20 balances and allowances through direct JSON RPC queries. These actions are grouped into a merkle tree where each leaf contains the exact call data for a specific chain including approvals and the swap path into USDC on Uniswap. The user signs only the root using an EntryPoint 0.9 compatible account module, which lets the system derive and execute all leaf transactions without extra signatures. During development we explored EIL’s voucher and cross chain paymaster designs, but those models are optimized for generalized cross chain liquidity rather than simple asset consolidation, so we built a separate flow tailored for ERC20 unwinding. Several pieces are intentionally hacky, including simplified routing logic, manual calldata construction for Uniswap swaps, and a lightweight execution simulator that allowed the multichain flow to function consistently across chains during the hackathon timeframe.