bip32_tests.cpp

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// Copyright (c) 2013-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <boost/test/unit_test.hpp>
 
#include <clientversion.h>
#include <key.h>
#include <key_io.h>
#include <streams.h>
#include <test/util/common.h>
#include <test/util/setup_common.h>
#include <util/bip32.h>
#include <util/strencodings.h>
 
#include <string>
#include <vector>
 
namespace {
 
struct TestDerivation {
    std::string pub;
    std::string prv;
    unsigned int nChild;
};
 
struct TestVector {
    std::string strHexMaster;
    std::vector<TestDerivation> vDerive;
 
    explicit TestVector(std::string strHexMasterIn) : strHexMaster(strHexMasterIn) {}
 
    TestVector& operator()(std::string pub, std::string prv, unsigned int nChild) {
        vDerive.emplace_back();
        TestDerivation &der = vDerive.back();
        der.pub = pub;
        der.prv = prv;
        der.nChild = nChild;
        return *this;
    }
};
 
TestVector test1 =
  TestVector("000102030405060708090a0b0c0d0e0f")
    ("xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8",
     "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi",
     BIP32_HARDENED_FLAG)
    ("xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw",
     "xprv9uHRZZhk6KAJC1avXpDAp4MDc3sQKNxDiPvvkX8Br5ngLNv1TxvUxt4cV1rGL5hj6KCesnDYUhd7oWgT11eZG7XnxHrnYeSvkzY7d2bhkJ7",
     1)
    ("xpub6ASuArnXKPbfEwhqN6e3mwBcDTgzisQN1wXN9BJcM47sSikHjJf3UFHKkNAWbWMiGj7Wf5uMash7SyYq527Hqck2AxYysAA7xmALppuCkwQ",
     "xprv9wTYmMFdV23N2TdNG573QoEsfRrWKQgWeibmLntzniatZvR9BmLnvSxqu53Kw1UmYPxLgboyZQaXwTCg8MSY3H2EU4pWcQDnRnrVA1xe8fs",
     BIP32_HARDENED_FLAG | 2)
    ("xpub6D4BDPcP2GT577Vvch3R8wDkScZWzQzMMUm3PWbmWvVJrZwQY4VUNgqFJPMM3No2dFDFGTsxxpG5uJh7n7epu4trkrX7x7DogT5Uv6fcLW5",
     "xprv9z4pot5VBttmtdRTWfWQmoH1taj2axGVzFqSb8C9xaxKymcFzXBDptWmT7FwuEzG3ryjH4ktypQSAewRiNMjANTtpgP4mLTj34bhnZX7UiM",
     2)
    ("xpub6FHa3pjLCk84BayeJxFW2SP4XRrFd1JYnxeLeU8EqN3vDfZmbqBqaGJAyiLjTAwm6ZLRQUMv1ZACTj37sR62cfN7fe5JnJ7dh8zL4fiyLHV",
     "xprvA2JDeKCSNNZky6uBCviVfJSKyQ1mDYahRjijr5idH2WwLsEd4Hsb2Tyh8RfQMuPh7f7RtyzTtdrbdqqsunu5Mm3wDvUAKRHSC34sJ7in334",
     1000000000)
    ("xpub6H1LXWLaKsWFhvm6RVpEL9P4KfRZSW7abD2ttkWP3SSQvnyA8FSVqNTEcYFgJS2UaFcxupHiYkro49S8yGasTvXEYBVPamhGW6cFJodrTHy",
     "xprvA41z7zogVVwxVSgdKUHDy1SKmdb533PjDz7J6N6mV6uS3ze1ai8FHa8kmHScGpWmj4WggLyQjgPie1rFSruoUihUZREPSL39UNdE3BBDu76",
     0);
 
