No integrity verification of downloaded ZK bytecode or trusted setup

[rachyandco]

Location: src/RnNoirModule.ts:54-82 (trusted setup), src/RnNoirModule.ts:113-147 (bytecode)

Issue: Circuit bytecode and the UltraPlonk trusted setup are downloaded from Google Cloud Storage with no checksum or hash check:

  // Trusted setup — no hash check
  const url =
  'https://storage.googleapis.com/rarimo-store/trusted-setups/ultraPlonkTrustedSetup.dat';
  await downloadResumable.downloadAsync();

  // Bytecode — same pattern, no hash check
  await downloadResumable.downloadAsync();

Impact: A compromised GCS bucket, CDN cache poisoning, or future supply-chain compromise could silently serve malicious bytecode that generates proofs with manipulated public inputs (e.g., wrong nullifiers, wrong citizenship claims). The user's device would compute and submit a proof they believe is correct but isn't.

Fix: Embed a hardcoded SHA-256 or BLAKE3 hash for each known-good file version. After download, compute the hash and reject mismatches before calling prove.