The 12th KIR: Auditable Privacy Preserving FT/NFT Transfer on Klaytn Blockchain


KLAY Funding

  • Proposed: KLAY worth USD 300,000


Brief Introduction of the Project

We have successfully developed Zklay which is a zero knowledge proof based Klay (and FT) transfer scheme to support privacy and auditability in Klaytn at the first KIR. From the lesson, we will propose KIPs for privacy, auditability, and zero-knowledge supporting. We improve the proof generation performance and reduce the gas consumption for Zklay. In addition we extend the proposed scheme to support NFT (non-fungible token).

In detail, we will propose a new KIP (auditable privacy preserving fungible token) to allow privacy and auditability similarly to KIP-7. Moreover, to reduce the gas cost in the current version of the proposed scheme, we will propose a new native instruction called “MiMC” hash in Klaytn as KIP. The MiMC hash has been proposed to accelerate the hash computation in zk-SNARKs proof generation since the SHA256 is too slow in zk-SNARKs proof generation. However, since it is not supported as a native instruction, its gas cost is too high compared with the existing SHA256 that is supported as a native instruction.

To improve the proof generation performance which determines the transaction generation performance in a user side, and the proof verification performance that affects the gas consumption in a smart contract, we devise a new faster and more efficient membership proof which is the major performance bottleneck in zk-SNARK based on RSA accumulator.

Finally, we will extend Zklay to support NFT with auditability and privacy, and define a new KIP (auditable privacy preserving non-fungible token) similar to KIP-17 (non-fungible token) and KIP-37 (multi token). For NFT Zklay, we will define the transaction format, the wallet interface with a wallet example, and so on. And we wil implement and show the NFT Zklay demo.

Key Deliverables

Four deliverables are included as below:

  1. Technical papers: research paper for fast membership proof. Zklay for NFT
  2. Zklay Dapps for FT and NFT with a fast membership proof
  3. Zklay smart contracts in Klaytn blockchain
  4. KIP proposals
  5. MiMC hash code for Klaytn core
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