TestVector test2 =
  TestVector("fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542")
    ("xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB",
     "xprv9s21ZrQH143K31xYSDQpPDxsXRTUcvj2iNHm5NUtrGiGG5e2DtALGdso3pGz6ssrdK4PFmM8NSpSBHNqPqm55Qn3LqFtT2emdEXVYsCzC2U",
     0)
    ("xpub69H7F5d8KSRgmmdJg2KhpAK8SR3DjMwAdkxj3ZuxV27CprR9LgpeyGmXUbC6wb7ERfvrnKZjXoUmmDznezpbZb7ap6r1D3tgFxHmwMkQTPH",
     "xprv9vHkqa6EV4sPZHYqZznhT2NPtPCjKuDKGY38FBWLvgaDx45zo9WQRUT3dKYnjwih2yJD9mkrocEZXo1ex8G81dwSM1fwqWpWkeS3v86pgKt",
     0xFFFFFFFF)
    ("xpub6ASAVgeehLbnwdqV6UKMHVzgqAG8Gr6riv3Fxxpj8ksbH9ebxaEyBLZ85ySDhKiLDBrQSARLq1uNRts8RuJiHjaDMBU4Zn9h8LZNnBC5y4a",
     "xprv9wSp6B7kry3Vj9m1zSnLvN3xH8RdsPP1Mh7fAaR7aRLcQMKTR2vidYEeEg2mUCTAwCd6vnxVrcjfy2kRgVsFawNzmjuHc2YmYRmagcEPdU9",
     1)
    ("xpub6DF8uhdarytz3FWdA8TvFSvvAh8dP3283MY7p2V4SeE2wyWmG5mg5EwVvmdMVCQcoNJxGoWaU9DCWh89LojfZ537wTfunKau47EL2dhHKon",
     "xprv9zFnWC6h2cLgpmSA46vutJzBcfJ8yaJGg8cX1e5StJh45BBciYTRXSd25UEPVuesF9yog62tGAQtHjXajPPdbRCHuWS6T8XA2ECKADdw4Ef",
     0xFFFFFFFE)
    ("xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL",
     "xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc",
     2)
    ("xpub6FnCn6nSzZAw5Tw7cgR9bi15UV96gLZhjDstkXXxvCLsUXBGXPdSnLFbdpq8p9HmGsApME5hQTZ3emM2rnY5agb9rXpVGyy3bdW6EEgAtqt",
     "xprvA2nrNbFZABcdryreWet9Ea4LvTJcGsqrMzxHx98MMrotbir7yrKCEXw7nadnHM8Dq38EGfSh6dqA9QWTyefMLEcBYJUuekgW4BYPJcr9E7j",
     0);
 
TestVector test3 =
  TestVector("4b381541583be4423346c643850da4b320e46a87ae3d2a4e6da11eba819cd4acba45d239319ac14f863b8d5ab5a0d0c64d2e8a1e7d1457df2e5a3c51c73235be")
    ("xpub661MyMwAqRbcEZVB4dScxMAdx6d4nFc9nvyvH3v4gJL378CSRZiYmhRoP7mBy6gSPSCYk6SzXPTf3ND1cZAceL7SfJ1Z3GC8vBgp2epUt13",
     "xprv9s21ZrQH143K25QhxbucbDDuQ4naNntJRi4KUfWT7xo4EKsHt2QJDu7KXp1A3u7Bi1j8ph3EGsZ9Xvz9dGuVrtHHs7pXeTzjuxBrCmmhgC6",
      BIP32_HARDENED_FLAG)
    ("xpub68NZiKmJWnxxS6aaHmn81bvJeTESw724CRDs6HbuccFQN9Ku14VQrADWgqbhhTHBaohPX4CjNLf9fq9MYo6oDaPPLPxSb7gwQN3ih19Zm4Y",
     "xprv9uPDJpEQgRQfDcW7BkF7eTya6RPxXeJCqCJGHuCJ4GiRVLzkTXBAJMu2qaMWPrS7AANYqdq6vcBcBUdJCVVFceUvJFjaPdGZ2y9WACViL4L",
      0);
 
