Merge #18267: BIP-325: Signet [consensus]

8258c4c test: some sanity checks for consensus logic (Anthony Towns)
e47ad37 test: basic signet tests (Karl-Johan Alm)
4c189ab test: add small signet fuzzer (practicalswift)
ec9b25d test: signet network selection tests (Karl-Johan Alm)
3efe298 signet: hard-coded parameters for Signet Global Network VI (2020-09-07) (Karl-Johan Alm)
c7898bc qt: update QT to support signet network (Karl-Johan Alm)
a8de47a consensus: add signet validation (Karl-Johan Alm)
e8990f1 add signet chain and accompanying parameters (Karl-Johan Alm)
404682b add signet basic support (signet.cpp) (Karl-Johan Alm)
a2147d7 validation: move GetWitnessCommitmentIndex to consensus/validation (Karl-Johan Alm)

Pull request description:

  This PR is a part of BIP-325 (https://github.com/bitcoin/bips/blob/master/bip-0325.mediawiki), and is a sub-PR of #16411.

  * Signet consensus (this)
  * Signet RPC tools (pending)
  * Signet utility scripts (contrib/signet) (pending)

ACKs for top commit:
  jonatack:
    re-ACK 8258c4c per `git diff dbeea65 8258c4c`, only change since last review is updated `-signet*` config option naming.
  fjahr:
    re-ACK 8258c4c
  laanwj:
    ACK 8258c4c
  MarcoFalke:
    Approach ACK 8258c4c 🌵

Tree-SHA512: 5d158add96755910837feafa8214e13695b769a6aec3a2da753cf672618bef377fac43b0f4b772a87b25dd9f0c1c9b29f2789785d7a7d47a155cdcf48f7c975d

src/Makefile.am

@@ -202,6 +202,7 @@ BITCOIN_CORE_H = \
   script/signingprovider.h \
   script/standard.h \
   shutdown.h \
+  signet.h \
   streams.h \
   support/allocators/secure.h \
   support/allocators/zeroafterfree.h \
@@ -322,6 +323,7 @@ libbitcoin_server_a_SOURCES = \
   rpc/server.cpp \
   script/sigcache.cpp \
   shutdown.cpp \
+  signet.cpp \
   timedata.cpp \
   torcontrol.cpp \
   txdb.cpp \

src/Makefile.test.include

@@ -137,6 +137,7 @@ FUZZ_TARGETS = \
   test/fuzz/secp256k1_ecdsa_signature_parse_der_lax \
   test/fuzz/service_deserialize \
   test/fuzz/signature_checker \
+  test/fuzz/signet \
   test/fuzz/snapshotmetadata_deserialize \
   test/fuzz/span \
   test/fuzz/spanparsing \
@@ -1129,6 +1130,12 @@ test_fuzz_signature_checker_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_signature_checker_LDFLAGS = $(FUZZ_SUITE_LDFLAGS_COMMON)
 test_fuzz_signature_checker_SOURCES = test/fuzz/signature_checker.cpp
 
+test_fuzz_signet_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_signet_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_signet_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_signet_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_signet_SOURCES = test/fuzz/signet.cpp
+
 test_fuzz_snapshotmetadata_deserialize_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) -DSNAPSHOTMETADATA_DESERIALIZE=1
 test_fuzz_snapshotmetadata_deserialize_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_snapshotmetadata_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)

src/chainparams.cpp

@@ -7,6 +7,7 @@
 
 #include <chainparamsseeds.h>
 #include <consensus/merkle.h>
+#include <hash.h> // for signet block challenge hash
 #include <tinyformat.h>
 #include <util/system.h>
 #include <util/strencodings.h>
@@ -63,6 +64,8 @@ class CMainParams : public CChainParams {
 public:
     CMainParams() {
         strNetworkID = CBaseChainParams::MAIN;
+        consensus.signet_blocks = false;
+        consensus.signet_challenge.clear();
         consensus.nSubsidyHalvingInterval = 210000;
         consensus.BIP16Exception = uint256S("0x00000000000002dc756eebf4f49723ed8d30cc28a5f108eb94b1ba88ac4f9c22");
         consensus.BIP34Height = 227931;
@@ -172,6 +175,8 @@ class CTestNetParams : public CChainParams {
 public:
     CTestNetParams() {
         strNetworkID = CBaseChainParams::TESTNET;
+        consensus.signet_blocks = false;
+        consensus.signet_challenge.clear();
         consensus.nSubsidyHalvingInterval = 210000;
         consensus.BIP16Exception = uint256S("0x00000000dd30457c001f4095d208cc1296b0eed002427aa599874af7a432b105");
         consensus.BIP34Height = 21111;
@@ -250,13 +255,104 @@ class CTestNetParams : public CChainParams {
     }
 };
 
