FastPath - BTC Identity Link (v6)

BTC Identity Link v6.0.0 (Arbitrum)

SECURITY REQUIREMENT: Cold Storage Bitcoin Signature Only

Your Bitcoin identity acts as a stable, long-lived root proof. The original on-chain identity record is permanent; if relinking is enabled, the active EVM controller can be changed later while history remains preserved.

✅ SAFE - Hardware/Cold Wallets: Trezor, Ledger, ColdCard, BitBox (keys never leave device)

✅ SAFE - Software Wallets: Sparrow, Electrum (ONLY when connected to hardware)

⚠️ UNSAFE - Hot Wallets (DON'T USE): Mobile apps, browser extensions, desktop wallets with exposed keys

⚠️ MOBILE OPTION (HIGHER RISK): Zeus can sign messages, but treat as hot-wallet risk for long-lived identity links.

⚠️ These can sign, but for stable identity links we strongly recommend cold storage.

❌ IMPOSSIBLE - Exchange Wallets: Coinbase, Binance, etc. don't support message signing

Note: Your EVM wallet (MetaMask, Ledger, etc.) can be hot — only Bitcoin signature needs cold storage. You can relink to a new EVM address if needed.

Can this signature spend my Bitcoin?
No. This is a message signature only. It cannot move BTC, create a Bitcoin transaction, or give the app access to your private key.

What am I actually linking?
You are linking your Bitcoin identity to your connected EVM address. The Bitcoin key acts as the root proof; the EVM address becomes the active on-chain controller for Solidity actions.

Why is cold storage recommended?
Because this identity can become long-lived. Hardware or cold-storage signing keeps the root Bitcoin key isolated.

Why use derived wallets?
Derived wallets act as daily-spend operational wallets under one authorized identity. The main linked wallet stays stable for higher-trust contexts like DeFi, DAO membership, and long-term proof of control.

What does this make possible?
A Bitcoin signature anchors a stable root identity. An EVM authorization can then unlock readable .btc names, subdomains, daily-use wallets, and cross-chain endpoints without forcing users to reuse their real linked wallets everywhere.

Does linking expose my real wallet?
No private keys are exposed. The app only sees public identity data and the signature. The private Bitcoin key stays inside your wallet or signing device.

Can I change the active EVM controller later?
Yes, if relinking is enabled. Relinking requires a new EVM address and a fresh Bitcoin-authorized signature. The original identity history remains preserved.

What is the main risk?
The main risk is losing control of the Bitcoin key, losing control of the active EVM controller, or signing the wrong message. Always verify the exact message before signing: it should be the EVM address you intend to link.

Why does this matter for Solidity finality?
Once linked, Solidity contracts can treat the linked controller or derived EVM wallets as authorized identity endpoints. Derived wallets can act as daily-use endpoints for Solidity actions authorized by the root Bitcoin identity.

This page links your Bitcoin address to your connected EVM wallet, creating a stable on-chain identity.

Wallet

Not connected

Contract Address (FastPathIdentity)

Registration Form

1. Message to Sign (Your EVM Address)

Note: The contract requires the lowercase address. Ensure your Bitcoin wallet signs the exact string above.

2. Bitcoin Signature (Base64)

Paste signature from your wallet. For long-lived identity links, use cold-storage Bitcoin signing.

This signature cannot spend BTC. It only proves control of your Bitcoin identity and authorizes the selected EVM controller.

Registration Preview

Bitcoin Hash160:- Recovered Bitcoin Address:- Linked EVM Address:- Fee:- Network:-

Check Identity Link

Enter an EVM address, Bitcoin address, or Hash160 to verify its registration.

Search Input

Relink Bitcoin Identity

Transfer control of your Bitcoin identity to a new EVM address. Requires Bitcoin signature and cooldown period.

⚠️ Important: Relink Requirements

• Requires Bitcoin signature from your cold storage
• 3-day cooldown between operations
• Original mapping remains permanent (immutability preserved)

Current Bitcoin Hash160 New EVM Address (Controller) Bitcoin Signature

Sign the lowercase hex of your NEW EVM address with your Bitcoin private key. The public key will be auto-recovered from your signature.

Finalize Relink

After cooldown period expires, anyone can finalize the relink.

Bitcoin Hash160 to Finalize

Check Relink Status

Bitcoin Hash160

Early Adopter Rewards NFT

Link on Sepolia and claim a 10% discount NFT. Connect your wallet and check eligibility.

Early Adopter NFT

Permanent 10% discount on all FastPath protocol fees once you’re verified on Sepolia.
Connect wallet → Check eligibility

How it works:
1. Link your BTC address on Sepolia Testnet.
2. We verify your hash160 linkage against the contract.
3. If eligible, sign to claim your NFT on Sepolia.