Merge bitcoin#29252: kernel: Remove key module from kernel library

96378fe Refactor: Remove ECC_Start and ECC_Stop from key header (TheCharlatan)
41eba5b kernel: Remove key module from kernel library (TheCharlatan)
a08d2b3 tools: Use ECC_Context helper in bitcoin-tx and bitcoin-wallet tools (Ryan Ofsky)
28905c1 test: Use ECC_Context helper in bench and fuzz tests (Ryan Ofsky)
538fedd common: Add ECC_Context RAII wrapper for ECC_Start/ECC_Stop (Ryan Ofsky)

Pull request description:

  The key module's functionality is not used by the kernel library, but currently kernel users are still required to initialize the key module's `secp256k1_context_sign` global as part of the `kernel::Context` through `ECC_Start`. So move the `ECC_Start` call to the `NodeContext` ctor instead to completely remove the key module from the kernel library.

  The gui tests currently keep multiple `NodeContext` objects in memory, so call `ECC_Stop` manually to avoid triggering an assertion on `ECC_Start`.

  ---

  This PR is part of the [libbitcoinkernel project](bitcoin#27587). It removes a module from the kernel library.

ACKs for top commit:
  achow101:
    ACK 96378fe
  ryanofsky:
    Code review ACK 96378fe. Just suggested comment changes since last review.
  theuni:
    utACK 96378fe

Tree-SHA512: 40be427e8e2c920c0e3ce64a9bdd90551be27a89af11440bfb6ab0dd3a1d1ccb7cf1f82383cd782818cd1bb44d5ae5d2161cf4d78d3127ce4987342007090bab

src/Makefile.am

@@ -945,7 +945,6 @@ libbitcoinkernel_la_SOURCES = \
   kernel/disconnected_transactions.cpp \
   kernel/mempool_persist.cpp \
   kernel/mempool_removal_reason.cpp \
-  key.cpp \
   logging.cpp \
   node/blockstorage.cpp \
   node/chainstate.cpp \

src/bench/bip324_ecdh.cpp

@@ -14,7 +14,7 @@
 
 static void BIP324_ECDH(benchmark::Bench& bench)
 {
-    ECC_Start();
+    ECC_Context ecc_context{};
     FastRandomContext rng;
 
     std::array<std::byte, 32> key_data;
@@ -44,8 +44,6 @@ static void BIP324_ECDH(benchmark::Bench& bench)
         // - Copy 16 bytes from the resulting shared secret into the middle of their ellswift key.
         std::copy(ret.begin() + 16, ret.end(), their_ellswift_data.begin() + 24);
     });
-
-    ECC_Stop();
 }
 
 BENCHMARK(BIP324_ECDH, benchmark::PriorityLevel::HIGH);

src/bench/ccoins_caching.cpp

@@ -18,7 +18,7 @@
 // (https://github.com/bitcoin/bitcoin/issues/7883#issuecomment-224807484)
 static void CCoinsCaching(benchmark::Bench& bench)
 {
-    ECC_Start();
+    ECC_Context ecc_context{};
 
     FillableSigningProvider keystore;
     CCoinsView coinsDummy;
@@ -47,7 +47,6 @@ static void CCoinsCaching(benchmark::Bench& bench)
         bool success{AreInputsStandard(tx_1, coins)};
         assert(success);
     });
-    ECC_Stop();
 }
 
 BENCHMARK(CCoinsCaching, benchmark::PriorityLevel::HIGH);

src/bench/checkqueue.cpp

@@ -25,7 +25,7 @@ static void CCheckQueueSpeedPrevectorJob(benchmark::Bench& bench)
     // We shouldn't ever be running with the checkqueue on a single core machine.
     if (GetNumCores() <= 1) return;
 
-    ECC_Start();
+    ECC_Context ecc_context{};
 
     struct PrevectorJob {
         prevector<PREVECTOR_SIZE, uint8_t> p;
@@ -62,6 +62,5 @@ static void CCheckQueueSpeedPrevectorJob(benchmark::Bench& bench)
         // it is done explicitly here for clarity
         control.Wait();
     });
-    ECC_Stop();
 }
 BENCHMARK(CCheckQueueSpeedPrevectorJob, benchmark::PriorityLevel::HIGH);

src/bench/descriptors.cpp

@@ -12,7 +12,7 @@
 
 static void ExpandDescriptor(benchmark::Bench& bench)
 {
-    ECC_Start();
+    ECC_Context ecc_context{};
 