TestVector test4 =
  TestVector("3ddd5602285899a946114506157c7997e5444528f3003f6134712147db19b678")
    ("xpub661MyMwAqRbcGczjuMoRm6dXaLDEhW1u34gKenbeYqAix21mdUKJyuyu5F1rzYGVxyL6tmgBUAEPrEz92mBXjByMRiJdba9wpnN37RLLAXa",
     "xprv9s21ZrQH143K48vGoLGRPxgo2JNkJ3J3fqkirQC2zVdk5Dgd5w14S7fRDyHH4dWNHUgkvsvNDCkvAwcSHNAQwhwgNMgZhLtQC63zxwhQmRv",
     BIP32_HARDENED_FLAG)
    ("xpub69AUMk3qDBi3uW1sXgjCmVjJ2G6WQoYSnNHyzkmdCHEhSZ4tBok37xfFEqHd2AddP56Tqp4o56AePAgCjYdvpW2PU2jbUPFKsav5ut6Ch1m",
     "xprv9vB7xEWwNp9kh1wQRfCCQMnZUEG21LpbR9NPCNN1dwhiZkjjeGRnaALmPXCX7SgjFTiCTT6bXes17boXtjq3xLpcDjzEuGLQBM5ohqkao9G",
     BIP32_HARDENED_FLAG | 1)
    ("xpub6BJA1jSqiukeaesWfxe6sNK9CCGaujFFSJLomWHprUL9DePQ4JDkM5d88n49sMGJxrhpjazuXYWdMf17C9T5XnxkopaeS7jGk1GyyVziaMt",
     "xprv9xJocDuwtYCMNAo3Zw76WENQeAS6WGXQ55RCy7tDJ8oALr4FWkuVoHJeHVAcAqiZLE7Je3vZJHxspZdFHfnBEjHqU5hG1Jaj32dVoS6XLT1",
     0);
 
const std::vector<std::string> TEST5 = {
    "xpub661MyMwAqRbcEYS8w7XLSVeEsBXy79zSzH1J8vCdxAZningWLdN3zgtU6LBpB85b3D2yc8sfvZU521AAwdZafEz7mnzBBsz4wKY5fTtTQBm",
    "xprv9s21ZrQH143K24Mfq5zL5MhWK9hUhhGbd45hLXo2Pq2oqzMMo63oStZzFGTQQD3dC4H2D5GBj7vWvSQaaBv5cxi9gafk7NF3pnBju6dwKvH",
    "xpub661MyMwAqRbcEYS8w7XLSVeEsBXy79zSzH1J8vCdxAZningWLdN3zgtU6Txnt3siSujt9RCVYsx4qHZGc62TG4McvMGcAUjeuwZdduYEvFn",
    "xprv9s21ZrQH143K24Mfq5zL5MhWK9hUhhGbd45hLXo2Pq2oqzMMo63oStZzFGpWnsj83BHtEy5Zt8CcDr1UiRXuWCmTQLxEK9vbz5gPstX92JQ",
    "xpub661MyMwAqRbcEYS8w7XLSVeEsBXy79zSzH1J8vCdxAZningWLdN3zgtU6N8ZMMXctdiCjxTNq964yKkwrkBJJwpzZS4HS2fxvyYUA4q2Xe4",
    "xprv9s21ZrQH143K24Mfq5zL5MhWK9hUhhGbd45hLXo2Pq2oqzMMo63oStZzFAzHGBP2UuGCqWLTAPLcMtD9y5gkZ6Eq3Rjuahrv17fEQ3Qen6J",
    "xprv9s2SPatNQ9Vc6GTbVMFPFo7jsaZySyzk7L8n2uqKXJen3KUmvQNTuLh3fhZMBoG3G4ZW1N2kZuHEPY53qmbZzCHshoQnNf4GvELZfqTUrcv",
    "xpub661no6RGEX3uJkY4bNnPcw4URcQTrSibUZ4NqJEw5eBkv7ovTwgiT91XX27VbEXGENhYRCf7hyEbWrR3FewATdCEebj6znwMfQkhRYHRLpJ",
    "xprv9s21ZrQH4r4TsiLvyLXqM9P7k1K3EYhA1kkD6xuquB5i39AU8KF42acDyL3qsDbU9NmZn6MsGSUYZEsuoePmjzsB3eFKSUEh3Gu1N3cqVUN",
    "xpub661MyMwAuDcm6CRQ5N4qiHKrJ39Xe1R1NyfouMKTTWcguwVcfrZJaNvhpebzGerh7gucBvzEQWRugZDuDXjNDRmXzSZe4c7mnTK97pTvGS8",
    "DMwo58pR1QLEFihHiXPVykYB6fJmsTeHvyTp7hRThAtCX8CvYzgPcn8XnmdfHGMQzT7ayAmfo4z3gY5KfbrZWZ6St24UVf2Qgo6oujFktLHdHY4",
    "DMwo58pR1QLEFihHiXPVykYB6fJmsTeHvyTp7hRThAtCX8CvYzgPcn8XnmdfHPmHJiEDXkTiJTVV9rHEBUem2mwVbbNfvT2MTcAqj3nesx8uBf9",
    "xprv9s21ZrQH143K24Mfq5zL5MhWK9hUhhGbd45hLXo2Pq2oqzMMo63oStZzF93Y5wvzdUayhgkkFoicQZcP3y52uPPxFnfoLZB21Teqt1VvEHx",
    "xprv9s21ZrQH143K24Mfq5zL5MhWK9hUhhGbd45hLXo2Pq2oqzMMo63oStZzFAzHGBP2UuGCqWLTAPLcMtD5SDKr24z3aiUvKr9bJpdrcLg1y3G",
    "xpub661MyMwAqRbcEYS8w7XLSVeEsBXy79zSzH1J8vCdxAZningWLdN3zgtU6Q5JXayek4PRsn35jii4veMimro1xefsM58PgBMrvdYre8QyULY",
    "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHL"
};
 
