Подпись сообщений Bitcoin: разбор BIP-137 и BIP-322

import { secp256k1 } from "@noble/curves/secp256k1.js";
import { ripemd160 } from "@noble/hashes/legacy.js";
import { sha256 } from "@noble/hashes/sha2.js";
import { bech32, bech32m, createBase58check } from "@scure/base";

const b58 = createBase58check(sha256);
const sha256d = (b) => sha256(sha256(Uint8Array.from(b)));
const hash160 = (b) => ripemd160(sha256(b));
const utf8 = (s) => new TextEncoder().encode(s);
const cat = (...parts) => Uint8Array.from(parts.flatMap((p) => [...p]));
const varint = (n) => (n < 0xfd ? [n] : [0xfd, n & 0xff, n >> 8]); // messages under 64 KiB
export const NETWORKS = {
  mainnet: { p2pkh: 0x00, p2sh: 0x05, hrp: "bc" },
  regtest: { p2pkh: 0x6f, p2sh: 0xc4, hrp: "bcrt" },
};

/** Addresses of one compressed public key. */
export function addressesOf(pubkey, net = NETWORKS.mainnet) {
  const h = hash160(pubkey);
  const redeem = cat([0x00, 0x14], h); // P2SH-P2WPKH redeem script
  return {
    p2pkh: b58.encode(cat([net.p2pkh], h)),
    "p2sh-p2wpkh": b58.encode(cat([net.p2sh], hash160(redeem))),
    p2wpkh: bech32.encode(net.hrp, [0, ...bech32.toWords(h)]),
  };
}

/** scriptPubKey of an address, for BIP-322's message_challenge. */
export function scriptPubKey(address, net = NETWORKS.mainnet) {
  if (address.toLowerCase().startsWith(`${net.hrp}1`)) {
    const isV0 = address.toLowerCase().startsWith(`${net.hrp}1q`);
    const { words } = (isV0 ? bech32 : bech32m).decode(address);
    const program = (isV0 ? bech32 : bech32m).fromWords(words.slice(1));
    return cat([words[0] === 0 ? 0x00 : 0x50 + words[0], program.length], program);
  }
  const raw = b58.decode(address);
  if (raw[0] === net.p2pkh) return cat([0x76, 0xa9, 0x14], raw.slice(1), [0x88, 0xac]);
  if (raw[0] === net.p2sh) return cat([0xa9, 0x14], raw.slice(1), [0x87]);
  throw new Error(`unsupported address ${address}`);
}

// ---------------------------------------------------------------------------- BIP-137 (legacy)
/** The digest every legacy message signature covers. */
export const legacyDigest = (message) => {
  const m = utf8(message);
  return sha256d(cat([0x18], utf8("Bitcoin Signed Message:\n"), varint(m.length), m));
};
const HEADER_BASE = { p2pkh: 31, "p2sh-p2wpkh": 35, p2wpkh: 39 }; // compressed keys

/** 65-byte compact signature, base64. headerFor "electrum" keeps 31-34 for every address type. */
export function signLegacy(message, privateKey, type = "p2pkh", headerFor = "bip137") {
  const sig = secp256k1.Signature.fromBytes(secp256k1.sign(legacyDigest(message), privateKey, { prehash: false, format: "recovered" }), "recovered");
  const base = headerFor === "electrum" ? 31 : HEADER_BASE[type];
  return Buffer.from(cat([base + sig.recovery], sig.toBytes("compact"))).toString("base64");
}

