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Bridges differ mainly in how they represent assets on the destination chain and who secures the transfer.

The main architectures are lock-and-mint, burn-and-mint, and liquidity pool bridges.

In lock-and-mint, the original asset is locked on the source chain and a wrapped version is minted on the destination.

The wrapped token is fully backed by the locked collateral in the bridge contract.

In burn-and-mint, the token is burned on the source chain and an equal amount is minted natively on the destination.

This requires the token contract on both chains to be controlled by the bridge, but avoids wrapped representations.

Liquidity pool bridges hold reserves of the same asset on both chains.

You deposit into the source pool and instantly withdraw from the destination pool — no minting, just a swap from existing liquidity for a fee.

Every bridge needs to verify the source event happened. Verification models include:

• External multisig/federation
• Optimistic with fraud proofs
• Light client / native verification
• ZK proofs

The simplest (and historically most exploited) model uses a multisig of signers who attest transfers.

Security equals the honesty of those signers — if enough keys are compromised, funds can be stolen.

Optimistic bridges assume a transfer is valid and allow a challenge window where watchers can dispute fraud.

This adds a delay but reduces reliance on a trusted signer set.

A light-client bridge verifies the source chain's block headers and proofs directly on the destination chain.

This is the most trust-minimized approach — security comes from the chains themselves, not external parties.

ZK bridges use validity proofs to attest that an event occurred on the source chain.

The destination verifies a succinct proof, combining strong security with efficient on-chain verification — an emerging frontier.

A canonical bridge is purpose-built for one chain pair (e.g. an L2's official bridge). A generalized bridge connects many chains through one protocol.

Generalized bridges are convenient but concentrate risk across all connected chains.

Bridge architectures combine an asset model (lock-mint, burn-mint, or liquidity pools) with a verification model (multisig, optimistic, light client, or ZK).

The verification model largely determines safety. Next we study why bridges get exploited.

You learned that:

• Asset models: lock-and-mint, burn-and-mint, liquidity pools
• Verification: multisig, optimistic, light client, ZK
• Light-client and ZK bridges are most trust-minimized
• Canonical vs generalized bridges trade convenience for concentrated risk

Next: bridge security risks.