Lock-and-Mint Bridges
The oldest and most intuitive bridge design: lock a token on Chain A, mint a synthetic representation on Chain B. When you want to go back, burn the synthetic and unlock the original. Simple in concept — treacherous in execution. This page dissects the mechanism, the trust assumptions, and why billions have been lost when these systems fail.
🔄 Token Flow Animation
Watch tokens move through the lock-and-mint lifecycle. Click steps to advance manually or let it auto-play.
User sends native tokens to the bridge contract on the source chain.
📊 WBTC vs Portal (Wormhole) vs tBTC
Three lock-and-mint implementations, three wildly different trust models.
WBTC
- Custodian: BitGo (centralized)
- TVL: ~$5B+
- Trust: Single entity holds all BTC
- Minting: Merchant-gated (not permissionless)
- Audit: Proof-of-reserve on-chain
- Risk: BitGo compromise = total loss
Portal (Wormhole)
- Guardians: 19 validators (⅔ quorum)
- TVL: ~$1B+
- Trust: Multisig of known entities
- Minting: Permissionless
- Hack: $320M (Feb 2022) — signature bypass
- Risk: Guardian collusion or bug
tBTC v2
- Custodian: Decentralized signers (Threshold Network)
- Trust: Random signer selection + staking
- Minting: Permissionless
- Collateral: Staked T tokens as bond
- Risk: ⅓ signer collusion, smaller TVL
⚠️ Risk Simulator
How much value is at risk? Adjust parameters to model lock-and-mint failure scenarios.
🔥 Lock-and-Mint Exploits Timeline
Every major lock-and-mint bridge exploit, and what went wrong.
Attacker bypassed signature verification on Solana side, minting 120k wETH unbacked. Jump Trading covered the loss.
North Korea's Lazarus Group compromised 5 of 9 validators (4 Sky Mavis + 1 Axie DAO). Wasn't discovered for 6 days.
A botched upgrade made every message valid by default. Hundreds of copycat attackers drained the bridge in a "decentralized robbery."
CEO held all private keys. Chinese authorities arrested him; funds moved from MPC wallets. Project collapsed entirely.
⚖️ Maintaining the Peg
A wrapped token should always be worth exactly 1:1 with its backing asset. Here's what maintains — or breaks — that peg.
Hover over the chart to see peg deviation events.