void RunTest(const TestVector& test)
{
    std::vector<std::byte> seed{ParseHex<std::byte>(test.strHexMaster)};
    CExtKey key;
    CExtPubKey pubkey;
    key.SetSeed(seed);
    pubkey = key.Neuter();
    for (const TestDerivation &derive : test.vDerive) {
        // Test serialization round trip
        DataStream ss{};
        ss << key;
        ss << pubkey;
        BOOST_CHECK_EQUAL(ss.size(), 2 * BIP32_EXTKEY_SIZE);
        CExtKey key_deser;
        CExtPubKey pubkey_deser;
        ss >> key_deser;
        ss >> pubkey_deser;
        BOOST_CHECK_EQUAL(key_deser, key);
        BOOST_CHECK_EQUAL(pubkey_deser, pubkey);
 
        // Test private key
        BOOST_CHECK(EncodeExtKey(key) == derive.prv);
        BOOST_CHECK_EQUAL(DecodeExtKey(derive.prv), key); //ensure a base58 decoded key also matches
 
        // Test public key
        BOOST_CHECK(EncodeExtPubKey(pubkey) == derive.pub);
        BOOST_CHECK_EQUAL(DecodeExtPubKey(derive.pub), pubkey); //ensure a base58 decoded pubkey also matches
 
        // Derive new keys
        CExtKey keyNew;
        BOOST_CHECK(key.Derive(keyNew, derive.nChild));
        CExtPubKey pubkeyNew = keyNew.Neuter();
        if (!(derive.nChild & BIP32_HARDENED_FLAG)) {
            // Compare with public derivation
            CExtPubKey pubkeyNew2;
            BOOST_CHECK(pubkey.Derive(pubkeyNew2, derive.nChild));
            BOOST_CHECK_EQUAL(pubkeyNew, pubkeyNew2);
        }
        key = keyNew;
        pubkey = pubkeyNew;
    }
}
 
}  // namespace
 
BOOST_FIXTURE_TEST_SUITE(bip32_tests, BasicTestingSetup)
 
BOOST_AUTO_TEST_CASE(bip32_test1) {
    RunTest(test1);
}
 
BOOST_AUTO_TEST_CASE(bip32_test2) {
    RunTest(test2);
}
 
BOOST_AUTO_TEST_CASE(bip32_test3) {
    RunTest(test3);
}
 
BOOST_AUTO_TEST_CASE(bip32_test4) {
    RunTest(test4);
}
 
BOOST_AUTO_TEST_CASE(bip32_test5) {
    for (const auto& str : TEST5) {
        auto dec_extkey = DecodeExtKey(str);
        auto dec_extpubkey = DecodeExtPubKey(str);
        BOOST_CHECK_MESSAGE(!dec_extkey.key.IsValid(), "Decoding '" + str + "' as xprv should fail");
        BOOST_CHECK_MESSAGE(!dec_extpubkey.pubkey.IsValid(), "Decoding '" + str + "' as xpub should fail");
    }
}
 