/** Recovers the key and checks it against the address; strict mode also checks the header type. */
export function verifyLegacy(address, message, signatureBase64, { net = NETWORKS.mainnet, strict = false } = {}) {
  const raw = Buffer.from(signatureBase64, "base64");
  if (raw.length !== 65) throw new Error(`expected 65 bytes, got ${raw.length}`);
  const header = raw[0];
  if (header < 27 || header > 42) throw new Error(`header byte ${header} out of range`);
  const recovery = (header - 27) % 4;
  const typeFromHeader = header >= 39 ? "p2wpkh" : header >= 35 ? "p2sh-p2wpkh" : "p2pkh";
  const compressed = header >= 31;
  const sig = secp256k1.Signature.fromBytes(raw.subarray(1), "compact").addRecoveryBit(recovery);
  const pubkey = sig.recoverPublicKey(legacyDigest(message)).toBytes(compressed);
  const candidates = addressesOf(pubkey, net);
  const match = Object.entries(candidates).find(([, a]) => a === address)?.[0];
  if (!match) return { valid: false };
  if (strict && match !== typeFromHeader) return { valid: false, reason: `header says ${typeFromHeader}, address is ${match}` };
  return { valid: true, type: match, header };
}

// ---------------------------------------------------------------------------- BIP-322 (simple, P2WPKH)
const tag = sha256(utf8("BIP0322-signed-message"));
/** sha256(tag || tag || m), a BIP-340 tagged hash of the raw message. */
export const messageHash = (message) => sha256(cat(tag, tag, utf8(message)));
const le32 = (n) => [n & 0xff, (n >>> 8) & 0xff, (n >>> 16) & 0xff, n >>> 24];
const zero64 = new Array(8).fill(0);

/** The two virtual transactions of BIP-322, serialized without witness. Returns txids too. */
export function virtualTransactions(address, message, net = NETWORKS.mainnet) {
  const challenge = scriptPubKey(address, net);
  const toSpend = cat(
    le32(0), [1], new Array(32).fill(0), le32(0xffffffff), // version 0, one input spending 000…000:FFFFFFFF
    [34, 0x00, 0x20], messageHash(message), le32(0), // scriptSig OP_0 PUSH32[message_hash], nSequence 0
    [1], zero64, [challenge.length], challenge, le32(0), // one output, value 0, scriptPubKey = challenge
  );
  const toSpendId = sha256d(toSpend); // internal byte order
  const toSign = cat(le32(0), [1], toSpendId, le32(0), [0], le32(0), [1], zero64, [1, 0x6a], le32(0));
  const display = (h) => Buffer.from(h).reverse().toString("hex");
  return { challenge, toSpendId, toSpendTxid: display(toSpendId), toSignTxid: display(sha256d(toSign)) };
}

/** Verifies a BIP-322 simple signature for a P2WPKH address. Accepts the "smp" prefix or none. */
export function verifySimpleP2wpkh(address, message, signature, net = NETWORKS.mainnet) {
  const b64 = signature.startsWith("smp") ? signature.slice(3) : signature;
  const w = Buffer.from(b64, "base64");
  // Witness stack: count, then <len><DER sig + sighash byte>, <len><33-byte pubkey>.
  if (w[0] !== 2) throw new Error("expected a two-item witness stack");
  const sigWithType = w.subarray(2, 2 + w[1]);
  const pubkey = w.subarray(3 + w[1], 3 + w[1] + w[2 + w[1]]);
  const { challenge, toSpendId } = virtualTransactions(address, message, net);
  if (challenge[0] !== 0x00 || challenge[1] !== 20) throw new Error("not a P2WPKH address");
  if (Buffer.compare(Buffer.from(hash160(pubkey)), Buffer.from(challenge.subarray(2))) !== 0) return false;
  if (sigWithType.at(-1) !== 0x01) throw new Error("only SIGHASH_ALL is allowed");
  // BIP-143 digest of to_sign input 0, spending to_spend:0 worth 0 sat.
  const scriptCode = cat([0x19, 0x76, 0xa9, 0x14], challenge.subarray(2), [0x88, 0xac]);
  const outputs = cat(zero64, [1, 0x6a]);
  const preimage = cat(
    le32(0), sha256d(cat(toSpendId, le32(0))), sha256d(le32(0)), toSpendId, le32(0),
    scriptCode, zero64, le32(0), sha256d(outputs), le32(0), le32(1),
  );
  const der = sigWithType.subarray(0, -1);
  return secp256k1.verify(der, sha256d(preimage), pubkey, { prehash: false, format: "der", lowS: true });
}

