Constructing the parameters for each Bitcoin network

501        }
502
503        m_chain_type = ChainType::SIGNET;
504        consensus.signet_blocks = true;
505        consensus.signet_challenge.assign(bin.begin(), bin.end());
506        consensus.nSubsidyHalvingInterval = 210000;
507        consensus.BIP34Height = 1;
508        consensus.BIP34Hash = uint256{};
509        consensus.BIP65Height = 1;
510        consensus.BIP66Height = 1;
511        consensus.CSVHeight = 1;
512        consensus.SegwitHeight = 1;
513        consensus.nPowTargetTimespan = 14 * 24 * 60 * 60; // two weeks
514        consensus.nPowTargetSpacing = 10 * 60;
515        consensus.fPowAllowMinDifficultyBlocks = false;
516        consensus.enforce_BIP94 = false;
517        consensus.fPowNoRetargeting = false;
518        consensus.MinBIP9WarningHeight = 0;
519        consensus.powLimit = uint256{"00000377ae000000000000000000000000000000000000000000000000000000"};
520        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].bit = 28;
521        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nStartTime = Consensus::BIP9Deployment::NEVER_ACTIVE;
522        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = Consensus::BIP9Deployment::NO_TIMEOUT;
523        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].min_activation_height = 0; // No activation delay
524        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].threshold = 1815; // 90%
525        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].period = 2016;
526
527        ApplyDeploymentOptions(options.dep_opts);
528
529        // message start is defined as the first 4 bytes of the sha256d of the block script
530        HashWriter h{};
531        h << consensus.signet_challenge;
532        uint256 hash = h.GetHash();
533        std::copy_n(hash.begin(), 4, pchMessageStart.begin());
534
535        nDefaultPort = 38333;
536        nPruneAfterHeight = 1000;
537
538        genesis = CreateGenesisBlock(1598918400, 52613770, 0x1e0377ae, 1, 50 * COIN);
539        consensus.hashGenesisBlock = genesis.GetHash();
540        assert(consensus.hashGenesisBlock == uint256{"00000008819873e925422c1ff0f99f7cc9bbb232af63a077a480a3633bee1ef6"});
541        assert(genesis.hashMerkleRoot == uint256{"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"});
542
543        m_assumeutxo_data = {
544            {
545                .height = 160'000,
546                .hash_serialized = AssumeutxoHash{uint256{"fe0a44309b74d6b5883d246cb419c6221bcccf0b308c9b59b7d70783dbdf928a"}},
547                .m_chain_tx_count = 2289496,
548                .blockhash = uint256{"0000003ca3c99aff040f2563c2ad8f8ec88bd0fd6b8f0895cfaf1ef90353a62c"},
549            },
550            {
551                .height = 290'000,
552                .hash_serialized = AssumeutxoHash{uint256{"97267e000b4b876800167e71b9123f1529d13b14308abec2888bbd2160d14545"}},
553                .m_chain_tx_count = 28547497,
554                .blockhash = uint256{"0000000577f2741bb30cd9d39d6d71b023afbeb9764f6260786a97969d5c9ac0"},
555            },
556            {
557                .height = 320'000,
558                .hash_serialized = AssumeutxoHash{uint256{"1aaf72ecb376cc16957fbb8d5d406bfd6e3165510e2fc83879b6d14cd20b4462"}},
559                .m_chain_tx_count = 32079110,
560                .blockhash = uint256{"0000000740ae66b284da84387dcfa14d7b1385b0bad482005ba4e770ea6c4b95"},
561            }
562        };
563
564        base58Prefixes[PUBKEY_ADDRESS] = std::vector<unsigned char>(1,111);
565        base58Prefixes[SCRIPT_ADDRESS] = std::vector<unsigned char>(1,196);
566        base58Prefixes[SECRET_KEY] =     std::vector<unsigned char>(1,239);
567        base58Prefixes[EXT_PUBLIC_KEY] = {0x04, 0x35, 0x87, 0xCF};
568        base58Prefixes[EXT_SECRET_KEY] = {0x04, 0x35, 0x83, 0x94};
569
570        bech32_hrp = "tb";
571
572        fDefaultConsistencyChecks = false;
573        m_is_mockable_chain = false;
574
575        // Generated by headerssync-params.py on 2026-09-08.
