WizardConnect/packages/core/package.json
Håvard Kittelsen 763754b30e feat(core): Bitcoin Signed Message primitives, checked against Electron Cash
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>
2026-08-06 14:28:41 +02:00

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{
"name": "@wizardconnect/core",
"version": "0.2.0",
"type": "module",
"description": "Transport and protocol primitives for WizardConnect",
"repository": {
"type": "git",
"url": "https://gitlab.com/riftenlabs/lib/wizardconnect",
"directory": "packages/core"
},
"exports": {
".": {
"types": "./dist/index.d.ts",
"default": "./dist/index.js"
},
"./hdwalletv1-serialize": {
"types": "./dist/protocols/hdwalletv1-serialize.d.ts",
"default": "./dist/protocols/hdwalletv1-serialize.js"
}
},
"main": "dist/index.js",
"types": "dist/index.d.ts",
"files": [
"dist/"
],
"scripts": {
"build": "tsc",
"test": "vitest --config vitest.config.ts --run --passWithNoTests",
"test:compat": "vitest --config vitest.compat.config.ts --run",
"lint:prettier": "prettier --ignore-path ../../.gitignore . --list-different",
"lint:eslint": "eslint .",
"lint": "npm run lint:eslint && npm run lint:prettier",
"fix": "npm run fix:eslint && npm run fix:prettier",
"fix:prettier": "prettier --ignore-path ../../.gitignore . --write",
"fix:eslint": "npm run lint:eslint -- --fix"
},
"dependencies": {
"@bch-wc2/interfaces": "^0.0.8",
"nostr-tools": "^2.23.0",
"@bitauth/libauth": "^3.1.0-next.2",
"eventemitter3": "^5.0.1",
"isomorphic-ws": "^5.0.0",
"lossless-json": "^4.3.0",
"ws": "^8.18.0"
},
"devDependencies": {
"typescript": "^5.6.2",
"vitest": "^3.2.3"
}
}