Hazync achieves 27ms Bitcoin block verification with zero-knowledge proofs
In brief
- Hazync verified Bitcoin's first 1,789 blocks in 27 milliseconds using RISC Zero's zero-knowledge virtual machine
- Full historical backfill would require approximately 17 GPU-years; ongoing validation needs six Nvidia L40S GPUs
- Zero-knowledge proofs enable reusable, cryptographically verifiable Bitcoin validation without intermediary trust
Verification speed versus compute cost
Hazync's developer reports that a 1.7 MB standalone verifier checked a 226,434-byte cryptographic receipt covering the first 1,789 blocks of Bitcoin in 27 milliseconds. That's the upside. The downside: the developer estimates roughly 17 GPU-years for the historical backfill, followed by capacity equivalent to about six Nvidia L40S GPUs to keep pace with new blocks.
The speed matters because it means a light client or archive node can verify Bitcoin's history without running the full protocol stack. But the cost reveals why a complete genesis-to-tip proof campaign remains unfinished. The August 15 disclosure covers only Bitcoin's early blocks — a proof-of-concept, not production infrastructure.
How Hazync builds proofs
Hazync runs Bitcoin's rules inside the zkVM, proves that those rules accepted each covered block, and recursively folds block proofs into a single receipt. The public repository shows that the guest program was built from substantial parts of Bitcoin Core v28's consensus code and libsecp256k1.
To measure real-world cost, the developer benchmarked block 741,000. That block contained 670 inputs and required 394 UTXO leaves to validate. Proving it as 16 chunks across two L40S GPUs took about 55 minutes, including 27 minutes for aggregation — a reminder that millisecond verification is fast, but generating the proof is not.
Every receipt commits to a METHOD_ID, a fingerprint of the compiled guest program. This ensures that anyone holding a Hazync proof can verify it was generated from a specific, auditable version of the Bitcoin rules. Archive operators still supply transaction availability and retain historic witness and signature bytes, and best-chain selection stays with Bitcoin's most-work rule.
The project restarted its genesis board on August 4 after an internal audit forced a new baseline — a signal that the team is iterating on correctness before attempting the full chain.
