Dapps have been asking for message signing to prove key control — identity
verification, SIWX-style login, and publishing a signed statement on chain. This
adds the construction and the verification; the protocol wiring follows
separately.
The known workaround is a dummy transaction: one input with a null outpoint, its
prevout script set to the P2PKH of the key being proven, one OP_RETURN output
carrying a server nonce, signed but never broadcast. It covers login, but not the
rest. A signature made that way is bound to a transaction, so verifying it means
rebuilding that exact transaction and knowing how it was serialised — it cannot
be published in an OP_RETURN and checked later by a third party holding only the
message, the signature and an address. It also asks a wallet to sign a real
transaction preimage, which is one bug away from signing a genuine spend.
So this produces the portable form: the standard "Bitcoin Signed Message"
construction. BCH wallets kept Bitcoin's magic string verbatim, so a signature
made here verifies in Electron Cash, Electrum and `bitcoin-cli verifymessage`.
The magic prefix also guarantees the digest can never coincide with a transaction
sighash, which makes signing a message categorically safer to approve than
signing a dummy transaction.
Address-level API, because that is what verification actually looks like
elsewhere: Electron Cash exposes only `verify_message(address, sig, message)`,
and a third party pulling a proof off an explorer has an address, not a public
key. verifyMessageSignatureForAddress accepts CashAddr with or without a prefix
and legacy base58, and rejects P2SH — no message signature can prove control of a
script hash.
recoverMessageSigner returns { publicKey, compressed } rather than a bare key.
The header byte declares which serialisation was used, and a key's compressed and
uncompressed forms hash to DIFFERENT addresses. Dropping that bit is how a
signature proving control of one address gets accepted as proof of another;
message-signing.test.ts pins the case in both directions.
signBitcoinMessage takes the private key as an argument and never retains it. It
exists so a wallet calls one function instead of reassembling the magic string,
both compactSize prefixes and the header byte — the parts third-party verifiers
check, and the parts covered by the tests here.
Testing: the byte layout is not asserted against our own reimplementation of the
spec, because that catches a coding mistake but not a misreading of it.
message-signing.vectors.json holds 32 vectors generated by a real Electron Cash
4.4.5 install (contrib/generate-message-signing-vectors.py) — two keys, both
compression forms, eight messages including empty, multi-byte UTF-8, multi-line
and the 252/253-byte compactSize boundary. Every preimage hash must match byte
for byte, and every signature must verify. Signature bytes are NOT portable
across implementations — Electron Cash and libauth derive the ECDSA nonce
differently — so the reproducible quantity is the hash.
message-signing.compat.test.ts drives `electron-cash verifymessage` directly,
closing the loop that vectors cannot: that our OUTPUT is accepted. Not part of
`npm test` (each assertion spawns a full Electron Cash process); run
`npm run test:compat -w @wizardconnect/core`. Skips when Electron Cash is
absent, so CI is unaffected.
77 tests, 426 in core.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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|---|---|---|
| contrib | ||
| docs | ||
| linters | ||
| packages | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| CLAUDE.md | ||
| eslint.config.cjs | ||
| LICENSE.txt | ||
| package-lock.json | ||
| package.json | ||
| README.md | ||
| tsconfig.base.json | ||
| zensical.toml | ||
WizardConnect
A dapp-to-wallet protocol built for Bitcoin Cash.
WizardConnect lets a dapp scan a wallet's QR code and immediately start deriving addresses, constructing transactions, and requesting signatures — no seed phrases, no trusted servers, no round trips.
Why not WalletConnect?
WalletConnect was built for Ethereum, where a wallet is a single address. BCH wallets are HD wallets with thousands of addresses for privacy. Forcing an Ethereum protocol onto BCH means:
- One address per session. WalletConnect gives the dapp a single address. That breaks the HD wallet model and destroys the privacy that multiple addresses provide.
- Unreliable on BCH. BCH support in WalletConnect is a second-class citizen — a bridge on top of an Ethereum-native protocol. Connections drop, sessions fail to restore, and there's no community maintaining it for BCH.
WizardConnect replaces all of this with a protocol designed from the ground up for UTXO chains and HD wallets.
How it works
Wallet Relay Dapp
│ │ │
│ ◄───── QR code scan ────── │ ◄──── shows QR (wiz://...) │
│ │ │
│ wallet_ready ──────────────►│──────────────────────────────►│
│ (xpubs + key exchange) │ │
│ │ derive addresses │
│ │ locally from xpubs │
│ │ (no more round trips)│
│ │ │
│ ◄──────────────────────────│◄──── sign_transaction_request │
│ user approves on wallet │ │
│ sign_transaction_response──►│──────────────────────────────►│
│ │ broadcast │
- The dapp generates a
wiz://URI and displays it as a QR code. - The wallet scans the QR, connects to the relay, and sends its xpubs.