#!/bin/sh
# Bitcoin Core in regtest: which address types can sign and verify messages, and the exact errors.
set -e
DATA=/tmp/regtest
mkdir -p "$DATA"
bitcoind -regtest -datadir="$DATA" -daemonwait -fallbackfee=0.0001 >/dev/null
cli() { bitcoin-cli -regtest -datadir="$DATA" "$@"; }
cli -named createwallet wallet_name=lab >/dev/null
echo "$(bitcoind -version | head -1)"

MSG="ecdsa.com lab, 2026-10-20"
for type in legacy p2sh-segwit bech32 bech32m; do
  addr=$(cli getnewaddress "" "$type")
  printf '%-12s %s\n' "$type" "$addr"
  if sig=$(cli signmessage "$addr" "$MSG" 2>/tmp/err); then
    echo "             signmessage: $sig"
    echo "             verifymessage: $(cli verifymessage "$addr" "$sig" "$MSG")"
    echo "$addr $sig" > "/w/core-$type.txt"
  else
    echo "             signmessage: $(tr '\n' ' ' < /tmp/err)"
  fi
done

# A signature made elsewhere for a segwit address: Core cannot even attempt it.
seg=$(cli getnewaddress "" bech32)
leg=$(cut -d' ' -f2 /w/core-legacy.txt)
echo "verifymessage with a bech32 address: $(cli verifymessage "$seg" "$leg" "$MSG" 2>&1 | tr '\n' ' ')"
cli stop >/dev/null

Bitcoin Core daemon version v31.1.0 bitcoind
legacy       mnaZRqP42LwTsVNQGfSb1eeTMvVzkaMoWp
             signmessage: ICZ/Fs0I/i7XNJbC+ubYkwpDZXI0uFZU1oaqrSaJlS+hYavTSzdfPKmRkLJrUdi6/RXl9WsYNEW5OU9l9hfMHCI=
             verifymessage: true
p2sh-segwit  2MyhmVFuFbTr4kAF1S4TtVmjEgkdouEntKK
             signmessage: error code: -3 error message: Address does not refer to key 
bech32       bcrt1qulxz0zapcld55a5twc9k88028y6dyxrggxug0n
             signmessage: error code: -3 error message: Address does not refer to key 
bech32m      bcrt1pq8x39vj0qay20825g8m3kffzx7sqwu9lfzmtjejta94luunwkmfsdc0hnd
             signmessage: error code: -3 error message: Address does not refer to key 
verifymessage with a bech32 address: error code: -3 error message: Address does not refer to key 

address mk1giEaBaAFPXNRMQcZNptPAp9kJmttKyp
core signature: H0bepOQGQpAS+FqLbBoVqjiXqArVq4AQlD59fhwpAX8bdTwCAlE407C2Ik9hTp5pxcsCv6C3arMw+bGjzYtH4mE=
our signature:  H0bepOQGQpAS+FqLbBoVqjiXqArVq4AQlD59fhwpAX8bdTwCAlE407C2Ik9hTp5pxcsCv6C3arMw+bGjzYtH4mE=
identical: yes
core verifymessage(our signature): true

// Same key, same message, P2WPKH address: the BIP-137 header and the Electrum convention, and who accepts which.
import { secp256k1 } from "@noble/curves/secp256k1.js";
import { Verifier } from "bip322-js";
import { addressesOf, signLegacy, verifyLegacy } from "./btcmsg.mjs";

