Ztarknet 🛡️🐺 proposes a Starknet-style L2 that executes Cairo programs, proves the resulting state transitions with Circle STARKs (Stwo), and settles those transitions on Zcash L1 by having full nodes verify the proof natively via a TZE verifier. It reuses an existing Starknet client (e.g., Madara) for sequencing/execution and a Stwo/Cairo prover for proofs. The L1 verification surface is a single TZE type defined by a draft ZIP.

Why Zcash? Zcash already offers strong base-layer privacy. Ztarknet explores programmability and scale via an L2—with validity proofs checked natively on Zcash using the TZE framework (ZIP-222) and the associated digest changes (ZIP-245/244).

• Zebra (fork) — Zcash consensus node in Rust, extended with the Circle‑STARK verifier and plumbing needed for PoC experiments. https://github.com/Ztarknet/zebra

• Madara (fork) — Starknet client / sequencer (Rust). Used as the Ztarknet L2 execution layer: RPC, mempool, block building, state commitments. https://github.com/Ztarknet/madara

• ztarknet (orchestration) — Main repo for docs and infra. Contains Docker Compose and Kubernetes manifests to spin up local devnets/testnets: sequencer, prover, and Zcash node(s). https://github.com/Ztarknet/ztarknet

• zcash_script (fork) — Script interpreter repo. Kept to support the opcode fallback path using the pure‑Rust interpreter (avoids C++ FFI). https://github.com/Ztarknet/zcash_script

1. Users send L2 transactions to a Starknet‑compatible sequencer (Madara).
2. The sequencer executes Cairo, updates the L2 state root, and emits execution traces.
3. A prover (Stwo/Cairo) produces a Circle‑STARK proof for the state transition.
4. A submitter publishes a Zcash transaction that includes the proof (via TZE or the opcode+v6 witness path).
5. Zcash nodes verify the proof during consensus and advance the on‑chain L2 anchor.

flowchart LR
  U[Users / dApps] --> RPC[Madara JSON-RPC]
  RPC --> MEM[Mempool]
  MEM --> EXE[Cairo Execution]
  EXE --> ST[L2 State Root]
  EXE --> TR[Execution Trace]
  TR --> PROV[Stwo/Cairo Prover]
  PROV --> SUB[Submitter]
  subgraph Zcash L1
    ZN[Zebra]
    TZE[TZE / Opcode Verify]
    CHAIN[Consensus]
  end
  SUB --> ZN
  ZN --> TZE --> CHAIN

• Run a devnet: see the ztarknet repo for Compose/K8s recipes and step‑by‑step notes.
• L1 experiments: use the Zebra fork to test verification on Zcash test networks.
• L2 experiments: use the Madara fork to execute Cairo programs and produce state roots.
• Opcode path: only needed if we go with the Script opcode approach; see the zcash_script fork.

• Keep changes minimal and auditable.
• Pin verifier versions and parameters; enforce strict size/runtime bounds.
• Be explicit about trade‑offs (data availability, fees, latency).

Open an issue in the relevant repo with concrete context (branch, command, logs). Discussions and design notes live in the ztarknet repo.