BOOST_AUTO_TEST_CASE(bip32_deserialize_invalid)
{
    // A serialized extended key is exactly BIP32_EXTKEY_SIZE bytes. A shorter
    // stream must throw rather than read past the end.
    for (size_t len{0}; len < BIP32_EXTKEY_SIZE; ++len) {
        CExtKey key;
        CExtPubKey pubkey;
        DataStream ss_key{std::vector<unsigned char>(len)};
        DataStream ss_pubkey{std::vector<unsigned char>(len)};
        BOOST_CHECK_THROW(ss_key >> key, std::ios_base::failure);
        BOOST_CHECK_THROW(ss_pubkey >> pubkey, std::ios_base::failure);
    }
 
    // Serialize a valid depth-0 xprv/xpub to mutate below.
    const CExtKey master{DecodeExtKey(test1.vDerive[0].prv)};
    const CExtPubKey master_pub{master.Neuter()};
    BOOST_REQUIRE(master.nDepth == 0);
    std::vector<unsigned char> key_bytes, pubkey_bytes;
    {
        DataStream ss{};
        ss << master;
        const auto ss_span{MakeUCharSpan(ss)};
        key_bytes.assign(ss_span.begin(), ss_span.end());
        DataStream sp{};
        sp << master_pub;
        const auto sp_span{MakeUCharSpan(sp)};
        pubkey_bytes.assign(sp_span.begin(), sp_span.end());
    }
    BOOST_CHECK_EQUAL(key_bytes.size(), BIP32_EXTKEY_SIZE);
    BOOST_CHECK_EQUAL(pubkey_bytes.size(), BIP32_EXTKEY_SIZE);
 
    // A longer stream is not invalid: exactly BIP32_EXTKEY_SIZE bytes are consumed
    // and the trailing byte is left unread.
    {
        std::vector<unsigned char> extra{key_bytes};
        extra.push_back(0);
        DataStream ss{extra};
        CExtKey key;
        ss >> key;
        BOOST_CHECK_EQUAL(key, master);
        BOOST_CHECK_EQUAL(ss.size(), 1);
    }
    {
        std::vector<unsigned char> extra{pubkey_bytes};
        extra.push_back(0);
        DataStream ss{extra};
        CExtPubKey pubkey;
        ss >> pubkey;
        BOOST_CHECK_EQUAL(pubkey, master_pub);
        BOOST_CHECK_EQUAL(ss.size(), 1);
    }
 
    const auto deser_extkey{[](std::vector<unsigned char> bytes) {
        DataStream ss{bytes};
        CExtKey key;
        ss >> key;
        return key;
    }};
    const auto deser_extpubkey{[](std::vector<unsigned char> bytes) {
        DataStream ss{bytes};
        CExtPubKey pubkey;
        ss >> pubkey;
        return pubkey;
    }};
 
    // Non-zero private key prefix (offset 41) => invalid.
    {
        auto bytes{key_bytes};
        bytes[41] = 1;
        BOOST_CHECK(!deser_extkey(bytes).key.IsValid());
    }
    // Non-zero child index with nDepth == 0 (offset 8) => invalid.
    {
        auto bytes{key_bytes};
        bytes[8] = 1;
        BOOST_CHECK(!deser_extkey(bytes).key.IsValid());
    }
    // Non-zero parent fingerprint with nDepth == 0 (offset 1) => invalid.
    {
        auto bytes{key_bytes};
        bytes[1] = 1;
        BOOST_CHECK(!deser_extkey(bytes).key.IsValid());
    }
    // Invalid public key header (offset 41) => invalid.
    {
        auto bytes{pubkey_bytes};
        bytes[41] = 0;
        BOOST_CHECK(!deser_extpubkey(bytes).pubkey.IsValid());
    }
    // Non-zero child index with nDepth == 0 (offset 8) => invalid.
    {
        auto bytes{pubkey_bytes};
        bytes[8] = 1;
        BOOST_CHECK(!deser_extpubkey(bytes).pubkey.IsValid());
    }
    // Non-zero parent fingerprint with nDepth == 0 (offset 1) => invalid.
    {
        auto bytes{pubkey_bytes};
        bytes[1] = 1;
        BOOST_CHECK(!deser_extpubkey(bytes).pubkey.IsValid());
    }
}
 
BOOST_AUTO_TEST_CASE(bip32_derive_ext_key)
{
    const CExtKey master{DecodeExtKey(test1.vDerive[0].prv)};
    const std::vector<uint32_t> path{test1.vDerive[0].nChild, test1.vDerive[1].nChild};
    const auto derived{DeriveExtKey(master, path)};
    BOOST_REQUIRE(derived);
    BOOST_CHECK(EncodeExtKey(derived->first) == test1.vDerive[2].prv);
 
