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The Proof Chain

Every registration produces one proof. These proofs form a chain of state transitions from genesis:

genesis_root (empty tree -- known constant)
  |
  +-- Proof 1: "alice" registered at block 100, txid abc...
  |   old_root = genesis_root --> new_root_1
  |
  +-- Proof 2: "bob" registered at block 105, txid def...
  |   old_root = new_root_1 --> new_root_2
  |
  +-- Proof 3: "carol" registered at block 110, txid 789...
      old_root = new_root_2 --> new_root_3 (= current root)

Each proof's old_root must equal the previous proof's new_root. The first proof's old_root must equal the known genesis root (an empty Sparse Merkle Tree).

Verifying the Chain​

A verifier checks the entire registration history in five steps:

  1. Get the SP1 verification key -- deterministically derived from the guest program binary
  2. Fetch all proofs from the API
  3. Verify each SP1 proof using the verification key
  4. Check the chain -- genesis == P1.old_root, P1.new_root == P2.old_root, ..., PN.new_root == current_root
  5. Spot-check on-chain -- look up any committed txid on a Zcash node and confirm the memo, value, and block match

If all checks pass, the entire registration history is correct -- no trust in the indexer needed.

Proof Pipeline​

The scanner and prover run independently:

Zcash Blockchain
       |
   ZNS Scanner  (validates, captures SMT state)
       |
   SQLite DB    (status: "pending")
       |
   SP1 Prover   (generates ZK proof, verifies it)
       |
   SQLite DB    (status: "proved")
       |
   API Server   (GET /v1/proof/{name})

The scanner never blocks on proof generation. The prover daemon polls for pending records and can run on separate hardware.