+/**
+ * Signet
+ */
+class SigNetParams : public CChainParams {
+public:
+    explicit SigNetParams(const ArgsManager& args) {
+        std::vector<uint8_t> bin;
+        vSeeds.clear();
+
+        if (!args.IsArgSet("-signetchallenge")) {
+            LogPrintf("Using default signet network\n");
+            bin = ParseHex("512103ad5e0edad18cb1f0fc0d28a3d4f1f3e445640337489abb10404f2d1e086be430210359ef5021964fe22d6f8e05b2463c9540ce96883fe3b278760f048f5189f2e6c452ae");
+            vSeeds.emplace_back("178.128.221.177");
+            vSeeds.emplace_back("2a01:7c8:d005:390::5");
+            vSeeds.emplace_back("ntv3mtqw5wt63red.onion:38333");
+        } else {
+            const auto signet_challenge = args.GetArgs("-signetchallenge");
+            if (signet_challenge.size() != 1) {
+                throw std::runtime_error(strprintf("%s: -signetchallenge cannot be multiple values.", __func__));
+            }
+            bin = ParseHex(signet_challenge[0]);
+
+            LogPrintf("Signet with challenge %s\n", signet_challenge[0]);
+        }
+
+        if (args.IsArgSet("-signetseednode")) {
+            vSeeds = args.GetArgs("-signetseednode");
+        }
+
+        strNetworkID = CBaseChainParams::SIGNET;
+        consensus.signet_blocks = true;
+        consensus.signet_challenge.assign(bin.begin(), bin.end());
+        consensus.nSubsidyHalvingInterval = 210000;
+        consensus.BIP34Height = 1;
+        consensus.BIP65Height = 1;
+        consensus.BIP66Height = 1;
+        consensus.CSVHeight = 1;
+        consensus.SegwitHeight = 1;
+        consensus.nPowTargetTimespan = 14 * 24 * 60 * 60; // two weeks
+        consensus.nPowTargetSpacing = 10 * 60;
+        consensus.fPowAllowMinDifficultyBlocks = false;
+        consensus.fPowNoRetargeting = false;
+        consensus.nRuleChangeActivationThreshold = 1916;
+        consensus.nMinerConfirmationWindow = 2016;
+        consensus.powLimit = uint256S("00000377ae000000000000000000000000000000000000000000000000000000");
+        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].bit = 28;
+        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nStartTime = 1199145601; // January 1, 2008
+        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = 1230767999; // December 31, 2008
+
+        // message start is defined as the first 4 bytes of the sha256d of the block script
+        CHashWriter h(SER_DISK, 0);
+        h << consensus.signet_challenge;
+        uint256 hash = h.GetHash();
+        memcpy(pchMessageStart, hash.begin(), 4);
+        LogPrintf("Signet derived magic (message start): %s\n", HexStr({pchMessageStart, pchMessageStart + 4}));
+
+        nDefaultPort = 38333;
+        nPruneAfterHeight = 1000;
+        m_assumed_blockchain_size = 0;
+        m_assumed_chain_state_size = 0;
+
+        genesis = CreateGenesisBlock(1598918400, 52613770, 0x1e0377ae, 1, 50 * COIN);
+        consensus.hashGenesisBlock = genesis.GetHash();
+        assert(consensus.hashGenesisBlock == uint256S("0x00000008819873e925422c1ff0f99f7cc9bbb232af63a077a480a3633bee1ef6"));
+        assert(genesis.hashMerkleRoot == uint256S("0x4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"));
+
+        vFixedSeeds.clear();
+
+        base58Prefixes[PUBKEY_ADDRESS] = std::vector<unsigned char>(1,111);
+        base58Prefixes[SCRIPT_ADDRESS] = std::vector<unsigned char>(1,196);
+        base58Prefixes[SECRET_KEY] =     std::vector<unsigned char>(1,239);
+        base58Prefixes[EXT_PUBLIC_KEY] = {0x04, 0x35, 0x87, 0xCF};
+        base58Prefixes[EXT_SECRET_KEY] = {0x04, 0x35, 0x83, 0x94};
+
+        bech32_hrp = "tb";
+
+        fDefaultConsistencyChecks = false;
+        fRequireStandard = true;
+        m_is_test_chain = true;
+        m_is_mockable_chain = false;
+
+        chainTxData = ChainTxData{
+            0,
+            0,
+            0
+        };
+    }
+};
+
 /**
  * Regression test
  */
 class CRegTestParams : public CChainParams {
 public:
     explicit CRegTestParams(const ArgsManager& args) {
         strNetworkID =  CBaseChainParams::REGTEST;
+        consensus.signet_blocks = false;
+        consensus.signet_challenge.clear();
         consensus.nSubsidyHalvingInterval = 150;
         consensus.BIP16Exception = uint256();
         consensus.BIP34Height = 500; // BIP34 activated on regtest (Used in functional tests)
@@ -391,12 +487,15 @@ const CChainParams &Params() {
 