    KeyOriginInfo expected_origin;
    expected_origin.fingerprint = master.id_key_fingerprint();
    expected_origin.path = path;
    BOOST_CHECK_EQUAL(derived->second, expected_origin);
 
    const auto root{DeriveExtKey(master, {})};
    BOOST_REQUIRE(root);
    BOOST_CHECK_EQUAL(root->first, master);
    expected_origin.path.clear();
    BOOST_CHECK_EQUAL(root->second, expected_origin);
 
    CExtKey max_depth{master};
    for (auto i{0}; i++ < 255;) {
        CExtKey next_key;
        BOOST_REQUIRE(max_depth.Derive(next_key, 0));
        max_depth = next_key;
    }
    BOOST_CHECK(!DeriveExtKey(max_depth, {0}));
}
 
BOOST_AUTO_TEST_CASE(bip32_has_hardened_derivation)
{
    const std::vector<uint32_t> empty;
    const std::vector<uint32_t> unhardened{0, 1, 2};
    const std::vector<uint32_t> hardened{BIP32_HARDENED_FLAG};
    const std::vector<uint32_t> mixed{0, BIP32_HARDENED_FLAG | 1, 2};
    BOOST_CHECK(!HasHardenedDerivation(empty));
    BOOST_CHECK(!HasHardenedDerivation(unhardened));
    BOOST_CHECK(HasHardenedDerivation(hardened));
    BOOST_CHECK(HasHardenedDerivation(mixed));
}
 
BOOST_AUTO_TEST_CASE(bip32_max_depth) {
    CExtKey key_parent{DecodeExtKey(test1.vDerive[0].prv)}, key_child;
    CExtPubKey pubkey_parent{DecodeExtPubKey(test1.vDerive[0].pub)}, pubkey_child;
 
    // We can derive up to the 255th depth..
    for (auto i = 0; i++ < 255;) {
        BOOST_CHECK(key_parent.Derive(key_child, 0));
        std::swap(key_parent, key_child);
        BOOST_CHECK(pubkey_parent.Derive(pubkey_child, 0));
        std::swap(pubkey_parent, pubkey_child);
    }
 
    // But trying to derive a non-existent 256th depth will fail!
    BOOST_CHECK(key_parent.nDepth == 255);
    BOOST_CHECK(pubkey_parent.nDepth == 255);
    BOOST_CHECK(!key_parent.Derive(key_child, 0));
    BOOST_CHECK(!pubkey_parent.Derive(pubkey_child, 0));
}
 
BOOST_AUTO_TEST_CASE(parse_hd_keypath)
{
    static constexpr uint32_t H0{0x80000000U}; // 0'
    static constexpr uint32_t H1{0x80000001U}; // 1'
 
    struct TestCase {
        bool is_valid;
        std::string keypath;
        std::vector<uint32_t> expected;
    };
 
    const std::vector<TestCase> tests{
        // 28 unhardened ones, no trailing slash
        {true,  "1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1",
                {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}},
        {false, "///////////////////////////", {}},
        // 26 unhardened ones, then hardened 1, then unhardened 1
        {true,  "1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1'/1",
                {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,H1,1}},
        {false, "//////////////////////////'/", {}},
        // 27 unhardened ones, trailing slash ignored
        {true,  "1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/",
                {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}},
        {false, "1///////////////////////////", {}},
        // 26 unhardened ones, hardened 1, trailing slash ignored
        {true,  "1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1'/",
                {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,H1}},
        {false, "1/'//////////////////////////", {}},
        {true,  "", {}},
        {false, " ", {}},
        {true,  "0", {0}},
        {false, "O", {}},
        {true,  "0000'/0000'/0000'", {H0, H0, H0}},
        {false, "0000,/0000,/0000,", {}},
        {true,  "01234", {1234}},
        {false, "0x1234", {}},
        {true,  "1", {1}},
        {false, " 1", {}},
        {true,  "42", {42}},
        {false, "m42", {}},
        // A path element's numeric part is capped at 2^31-1; the top bit is
        // reserved for the hardened marker (h or ').
        {true,  "2147483647", {0x7FFFFFFF}},  // 0x7fffffff, largest normal index
        {false, "2147483648", {}},  // 0x80000000, would set the hardened bit
        {false, "4294967295", {}},  // 0xffffffff
        {false, "4294967296", {}},  // 0xffffffff + 1
        {true,  "m", {}},
        {false, "n", {}},
        {true,  "m/", {}},
        {false, "n/", {}},
        {true,  "m/0", {0}},
        {false, "n/0", {}},
        {true,  "m/0'", {H0}},
        {false, "m/0''", {}},
 
