COWL

Private receive links on Robinhood Chain.
ERC-5564 stealth addresses · ERC-6538 registry · live at cowl.pro

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COWL gives you one public link. Every payment sent to it lands at a fresh one-time address that only you can find and spend from. Anyone looking at the chain sees money going to a new address. They don't see that it's yours.

This repository is the full source of what runs at cowl.pro: the router contract, the cryptography, the web app, and the indexer.

How it works

1. Unlock keys. You sign one fixed message (free, moves nothing). Two private keys are derived from that signature in your browser: a spending key and a viewing key. Their public halves form your stealth meta-address (st:eth:0x…).
2. Share a link. Optionally register the meta-address in the canonical ERC-6538 Registry so payers can find it from your wallet address.
3. Payer sends. The payer's browser picks a random ephemeral key, computes a one-time address from your public keys, and calls CowlRouter. In one transaction, the router forwards the funds to that address and emits an ERC-5564 Announcement.
4. You scan. Your browser reads announcements and tests each one with the viewing key. A 1-byte view tag discards about 255 of every 256 foreign payments with a single curve multiplication.
5. You withdraw. For each match, the browser derives the one-time private key (spend + h mod n) and moves the funds wherever you choose.

Keys never leave the browser. The server only relays public Announcement logs.

Contracts (Robinhood Chain, chain id 4663)

Contract	Address	Notes
ERC-5564 Announcer	0x55649E01B5Df198D18D95b5cc5051630cfD45564	Canonical standard contract (CREATE2 address). Not ours.
ERC-6538 Registry	0x6538E6bf4B0eBd30A8Ea093027Ac2422ce5d6538	Canonical standard contract. Not ours.
CowlRouter	0x5A254fE1f65e5cbBe978095ab4632E7446Bd8590	contracts/src/CowlRouter.sol. Verified on Blockscout.
$COWL token	0xdCfa97774BA2cb8a9deD0612524984f6f46d4556	Launched on Pons V2.

CowlRouter properties:

• No owner, no admin functions, no upgrade path, no fee.
• It never holds a balance. ETH and tokens go straight to the one-time address.
• About 80 lines, with two external functions:
  • sendEth(stealth, ephemeralPubKey, viewTag)
  • sendToken(token, amount, stealth, ephemeralPubKey, viewTag), where any msg.value is forwarded as a small ETH gas tip so the receiver can move the token later.

Verify it yourself

You don't need to trust the website. Each of these checks takes a few minutes.

1. The deployed router is this code, byte for byte.

cd contracts
forge install foundry-rs/forge-std --no-git
forge build
jq -r .deployedBytecode.object out/CowlRouter.sol/CowlRouter.json | tr A-F a-f > local.txt
cast code 0x5A254fE1f65e5cbBe978095ab4632E7446Bd8590 --rpc-url https://robinhood-rpc.publicnode.com | tr A-F a-f > chain.txt
diff local.txt chain.txt && echo IDENTICAL

Expected keccak256 of the runtime code: 0xb52f6af50e9580100511ed88672e3056ccc85cd472e114088a5de74512ef692b (solc 0.8.26, cancun, optimizer 1,000,000 runs, bytecode_hash = "none").

2. It was tested with real funds before launch.

Step	Transaction
Router deployed, 18 Oct 2026 20:44 UTC	0x66dc0a7f…daaa1
First private payment (0.0002 ETH to a one-time address)	0x2540cd66…620bb
First withdrawal (found with the viewing key, moved with the one-time key)	0x4e28cf14…1ebc9ed

3. The router holds nothing. Its balance is shown on the Blockscout page linked above and on cowl.pro.

Repository layout

contracts/          Foundry project
  src/CowlRouter.sol      the router (exact verified source)
  test/CowlRouter.t.sol   fork tests against the live Announcer and real NVDA stock tokens
app/
  src/stealth.js          ERC-5564 scheme 1 cryptography (@noble/curves, @noble/hashes)
  src/chain.js            RPC, wallet discovery (EIP-6963), contract ABIs
  src/app.js              Receive / Send / Inbox / Withdraw
  src/landing.js, vault3d.js   landing page and the three.js vault
  src/token.js            $COWL section: market cap chart from on-chain curve trades
  pages/                  HTML (built into app/public)
  public/                 CSS, config.json, static assets
server/server.mjs   static server + announcement indexer (/api/announcements, /api/stats)
                    + $COWL trades read from the Pons bonding curve (/api/token)
test/
  stealth.test.mjs        offline unit tests for the cryptography
  e2e.mjs                 full flow on a local fork: register → send ETH + NVDA → scan → withdraw
tools/build.mjs     esbuild bundle

Code comments are written in Indonesian. Identifiers, UI text and this README are in English.

Run it

Requires Node 20+ and, for the contracts, Foundry.

npm install
npm test                 # offline crypto tests
npm run build            # bundle app + landing into app/public
npm start                # http://127.0.0.1:4791

Contract tests fork Robinhood Chain mainnet:

cd contracts
forge install foundry-rs/forge-std --no-git
forge test -j 1 -vv

End-to-end test on a local fork:

anvil --fork-url https://robinhood.api.pocket.network --chain-id 4663 --port 8645 &
(cd contracts && forge build)
npm run test:e2e

What it hides, and what it doesn't

Receiver's main wallet	Hidden. Each payment goes to a new one-time address.
Link between two payments	Hidden.
Receiver's private keys	Never shared. Derived and used only in the browser.
Amount and asset	Public. COWL does not encrypt amounts.
Sender's wallet	Public. The payer signs a normal transaction.
Withdrawal destination	Public. Withdrawing to your main wallet links that payment to it.

Limits, stated plainly:

• There is no independent audit yet. The router is short and verified, and the cryptography follows ERC-5564 scheme 1 using the audited @noble libraries.
• Robinhood stock tokens are issued with controls: the issuer can pause transfers or block addresses, and COWL cannot override that.
• Timing and amount patterns can still hint at who received a payment.

The message you sign is fixed in app/src/stealth.js. Any site that gets you to sign that exact text can derive your COWL keys, so sign it only on cowl.pro.

Links

• Site and app: https://cowl.pro
• Transparency page: https://cowl.pro/transparency
• X: https://x.com/cowlhq
• Telegram: https://t.me/cowlhq

License

MIT. The HDRI app/public/assets/studio.hdr is "Studio Small 09" from Poly Haven (CC0).