 std::unique_ptr<const CChainParams> CreateChainParams(const std::string& chain)
 {
-    if (chain == CBaseChainParams::MAIN)
+    if (chain == CBaseChainParams::MAIN) {
         return std::unique_ptr<CChainParams>(new CMainParams());
-    else if (chain == CBaseChainParams::TESTNET)
+    } else if (chain == CBaseChainParams::TESTNET) {
         return std::unique_ptr<CChainParams>(new CTestNetParams());
-    else if (chain == CBaseChainParams::REGTEST)
+    } else if (chain == CBaseChainParams::SIGNET) {
+        return std::unique_ptr<CChainParams>(new SigNetParams(gArgs));
+    } else if (chain == CBaseChainParams::REGTEST) {
         return std::unique_ptr<CChainParams>(new CRegTestParams(gArgs));
+    }
     throw std::runtime_error(strprintf("%s: Unknown chain %s.", __func__, chain));
 }
 

src/chainparamsbase.cpp

@@ -13,6 +13,7 @@
 
 const std::string CBaseChainParams::MAIN = "main";
 const std::string CBaseChainParams::TESTNET = "test";
+const std::string CBaseChainParams::SIGNET = "signet";
 const std::string CBaseChainParams::REGTEST = "regtest";
 
 void SetupChainParamsBaseOptions(ArgsManager& argsman)
@@ -23,6 +24,9 @@ void SetupChainParamsBaseOptions(ArgsManager& argsman)
     argsman.AddArg("-segwitheight=<n>", "Set the activation height of segwit. -1 to disable. (regtest-only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-testnet", "Use the test chain. Equivalent to -chain=test.", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-vbparams=deployment:start:end", "Use given start/end times for specified version bits deployment (regtest-only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-signet", "Use the signet chain. Note that the network is defined by the -signetchallenge parameter", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-signetchallenge", "Blocks must satisfy the given script to be considered valid (only for signet networks; defaults to the global default signet test network challenge)", ArgsManager::ALLOW_STRING, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-signetseednode", "Specify a seed node for the signet network, in the hostname[:port] format, e.g. sig.net:1234 (may be used multiple times to specify multiple seed nodes; defaults to the global default signet test network seed node(s))", ArgsManager::ALLOW_STRING, OptionsCategory::CHAINPARAMS);
 }
 
 static std::unique_ptr<CBaseChainParams> globalChainBaseParams;
@@ -35,14 +39,16 @@ const CBaseChainParams& BaseParams()
 
 std::unique_ptr<CBaseChainParams> CreateBaseChainParams(const std::string& chain)
 {
-    if (chain == CBaseChainParams::MAIN)
+    if (chain == CBaseChainParams::MAIN) {
         return MakeUnique<CBaseChainParams>("", 8332);
-    else if (chain == CBaseChainParams::TESTNET)
+    } else if (chain == CBaseChainParams::TESTNET) {
         return MakeUnique<CBaseChainParams>("testnet3", 18332);
-    else if (chain == CBaseChainParams::REGTEST)
+    } else if (chain == CBaseChainParams::SIGNET) {
+        return MakeUnique<CBaseChainParams>("signet", 38332);
+    } else if (chain == CBaseChainParams::REGTEST) {
         return MakeUnique<CBaseChainParams>("regtest", 18443);
-    else
-        throw std::runtime_error(strprintf("%s: Unknown chain %s.", __func__, chain));
+    }
+    throw std::runtime_error(strprintf("%s: Unknown chain %s.", __func__, chain));
 }
 
