BIP-137 と BIP-322 の比較｜Bitcoin のメッセージ署名

import { secp256k1 } from "@noble/curves/secp256k1.js";
import { ripemd160 } from "@noble/hashes/legacy.js";
import { sha256 } from "@noble/hashes/sha2.js";
import { bytesToHex, concatBytes, utf8ToBytes } from "@noble/hashes/utils.js";
import { base64, bech32, createBase58check } from "@scure/base";

const sha256d = (b) => sha256(sha256(b));
const u32 = (n) => new Uint8Array([n, n >>> 8, n >>> 16, n >>> 24]);
const zero = (n) => new Uint8Array(n);
const push = (b) => concatBytes(new Uint8Array([b.length]), b); // lengths here are all below 0xfd
const txid = (tx) => bytesToHex(sha256d(tx).reverse());

// Test key published in the BIP-322 basic test vectors (bip-0322/basic-test-vectors.json).
// It is public, so never send funds to its address.
const wif = createBase58check(sha256).decode("L3VFeEujGtevx9w18HD1fhRbCH67Az2dpCymeRE1SoPK6XQtaN2k");
const secretKey = wif.subarray(1, 33);
const pub = secp256k1.getPublicKey(secretKey, true);
const h160 = ripemd160(sha256(pub));
const address = bech32.encode("bc", [0, ...bech32.toWords(h160)]);
console.log("address:", address);

// BIP-137: double SHA-256 of a prefixed message, compact signature with a header byte
const message = "Hello World";
const m = utf8ToBytes(message);
const legacyHash = sha256d(concatBytes(push(utf8ToBytes("Bitcoin Signed Message:\n")), push(m)));
const rec = secp256k1.sign(legacyHash, secretKey, { prehash: false, format: "recovered" });
const encoded = base64.encode(concatBytes(new Uint8Array([39 + rec[0]]), rec.subarray(1))); // 39-42: P2WPKH
console.log("\nBIP-137 signature:", encoded);
// Verifier side: read the header, recover the public key, compare its hash with the address
const sig137 = base64.decode(encoded);
const recovered = secp256k1.recoverPublicKey(concatBytes(new Uint8Array([(sig137[0] - 27) & 3]), sig137.subarray(1)), legacyHash, { prehash: false });
console.log("header", sig137[0], "-> recovered key matches address:", bytesToHex(ripemd160(sha256(recovered))) === bytesToHex(h160));

// BIP-322: tagged message hash, virtual to_spend and to_sign transactions
const tag = sha256(utf8ToBytes("BIP0322-signed-message"));
const messageHash = sha256(concatBytes(tag, tag, m));
const challenge = concatBytes(new Uint8Array([0x00, 0x14]), h160); // P2WPKH scriptPubKey
const toSpend = concatBytes(u32(0), new Uint8Array([1]), zero(32), u32(0xffffffff),
  push(concatBytes(new Uint8Array([0x00, 0x20]), messageHash)), u32(0), new Uint8Array([1]), zero(8), push(challenge), u32(0));
const prevout = concatBytes(sha256d(toSpend), u32(0));
const opReturn = concatBytes(zero(8), push(new Uint8Array([0x6a])));
const toSign = concatBytes(u32(0), new Uint8Array([1]), prevout, push(zero(0)), u32(0), new Uint8Array([1]), opReturn, u32(0));
console.log("\nBIP-322 message hash:", bytesToHex(messageHash));
console.log("to_spend txid:", txid(toSpend));
console.log("to_sign txid: ", txid(toSign));

// Verify the "simple" signature from the test vectors: witness stack [signature, public key]
const vector = "smpAkcwRAIgZRfIY3p7/DoVTty6YZbWS71bc5Vct9p9Fia83eRmw2QCICK/ENGfwLtptFluMGs2KsqoNSk89pO7F29zJLUx9a/sASECx/EgAxlkQpQ9hYjgGu6EBCPMVPwVIVJqO4XCsMvViHI=";
const stack = base64.decode(vector.slice(3));
const der = stack.subarray(2, 2 + stack[1]);
const witnessKey = stack.subarray(3 + stack[1]);
// BIP-143 signature hash for input 0 of to_sign, SIGHASH_ALL
const scriptCode = push(concatBytes(new Uint8Array([0x76, 0xa9, 0x14]), h160, new Uint8Array([0x88, 0xac])));
const preimage = concatBytes(u32(0), sha256d(prevout), sha256d(u32(0)), prevout, scriptCode, zero(8), u32(0),
  sha256d(opReturn), u32(0), u32(1));
const ok = secp256k1.verify(der.subarray(0, -1), sha256d(preimage), witnessKey, { prehash: false, format: "der" });
console.log("vector signature:", vector.slice(0, 3), "prefix,", stack[0], "witness items,", ok ? "valid" : "invalid");
console.log("witness key is the address key:", bytesToHex(witnessKey) === bytesToHex(pub));

address: bc1q9vza2e8x573nczrlzms0wvx3gsqjx7vavgkx0l

BIP-137 signature: KOW2xi+ebJLeBtr674l4QH76dqDoVjLV80R9EFKFQX5rBrlCXPIZaYs8Yuayg0ZqjyiCbLy9pzZIS7JWT65/nsU=
header 40 -> recovered key matches address: true

BIP-322 message hash: f0eb03b1a75ac6d9847f55c624a99169b5dccba2a31f5b23bea77ba270de0a7a
to_spend txid: b79d196740ad5217771c1098fc4a4b51e0535c32236c71f1ea4d61a2d603352b
to_sign txid:  88737ae86f2077145f93cc4b153ae9a1cb8d56afa511988c149c5c8c9d93bddf
vector signature: smp prefix, 2 witness items, valid
witness key is the address key: true