576        m_headers_sync_params = HeadersSyncParams{
577            .commitment_period = 629,
578            .redownload_buffer_size = 15885, // 15885/629 = ~25.3 commitments
579        };
580    }
581};
582
583/**
584 * Regression test: intended for private networks only. Has minimal difficulty to ensure that
585 * blocks can be found instantly.
586 */
587class CRegTestParams : public CChainParams
588{
589public:
590    explicit CRegTestParams(const RegTestOptions& opts)
591    {
592        m_chain_type = ChainType::REGTEST;
593        consensus.signet_blocks = false;
594        consensus.signet_challenge.clear();
595        consensus.nSubsidyHalvingInterval = 150;
596        consensus.BIP34Height = 1; // Always active unless overridden
597        consensus.BIP34Hash = uint256();
598        consensus.BIP65Height = 1;  // Always active unless overridden
599        consensus.BIP66Height = 1;  // Always active unless overridden
600        consensus.CSVHeight = 1;    // Always active unless overridden
601        consensus.SegwitHeight = 0; // Always active unless overridden
602        consensus.MinBIP9WarningHeight = 0;
603        consensus.powLimit = uint256{"7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"};
604        consensus.nPowTargetTimespan = 24 * 60 * 60; // one day
605        consensus.nPowTargetSpacing = 10 * 60;
606        consensus.fPowAllowMinDifficultyBlocks = true;
607        consensus.enforce_BIP94 = opts.enforce_bip94;
608        consensus.fPowNoRetargeting = true;
609
610        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].bit = 28;
611        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nStartTime = 0;
612        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = Consensus::BIP9Deployment::NO_TIMEOUT;
613        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].min_activation_height = 0; // No activation delay
614        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].threshold = 108; // 75%
615        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].period = 144; // Faster than normal for regtest (144 instead of 2016)
616
617        consensus.nMinimumChainWork = uint256{};
618        consensus.defaultAssumeValid = uint256{};
619
620        pchMessageStart[0] = 0xfa;
621        pchMessageStart[1] = 0xbf;
622        pchMessageStart[2] = 0xb5;
623        pchMessageStart[3] = 0xda;
624        nDefaultPort = 18444;
625        nPruneAfterHeight = opts.fastprune ? 100 : 1000;
626        m_assumed_blockchain_size = 0;
627        m_assumed_chain_state_size = 0;
628
629        ApplyDeploymentOptions(opts.dep_opts);
630
631        genesis = CreateGenesisBlock(1296688602, 2, 0x207fffff, 1, 50 * COIN);
632        consensus.hashGenesisBlock = genesis.GetHash();
633        assert(consensus.hashGenesisBlock == uint256{"0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206"});
634        assert(genesis.hashMerkleRoot == uint256{"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"});
635
636        vFixedSeeds.clear(); //!< Regtest mode doesn't have any fixed seeds.
