OXO Protocol
Bitcoin's DeFi Layer

Abstract

Bitcoin holds over $1 trillion in value yet participates in almost none of the decentralized finance ecosystem. The dominant narrative — "digital gold" — has kept BTC inert while every other major asset has found productive use on-chain.

OXO Protocol is a Layer-1.5 infrastructure built on Ethereum that bridges Bitcoin into a complete DeFi and payments ecosystem. Users deposit BTC and receive oxoBTC, a 1:1 backed on-chain representation that can be swapped, lent, staked, used across chains, or spent via NFC-enabled apps — all while remaining redeemable for real BTC at any time through the OXO bridge.

The protocol is live on Sepolia testnet with all core modules deployed and auditable. Mainnet launch is targeted for Q4 2026 following a community audit contest.

The Bitcoin Problem

2.1 — Digital Gold, Frozen in Place

Bitcoin was designed to be peer-to-peer electronic cash. In practice, the vast majority of BTC sits idle in wallets — appreciated in value but generating no yield, participating in no protocol, and spending no fees back into any ecosystem. The Lightning Network addressed micropayments but did not solve DeFi participation.

2.2 — Existing Solutions Fall Short

2.3 — The Missing Layer

Ethereum has its DeFi layer. Solana has its DeFi layer. Bitcoin — the largest crypto asset by market cap — has no native, fully integrated DeFi and payments layer. OXO is built to be exactly that.

The OXO Solution

3.1 — The Ecosystem Loop

Once a user bridges BTC into OXO Protocol, they enter a self-contained financial ecosystem. They can stay entirely within OXO, move to other EVM chains via cross-chain bridges, and always return to BTC through the OXO exit bridge. The protocol is designed so that OXO is always the entry and exit point for Bitcoin liquidity.

3.2 — Key Design Principles

Non-custodial by design. Users hold oxoBTC directly. The bridge custodial layer is secured by a 3-of-5 multisig in Phase 1, transitioning to Threshold Signature Scheme (TSS) in Phase 2.

OXO as the exit gate. Cross-chain transfers of oxoBTC are supported, but conversion back to real BTC is always performed through the OXO bridge. This creates durable protocol demand regardless of where users take their oxoBTC.

Yield on Bitcoin. By depositing oxoBTC into the staking contract, users earn OXO emissions and protocol fee revenue — generating yield on an otherwise idle asset.

Protocol Architecture

4.1 — oxoBTC Token

oxoBTC is an ERC-20 token with 8 decimal places (matching Bitcoin's satoshi precision). Every unit of oxoBTC in circulation is backed 1:1 by BTC held in the bridge custody. The token is minted exclusively by BridgeV3 upon verified deposit and burned upon redemption.

4.2 — BridgeV3

The bridge operates as a relayer-signed mint system. When a user sends BTC to the protocol deposit address, an off-chain relayer detects the confirmed transaction, signs a mint digest using ECDSA, and submits it to the mintAndTransfer() function. Replay attacks are prevented via unique deposit IDs stored on-chain.

A 0.1% bridge fee is charged on every mint and routed to the Protocol Treasury, which distributes it to stakers (70%), POL (20%), reserve (5%), and OXO buyback-burn (5%).

OXO fee discount: Users staking ≥1,000 OXO pay zero bridge fees.

4.3 — ZK Rollup

The OXO ZK Rollup is a Groth16-based validity rollup built with Circom circuits. Phase 1 supports 256 transactions per batch with 8-account state management. The sequencer aggregates transactions off-chain, generates a zero-knowledge proof, and submits the state root to OXORollup.sol on Ethereum for verification.

Intentional scope: The Phase 1 circuit is deliberately minimal — a production-proven foundation that is upgradeable. The Circom circuit, trusted setup, and on-chain verifier are all replaceable without migrating user funds. Increasing batch size from 256 to 1,024+ transactions requires only a circuit recompile and a new trusted setup ceremony, not a protocol migration. All 11 contracts are deployed and verifiable on Sepolia Etherscan.

Core Modules

5.1 — Protocol Fee Flow

Tokenomics

6.1 — Token Overview

6.2 — OXO Distribution

6.3 — OXO Utility

6.4 — Emission Schedule

Staking rewards are emitted at 0.1 OXO/second (8,640 OXO/day) from the Staking contract's OXO reward pool. The emission rate is adjustable by the admin and will transition to DAO governance. At current rate, the 17.5M reward allocation lasts approximately 5.5 years.

6.5 — Deflationary Mechanism

5% of all protocol fee revenue collected by the Treasury is used for OXO buyback and burn. The purchased OXO is sent to the dead address (0x000...dEaD), permanently removing it from circulation. This creates a deflationary counterforce to staking emissions. Total burned OXO is tracked on-chain via the totalOxoBurned variable.

Security Model

7.1 — Bridge Custody

Phase 1 (current): 3-of-5 multisig relayer. Five independent key holders must co-sign any mint operation. No single point of failure.

Phase 2 (roadmap): Transition to Threshold Signature Scheme (TSS) — a cryptographic protocol where the private key is never assembled in one place. This eliminates custodial risk while maintaining operational speed.

7.2 — Smart Contract Security

All core contracts use OpenZeppelin v5 audited libraries. Specific protections include:

7.3 — Liquidity Bootstrapping Plan

A decentralized exchange only functions with sufficient liquidity. OXO Protocol addresses the cold-start problem through a phased, protocol-owned liquidity (POL) strategy rather than relying solely on external LPs.

Protocol-owned liquidity is non-withdrawable by design — LP tokens from addPOL() are held permanently in the Treasury contract. This provides a price floor and guarantees that the DEX remains functional regardless of external LP behavior. Additional liquidity incentives (LP staking) are planned for the mainnet launch campaign.

7.4 — Audit Plan

Pre-mainnet, OXO Protocol will run a competitive audit contest on Code4rena with a minimum $15,000 reward pool. Community auditors have historically found critical issues in comparable protocols. All findings will be publicly disclosed and resolved before launch.

Roadmap

Deployed Contracts (Sepolia Testnet)