Stellar now supports zero‑knowledge proof verification directly inside its smart contracts, giving developers new tools for privacy and heavy off‑chain computation. The upgrade uses Groth16 zk‑SNARKs and new BN254 cryptography, enabling apps to verify complex proofs in a single on-chain transaction.
How ZK Proofs Now Work on Stellar
With the recent X‑Ray protocol upgrade and new BN254 host functions, Soroban smart contracts can perform key elliptic curve and pairing operations needed for zk‑SNARKs. These functions mirror Ethereum’s EIP‑196 and EIP‑197 precompiles, which makes it easier to port existing ZK projects to Stellar.
The network currently supports verification of proofs produced by RISC Zero’s zkVM and circuits compiled with tools like Circom, using the Groth16 proving system. Developers generate proofs off‑chain and submit compact proof data to Soroban contracts, which verify them on-chain without re‑running the original computation.
RISC Zero Integration and Off-Chain Compute
Stellar’s new integration with RISC Zero lets developers prove that arbitrary code ran correctly in a zkVM and then verify that proof onchain. Nethermind built the verifier contract that connects RISC Zero proofs to Soroban, enabling apps to treat the zkVM as a verifiable black box.
This design shifts heavy work off‑chain: apps can process megabytes of data or complex logic elsewhere, then post only a cryptographic proof to Stellar. The contract processes the proof in a single transaction, keeping fees low and avoiding on-chain compute limits.
Stellar engineers have already released an open‑source “private payments” prototype that uses Groth16 proofs to hide deposit, transfer, and withdrawal details while keeping balances valid. The architecture combines a pool contract, a Groth16 Circom verifier, and membership Merkle trees to govern who can send and receive funds.
The foundation says these tools unlock new use cases, including confidential payroll, private remittances, and compliance‑friendly privacy pools for financial institutions. More broadly, any application that needs to prove facts about a user or transaction without revealing full data can now do that on Stellar.
For developers, native ZK verification on Soroban enables them to bring Ethereum‑style rollups, intent systems, and privacy protocols to a lower‑fee chain. Teams can reuse existing BN254‑based circuits and libraries instead of rebuilding their stacks on a different curve.
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