        {true,  "m/0h", {H0}},
        {false, "m/0hh", {}},
        {false, "m/0x", {}},
        {false, "m/0a", {}},
        {false, "m/0G", {}},
        {false, "m/h0", {}},
        {true,  "m/0h/1h/2h", {H0, H1, 0x80000002U}},
        {true,  "m/0'/0'", {H0, H0}},
        {true,  "m/0h/0h", {H0, H0}},
        {true,  "m/0'/0h", {H0, H0}},
        {false, "m/'0/0'", {}},
        {false, "m/h0/0'", {}},
        {true,  "m/0/0", {0, 0}},
        {false, "n/0/0", {}},
        {true,  "m/0/0/00", {0, 0, 0}},
        {false, "m/0/0/f00", {}},
        {true,  "m/0/0/000000000000000000000000000000000000000000000000000000000000000000000000000000000000", {0, 0, 0}},
        {false, "m/1/1/111111111111111111111111111111111111111111111111111111111111111111111111111111111111", {}},
        {true,  "m/0/00/0", {0, 0, 0}},
        {false, "m/0'/00/'0", {}},
        {true,  "m/1/", {1}},
        {false, "m/1//", {}},
        // The cap applies to every element, wherever it sits in the path.
        {true,  "m/2147483647", {0x7FFFFFFF}},
        {false, "m/2147483648", {}},
        {false, "m/4294967295", {}},
        {false, "m/4294967296", {}},
        {true,  "m/0/2147483647", {0, 0x7FFFFFFF}},
        {false, "m/0/2147483648", {}},
        {false, "m/0/4294967295", {}},
        {false, "m/0/4294967296", {}},
        {false, "1/2H/3H", {}},
        {false, "1/2h/3h ", {}},
        {false, "1/2h /3h", {}},
        {true,  "1/2h/3h", {1, 0x80000002, 0x80000003}},
        {true,  "1/2'/3h", {1, 0x80000002, 0x80000003}},
    };
 
    for (const auto& [is_valid, keypath_str, expected] : tests) {
        std::vector<uint32_t> keypath_num;
        const bool res1{ParseHDKeypath(keypath_str, keypath_num)};
        if (!is_valid) {
            BOOST_CHECK_EQUAL(res1, false);
        } else {
            BOOST_CHECK_EQUAL(res1, true);
            BOOST_REQUIRE_EQUAL(keypath_num.size(), expected.size());
            for (size_t i{0}; i < keypath_num.size(); ++i) {
                BOOST_CHECK_EQUAL(keypath_num[i], expected[i]);
            }
 
            // Round-trip test:
            const std::string keypath_str2{FormatHDKeypath(keypath_num, /*apostrophe=*/true)};
            // Note keypath_str2 may differ from keypath_str. Leading '/' is not parsed, it is removed
            std::string keypath_str2_adjusted{keypath_str2};
            if (keypath_str2_adjusted.starts_with('/')) {
                keypath_str2_adjusted.erase(0, 1);
            }
            std::vector<uint32_t> keypath_num2;
            BOOST_CHECK(ParseHDKeypath(keypath_str2_adjusted, keypath_num2));
            BOOST_REQUIRE_EQUAL(keypath_num2.size(), keypath_num.size());
            for (size_t i{0}; i < keypath_num2.size(); ++i) {
                BOOST_CHECK_EQUAL(keypath_num2[i], keypath_num[i]);
            }
            const std::string keypath_str3{FormatHDKeypath(keypath_num2, /*apostrophe=*/true)};
            BOOST_CHECK_EQUAL(keypath_str3, keypath_str2);
        }
    }
}
 
BOOST_AUTO_TEST_SUITE_END()