637        vSeeds.clear();
638        vSeeds.emplace_back("dummySeed.invalid.");
639
640        fDefaultConsistencyChecks = true;
641        m_is_mockable_chain = true;
642
643        m_assumeutxo_data = {
644            {   // For use by unit tests
645                .height = 110,
646                .hash_serialized = AssumeutxoHash{uint256{"86e9a1205b418b16dde3a18a78c730e30137e28466bda5dbf6b33ab8fc05447c"}},
647                .m_chain_tx_count = 111,
648                .blockhash = uint256{"135eec25a6fb277884e5824e7aa7d052c4868161c99a5122170b5266f86c273d"},
649            },
650            {
651                // For use by fuzz target src/test/fuzz/utxo_snapshot.cpp
652                .height = 200,
653                .hash_serialized = AssumeutxoHash{uint256{"17dcc016d188d16068907cdeb38b75691a118d43053b8cd6a25969419381d13a"}},
654                .m_chain_tx_count = 201,
655                .blockhash = uint256{"385901ccbd69dff6bbd00065d01fb8a9e464dede7cfe0372443884f9b1dcf6b9"},
656            },
657            {
658                // For use by test/functional/feature_assumeutxo.py and test/functional/tool_bitcoin_chainstate.py
659                .height = 299,
660                .hash_serialized = AssumeutxoHash{uint256{"106b2c56233e378a824cf0d5ff2be42ed32c72f1605c9be288d00942908a40ac"}},
661                .m_chain_tx_count = 334,
662                .blockhash = uint256{"0c552ced4721c249a389eb9b08cb8da261cd46f0e7b5f9d064d48f3113406853"},
663            },
664        };
665
666        chainTxData = ChainTxData{
667            .nTime = 0,
668            .tx_count = 0,
669            .dTxRate = 0.001, // Set a non-zero rate to make it testable
670        };
671
672        base58Prefixes[PUBKEY_ADDRESS] = std::vector<unsigned char>(1,111);
673        base58Prefixes[SCRIPT_ADDRESS] = std::vector<unsigned char>(1,196);
674        base58Prefixes[SECRET_KEY] =     std::vector<unsigned char>(1,239);
675        base58Prefixes[EXT_PUBLIC_KEY] = {0x04, 0x35, 0x87, 0xCF};
676        base58Prefixes[EXT_SECRET_KEY] = {0x04, 0x35, 0x83, 0x94};
677
678        bech32_hrp = "bcrt";
679
680        // Copied from Testnet4.
681        m_headers_sync_params = HeadersSyncParams{
682            .commitment_period = 275,
683            .redownload_buffer_size = 7017, // 7017/275 = ~25.5 commitments
684        };
685    }
686};
687
688std::unique_ptr<const CChainParams> CChainParams::SigNet(const SigNetOptions& options)
689{
690    return std::make_unique<const SigNetParams>(options);
691}
692
693std::unique_ptr<const CChainParams> CChainParams::RegTest(const RegTestOptions& options)
694{
695    return std::make_unique<const CRegTestParams>(options);
696}
697
698std::unique_ptr<const CChainParams> CChainParams::Main(const MainNetOptions& options)
699{
700    return std::make_unique<const CMainParams>(options);
701}
702
703std::unique_ptr<const CChainParams> CChainParams::TestNet(const TestNetOptions& options)
704{
705    return std::make_unique<const CTestNetParams>(options);
706}
707
708std::unique_ptr<const CChainParams> CChainParams::TestNet4(const TestNetOptions& options)
709{
710    return std::make_unique<const CTestNet4Params>(options);
711}
712
713std::vector<int> CChainParams::GetAvailableSnapshotHeights() const
714{
715    std::vector<int> heights;
716    heights.reserve(m_assumeutxo_data.size());
717
718    for (const auto& data : m_assumeutxo_data) {
719        heights.emplace_back(data.height);
720    }
721    return heights;
722}
723
724std::optional<ChainType> GetNetworkForMagic(const MessageStartChars& message)
725{
726    const auto mainnet_msg = CChainParams::Main()->MessageStart();
727    const auto testnet_msg = CChainParams::TestNet()->MessageStart();
728    const auto testnet4_msg = CChainParams::TestNet4()->MessageStart();
729    const auto regtest_msg = CChainParams::RegTest()->MessageStart();
730    const auto signet_msg = CChainParams::SigNet()->MessageStart();
731
732    if (std::ranges::equal(message, mainnet_msg)) {
733        return ChainType::MAIN;
734    } else if (std::ranges::equal(message, testnet_msg)) {
735        return ChainType::TESTNET;
736    } else if (std::ranges::equal(message, testnet4_msg)) {
737        return ChainType::TESTNET4;
738    } else if (std::ranges::equal(message, regtest_msg)) {
739        return ChainType::REGTEST;
740    } else if (std::ranges::equal(message, signet_msg)) {
741        return ChainType::SIGNET;
742    }
743    return std::nullopt;
744}
745