- The dapp derives all addresses locally — no further contact with the wallet needed for address generation.
- When the dapp needs a signature, it sends a request. The user approves on the wallet. The signed transaction comes back.
All communication is end-to-end encrypted via Nostr NIP-17 gift wrap. The relay sees only ciphertext.
Key features
Full HD wallet support. The wallet shares BIP32 xpubs for specific derivation paths (receive, change, DeFi). The dapp derives unlimited addresses locally. No more single-address sessions.
Zero round trips for addresses. After the initial handshake, the dapp never needs to ask the wallet for a public key. It derives them on demand from the xpubs, in microseconds.
Decentralized transport. Built on Nostr — an open protocol with hundreds of public relays. No proprietary bridge server. Users can point to any relay for additional privacy or self-host their own.
Reconnection-proof. Both sides can disconnect and reconnect independently (app switch, browser refresh, network drop) and converge back to a live session without user action.
Extensible. The protocol negotiates capabilities during the handshake.
hdwalletv1 is the first protocol; future protocols (multisig, post-quantum,
token-aware) can be added without breaking existing connections.
Open source (LGPL-3.0). Free to use in commercial and non-commercial applications. Modifications to the library itself must be shared back.
Packages
npm install @wizardconnect/core # transport, protocol types, key exchange
npm install @wizardconnect/dapp # dapp-side session + address derivation
npm install @wizardconnect/wallet # wallet-side connection + signing
| Package | Description |
|---|---|
@wizardconnect/core |
Relay client, NIP-17 encryption, URI encoding, protocol message types |
@wizardconnect/dapp |
DappConnectionManager, DappPubkeyStateManager — session management and on-demand pubkey derivation |
@wizardconnect/wallet |
WalletConnectionManager, WalletAdapter interface — multi-connection management and sign request dispatch |
Quick start: dapp
import { initiateDappRelay } from "@wizardconnect/core";
import { DappConnectionManager } from "@wizardconnect/dapp";
const dapp = new DappConnectionManager("My Dapp", "https://example.com/icon.png");
const relay = initiateDappRelay(
(payload) => dapp.updateConnection(payload.client, payload.status),
{ explicitRelayUrls: ["wss://relay.riften.net:443"] },
);
// Display relay.uri as a QR code for the wallet to scan
dapp.on("walletready", () => {
// Connected! Derive addresses locally:
const receivePubkey = dapp.getPubkey(0, 0n); // receive path, index 0
const changePubkey = dapp.getPubkey(1, 0n); // change path, index 0
});
Quick start: wallet
import { WalletConnectionManager } from "@wizardconnect/wallet";
const manager = new WalletConnectionManager(myWalletAdapter);
// When the user scans a dapp's QR code:
const connectionId = manager.connect("wiz://?p=...&s=...");
// When a sign request arrives, show it to the user:
manager.on("pendingSignRequest", async ({ connectionId, request }) => {
const approved = await showApprovalUI(request);
if (approved) {
await manager.sendSignResponse(connectionId, request.sequence, signedTxHex);
} else {
await manager.sendSignError(connectionId, request.sequence, "User rejected");
}
});
See wallet integration guide for WalletAdapter implementation details.
Privacy model
WizardConnect shares xpubs at the chain level, not the account level. A dapp receiving the receive xpub can derive receive addresses but cannot derive change addresses or any other internal wallet activity. This is the same level of key material used by watch-only wallets.
For wallets that want stronger isolation, the protocol supports per-session xpub rotation — the dapp sees only the xpub node, never the derivation path.
See xpub sharing: why it's safe for a full discussion.
Security
- Private keys never leave the wallet. Signing happens on-device.
- All relay traffic is end-to-end encrypted (NIP-17 gift wrap). The relay cannot read messages.
- Key exchange includes an 8-byte shared secret (embedded in the QR code) for MITM prevention.
- No trusted intermediary. The relay is a dumb message broker — compromise it and you get ciphertext.
Documentation
| Topic | Link |
|---|---|
| Protocol messages and handshake | protocol.md |
| Connection URI and key exchange | connection-uri.md |
| Relay transport and encryption | transport.md |
| Wallet integration guide | wallet.md |
| Dapp integration guide | dapp.md |
| xpub delivery and derivation | pubkey-derivation.md |
| xpub sharing: why it's safe | xpub-sharing.md |
Building
npm install
npm run build # builds all packages in dependency order
npm run test # unit tests (fast, no network)
Integration tests hit a live relay:
cd packages/wallet && npm run test:integration
License
LGPL-3.0-or-later. Free for commercial and non-commercial use. Modifications to the library must be released under the same license.
Built by Riften Labs.