const priv = secp256k1.utils.randomSecretKey();
const { p2pkh, p2wpkh } = addressesOf(secp256k1.getPublicKey(priv, true));
const message = "ecdsa.com lab, 2026-10-20";
const lib = (address, sig, strict) => {
  try {
    return Verifier.verifySignature(address, message, sig, strict);
  } catch (e) {
    return `throws: ${e.message}`;
  }
};
for (const [label, sig] of [
  ["BIP-137 header (39-42)", signLegacy(message, priv, "p2wpkh", "bip137")],
  ["Electrum header (31-34)", signLegacy(message, priv, "p2wpkh", "electrum")],
]) {
  const header = Buffer.from(sig, "base64")[0];
  const loose = verifyLegacy(p2wpkh, message, sig);
  const strict = verifyLegacy(p2wpkh, message, sig, { strict: true });
  console.log(`${label}: header ${header}`);
  console.log(`  ours, loose:  ${loose.valid}   ours, strict: ${strict.valid}${strict.reason ? ` (${strict.reason})` : ""}`);
  console.log(`  bip322-js, loose: ${lib(p2wpkh, sig, false)}   bip322-js, strict: ${lib(p2wpkh, sig, true)}`);
  console.log(`  same signature for the P2PKH address of the key: ours, loose ${verifyLegacy(p2pkh, message, sig).valid}`);
}

BIP-137 header (39-42): header 39
  ours, loose:  true   ours, strict: true
  bip322-js, loose: true   bip322-js, strict: true
  same signature for the P2PKH address of the key: ours, loose true
Electrum header (31-34): header 31
  ours, loose:  true   ours, strict: false (header says p2pkh, address is p2wpkh)
  bip322-js, loose: true   bip322-js, strict: false
  same signature for the P2PKH address of the key: ours, loose true

// BIP-322's published test vectors (addresses, messages and signatures only), against btcmsg.mjs and bip322-js 4.0.0.
import { readFileSync } from "node:fs";
import { Verifier } from "bip322-js";
import { messageHash, verifySimpleP2wpkh, virtualTransactions } from "./btcmsg.mjs";

const vectors = JSON.parse(readFileSync("bip322-basic-test-vectors.json", "utf8"));
for (const v of vectors.tx_hashes) {
  const { toSpendTxid, toSignTxid } = virtualTransactions(v.address, v.message);
  const ok = Buffer.from(messageHash(v.message)).toString("hex") === v.message_hash && toSpendTxid === v.to_spend_tx_hash && toSignTxid === v.to_sign_tx_hash;
  console.log(`hashes for ${JSON.stringify(v.message).padEnd(16).slice(0, 16)} message_hash, to_spend, to_sign match: ${ok}`);
}
for (const v of vectors.simple.filter((x) => x.type === "p2wpkh")) {
  for (const sig of v.bip322_signatures) {
    const ours = verifySimpleP2wpkh(v.address, v.message, sig);
    const call = (s) => { try { return Verifier.verifySignature(v.address, v.message, s); } catch (e) { return `throws: ${e.message}`; } };
    console.log(`${JSON.stringify(v.message).padEnd(14)} ${sig.slice(0, 12)}...  ours: ${ours} | bip322-js: ${call(sig)} | bip322-js, prefix removed: ${call(sig.slice(3))}`);
  }
}
const wrong = vectors.error.find((e) => e.description.startsWith("wrong message for valid simple p2wpkh"));
console.log(`error vector "${wrong.description}": ours ${verifySimpleP2wpkh(wrong.address, wrong.message, wrong.signature)}`);

hashes for ""               message_hash, to_spend, to_sign match: true
hashes for "Hello World"    message_hash, to_spend, to_sign match: true
hashes for "UTF-8 support:  message_hash, to_spend, to_sign match: true
""             smpAkcwRAIgM...  ours: true | bip322-js: throws: buffer too small | bip322-js, prefix removed: true
""             smpAkgwRQIhA...  ours: true | bip322-js: throws: buffer too small | bip322-js, prefix removed: true
"Hello World"  smpAkcwRAIgZ...  ours: true | bip322-js: throws: buffer too small | bip322-js, prefix removed: true
"Hello World"  smpAkgwRQIhA...  ours: true | bip322-js: throws: buffer too small | bip322-js, prefix removed: true
error vector "wrong message for valid simple p2wpkh signature (empty message was signed)": ours false