 void SelectBaseParams(const std::string& chain)

src/chainparamsbase.h

@@ -21,6 +21,7 @@ class CBaseChainParams
     /** Chain name strings */
     static const std::string MAIN;
     static const std::string TESTNET;
+    static const std::string SIGNET;
     static const std::string REGTEST;
     ///@}
 

src/consensus/params.h

@@ -80,6 +80,13 @@ struct Params {
     int64_t DifficultyAdjustmentInterval() const { return nPowTargetTimespan / nPowTargetSpacing; }
     uint256 nMinimumChainWork;
     uint256 defaultAssumeValid;
+
+    /**
+     * If true, witness commitments contain a payload equal to a Bitcoin Script solution
+     * to the signet challenge. See BIP325.
+     */
+    bool signet_blocks{false};
+    std::vector<uint8_t> signet_challenge;
 };
 } // namespace Consensus
 

src/consensus/validation.h

@@ -12,6 +12,12 @@
 #include <primitives/transaction.h>
 #include <primitives/block.h>
 
+/** Index marker for when no witness commitment is present in a coinbase transaction. */
+static constexpr int NO_WITNESS_COMMITMENT{-1};
+
+/** Minimum size of a witness commitment structure. Defined in BIP 141. **/
+static constexpr size_t MINIMUM_WITNESS_COMMITMENT{38};
+
 /** A "reason" why a transaction was invalid, suitable for determining whether the
   * provider of the transaction should be banned/ignored/disconnected/etc.
   */
@@ -151,4 +157,25 @@ static inline int64_t GetTransactionInputWeight(const CTxIn& txin)
     return ::GetSerializeSize(txin, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(txin, PROTOCOL_VERSION) + ::GetSerializeSize(txin.scriptWitness.stack, PROTOCOL_VERSION);
 }
 
+/** Compute at which vout of the block's coinbase transaction the witness commitment occurs, or -1 if not found */
+inline int GetWitnessCommitmentIndex(const CBlock& block)
+{
+    int commitpos = NO_WITNESS_COMMITMENT;
+    if (!block.vtx.empty()) {
+        for (size_t o = 0; o < block.vtx[0]->vout.size(); o++) {
+            const CTxOut& vout = block.vtx[0]->vout[o];
+            if (vout.scriptPubKey.size() >= MINIMUM_WITNESS_COMMITMENT &&
+                vout.scriptPubKey[0] == OP_RETURN &&
+                vout.scriptPubKey[1] == 0x24 &&
+                vout.scriptPubKey[2] == 0xaa &&
+                vout.scriptPubKey[3] == 0x21 &&
+                vout.scriptPubKey[4] == 0xa9 &&
+                vout.scriptPubKey[5] == 0xed) {
+                commitpos = o;
+            }
+        }
+    }
+    return commitpos;
+}
+
 #endif // BITCOIN_CONSENSUS_VALIDATION_H

src/qt/guiconstants.h

@@ -46,6 +46,7 @@ static const int TOOLTIP_WRAP_THRESHOLD = 80;
 #define QAPP_ORG_DOMAIN "bitcoin.org"
 #define QAPP_APP_NAME_DEFAULT "Bitcoin-Qt"
 #define QAPP_APP_NAME_TESTNET "Bitcoin-Qt-testnet"
+#define QAPP_APP_NAME_SIGNET "Bitcoin-Qt-signet"
 #define QAPP_APP_NAME_REGTEST "Bitcoin-Qt-regtest"
 
 /* One gigabyte (GB) in bytes */

src/qt/networkstyle.cpp

@@ -19,7 +19,8 @@ static const struct {
 } network_styles[] = {
     {"main", QAPP_APP_NAME_DEFAULT, 0, 0},
     {"test", QAPP_APP_NAME_TESTNET, 70, 30},
-    {"regtest", QAPP_APP_NAME_REGTEST, 160, 30}
+    {"signet", QAPP_APP_NAME_SIGNET, 35, 15},
+    {"regtest", QAPP_APP_NAME_REGTEST, 160, 30},
 };
 static const unsigned network_styles_count = sizeof(network_styles)/sizeof(*network_styles);