Scaling Blockchain Primitive
ZK Rollups
Layer 2 scaling using zero-knowledge proofs for instant finality
What are ZK Rollups?
ZK Rollups are Layer 2 scaling solutions that use zero-knowledge proofs to validate transactions. Instead of assuming validity like optimistic rollups, they cryptographically prove correctness for instant finality.
How They Work
Transaction Flow
- Users submit transactions to ZK rollup
- Transactions are executed off-chain
- Prover generates validity proof (SNARK/STARK)
- Proof and state root posted to L1
- L1 contract verifies proof
- State is finalized immediately
Zero-Knowledge Proofs
Proofs verify computation without revealing inputs:
- SNARKs: Smaller proofs, require trusted setup
- STARKs: Larger proofs, no trusted setup needed
Advantages
- Fast Finality: No challenge period needed
- Security: Cryptographic guarantees
- Privacy Potential: Can hide transaction details
- Lower Data Costs: Only proofs needed on L1
Disadvantages
- Complexity: Harder to implement
- EVM Compatibility: Challenging (improving)
- Prover Costs: Generating proofs is expensive
- Limited Opcodes: Not all operations supported
Types of ZK Proofs
| Type | Proof Size | Verify Time | Setup |
|---|---|---|---|
| Groth16 | ~200 bytes | ~10ms | Trusted |
| PLONK | ~400 bytes | ~20ms | Universal |
| STARK | ~50KB | ~50ms | None |
Major Implementations
- zkSync Era: General-purpose zkEVM
- Polygon zkEVM: EVM equivalent
- Starknet: STARK-based, Cairo language
- Scroll: bytecode-level compatible zkEVM
- Linea: Consensys zkEVM
Future Potential
ZK technology enables:
- Private transactions
- Cross-chain bridges
- Verifiable computation
- Identity solutions