Burn-and-Mint vs Lock-and-Mint Bridges

Token bridges have two dominant designs. Understanding them changes how you assess bridge risk.

Lock-and-mint

User locks 100 USDC on chain A. Bridge mints 100 wrapped-USDC on chain B. To go back, user burns wrapped-USDC on B, unlocks USDC on A.

• Risk: the locked pot on chain A holds every user's collateral. Compromise the pot, drain everyone.
• Historical damage: Wormhole $325M (2022), Ronin $625M (2022), Multichain $126M (2023). All lock-and-mint or lock-and-attest.

Burn-and-mint (canonical)

User burns 100 USDC on chain A. Bridge mints 100 fresh USDC on chain B via authority delegated by the token issuer.

• Circle CCTP. Circle's native cross-chain USDC. Burn on A, mint on B. No locked pot. USDC on every supported chain is the real thing.
• NTT (Wormhole's Native Token Transfers). Same pattern for arbitrary tokens: burn on source, mint on destination via canonical authority.

Why burn-and-mint won

• No locked pot to steal.
• Bridged token = canonical token. No wrapped versions accumulating.
• Faster liquidity (mint is instant once burn is verified).

When lock-and-mint is still used

• Tokens with no bridge-enabled issuer (many older tokens).
• Non-canonical bridging (e.g. wBTC on Ethereum was lock-and-mint originally; still is via BitGo).

User rule

For USDC, ETH, and popular tokens, use canonical / burn-and-mint bridges (CCTP for USDC, native canonical bridges for L2s). For long-tail tokens where you have no choice, understand the lock-and-mint pot's size and audit history.