✅ Master Cross-Chain Bridges
Understand lock-and-mint, architecture, and security models
Move assets between different blockchains
Your Progress
0 / 5 completed🎓 Module Summary
🌉 What You Learned
1. The Interoperability Problem
Blockchains are isolated—Ethereum can't see Polygon, Bitcoin can't access Solana. Cross-chain bridges solve this by creating synthetic connections, enabling asset portability across ecosystems. $100B+ flows through bridges daily.
2. Lock-and-Mint Mechanism
Classic bridging: lock assets on source chain (escrow), mint wrapped tokens 1:1 on destination. WETH on Polygon is backed by ETH locked on Ethereum. Reverse: burn wrapped, unlock original. Maintains peg via economic incentives.
3. Bridge Types and Trade-offs
Trusted (fast, centralized), Federated (balanced, most common), Optimistic (secure, 7-day delays), ZK (future, expensive now). Speed vs Security vs Decentralization—pick 2. Choose based on use case: speed for traders, security for large transfers.
4. Security is Critical
$2.5B+ stolen from bridges in 2022—more than all other DeFi hacks combined. Ronin ($625M), Poly Network ($611M), Wormhole ($325M) prove bridges are high-value targets. Attack vectors: validator compromise, smart contract bugs, oracle manipulation.
5. Production Architecture
7-step flow: user initiates → lock on source → relayers detect → validators sign → relay to destination → mint wrapped → user receives. Relayers provide liveness, validators provide security. Gas optimization via batching, ZK proofs, Merkle trees.
💡 Key Insights
- •Bridges are the "internet" of blockchains—enable interoperability but introduce trust assumptions not present in same-chain transactions.
- •Every major L2 (Arbitrum, Optimism, Polygon, zkSync) relies on bridges. Multi-chain is the future, bridges are unavoidable.
- •Security > Speed for large transfers. Use optimistic bridges or wait for ZK bridges to mature. Don't trust 3-of-5 multisigs with $1M+.
- •Wrapped tokens enable DeFi composability—wBTC on Ethereum powers Compound, Aave, Curve. Same concept as bridges use.
- •Relayers vs Validators: Relayers can't forge messages (no keys) but ensure liveness. Validators can't censor (anyone can relay) but control security.
🎯 Knowledge Check
Test your understanding of cross-chain bridges with this 5-question quiz. Each question includes detailed explanations.