Zair

Zair offers privacy-preserving tools for Zcash airdrops by allowing users to prove they own eligible notes on Zcash while preserving the privacy of the notes owned and the amounts claimed.

Link to Documentation

This project has not been audited.

How it works

An organizer publishes a snapshot of the Zcash chain at a given height. Claimants scan for their eligible notes, then generate a ZK proof per note that demonstrates note ownership and unspentness without revealing the Zcash nullifier. Each proof instead exposes a domain-separated airdrop nullifier for double-claim prevention and is signed with a spend-authorizing key bound to a target-chain message. Verifiers then check the proofs against the snapshot and de-duplicate by airdrop nullifier.

See the Introduction for more details.

Crates

Crate	Description
zair-cli	Primary zair CLI binary tool
zair-sdk	The SDK and entrypoint for zair airdrops, used by the CLI
zair-core	Core crate with shared types, config and schemas
zair-nonmembership	Non-membership Merkle-tree primitive
zair-scan	Lightwalletd gRPC client and chain scanning
zair-sapling-proofs	Sapling proving and verification
zair-sapling-circuit	Sapling claim circuit (Bellman/Groth16)
zair-orchard-proofs	Orchard proving and verification
zair-orchard-circuit	Orchard claim circuit (Halo2)

Getting started

See Getting Started for build instructions and setup. The quickest path is using Nix:

nix develop
cargo build --release

Usage

Below is a minimal example workflow. See the CLI Reference for details or check zair --help for command options.

1. Derive keys

Extract the seed from your wallet mnemonic:

zair key derive-seed --mnemonic-file mnemonic.txt --no-passphrase

2. Generate parameters

Generate the trusted Sapling setup (required once):

zair setup sapling

3. Build configuration

Build the airdrop snapshot against a chain height:

zair config build --network testnet --height <SNAPSHOT_HEIGHT>

4. Claim

Run the full claim pipeline (prepare, prove, sign) in one step:

zair claim run \
  --config config.json \
  --seed seed.txt \
  --birthday <WALLET_BIRTHDAY> \
  --message claim-message.bin

5. Verify

Verify the submission (proofs and signatures):

zair verify run \
  --config config.json \
  --message claim-message.bin

License

Released under the MIT License.