     const auto desc_str = "sh(wsh(multi(16,03669b8afcec803a0d323e9a17f3ea8e68e8abe5a278020a929adbec52421adbd0,0260b2003c386519fc9eadf2b5cf124dd8eea4c4e68d5e154050a9346ea98ce600,0362a74e399c39ed5593852a30147f2959b56bb827dfa3e60e464b02ccf87dc5e8,0261345b53de74a4d721ef877c255429961b7e43714171ac06168d7e08c542a8b8,02da72e8b46901a65d4374fe6315538d8f368557dda3a1dcf9ea903f3afe7314c8,0318c82dd0b53fd3a932d16e0ba9e278fcc937c582d5781be626ff16e201f72286,0297ccef1ef99f9d73dec9ad37476ddb232f1238aff877af19e72ba04493361009,02e502cfd5c3f972fe9a3e2a18827820638f96b6f347e54d63deb839011fd5765d,03e687710f0e3ebe81c1037074da939d409c0025f17eb86adb9427d28f0f7ae0e9,02c04d3a5274952acdbc76987f3184b346a483d43be40874624b29e3692c1df5af,02ed06e0f418b5b43a7ec01d1d7d27290fa15f75771cb69b642a51471c29c84acd,036d46073cbb9ffee90473f3da429abc8de7f8751199da44485682a989a4bebb24,02f5d1ff7c9029a80a4e36b9a5497027ef7f3e73384a4a94fbfe7c4e9164eec8bc,02e41deffd1b7cce11cde209a781adcffdabd1b91c0ba0375857a2bfd9302419f3,02d76625f7956a7fc505ab02556c23ee72d832f1bac391bcd2d3abce5710a13d06,0399eb0a5487515802dc14544cf10b3666623762fbed2ec38a3975716e2c29c232)))";
     const std::pair<int64_t, int64_t> range = {0, 1000};
@@ -27,8 +27,6 @@ static void ExpandDescriptor(benchmark::Bench& bench)
             assert(success);
         }
     });
-
-    ECC_Stop();
 }
 
 BENCHMARK(ExpandDescriptor, benchmark::PriorityLevel::HIGH);

src/bench/ellswift.cpp

@@ -9,7 +9,7 @@
 
 static void EllSwiftCreate(benchmark::Bench& bench)
 {
-    ECC_Start();
+    ECC_Context ecc_context{};
 
     CKey key = GenerateRandomKey();
     uint256 entropy = GetRandHash();
@@ -22,8 +22,6 @@ static void EllSwiftCreate(benchmark::Bench& bench)
         /* Use the last 32 bytes of the ellswift encoded public key as next entropy. */
         std::copy(ret.begin() + 32, ret.begin() + 64, MakeWritableByteSpan(entropy).begin());
     });
-
-    ECC_Stop();
 }
 
 BENCHMARK(EllSwiftCreate, benchmark::PriorityLevel::HIGH);

src/bench/verify_script.cpp

@@ -15,7 +15,7 @@
 // modified to measure performance of other types of scripts.
 static void VerifyScriptBench(benchmark::Bench& bench)
 {
-    ECC_Start();
+    ECC_Context ecc_context{};
 
     const uint32_t flags{SCRIPT_VERIFY_WITNESS | SCRIPT_VERIFY_P2SH};
     const int witnessversion = 0;
@@ -57,7 +57,6 @@ static void VerifyScriptBench(benchmark::Bench& bench)
         assert(err == SCRIPT_ERR_OK);
         assert(success);
     });
-    ECC_Stop();
 }
 
 static void VerifyNestedIfScript(benchmark::Bench& bench)

src/bitcoin-chainstate.cpp

@@ -26,6 +26,7 @@
 #include <script/sigcache.h>
 #include <util/chaintype.h>
 #include <util/fs.h>
+#include <util/signalinterrupt.h>
 #include <util/task_runner.h>
 #include <validation.h>
 #include <validationinterface.h>

src/bitcoin-tx.cpp

@@ -692,21 +692,10 @@ static void MutateTxSign(CMutableTransaction& tx, const std::string& flagStr)
     tx = mergedTx;
 }
 
-class Secp256k1Init
-{
-public:
-    Secp256k1Init() {
-        ECC_Start();
-    }
-    ~Secp256k1Init() {
-        ECC_Stop();
-    }
-};
-
 static void MutateTx(CMutableTransaction& tx, const std::string& command,
                      const std::string& commandVal)
 {
-    std::unique_ptr<Secp256k1Init> ecc;
+    std::unique_ptr<ECC_Context> ecc;
 
     if (command == "nversion")
         MutateTxVersion(tx, commandVal);
@@ -726,18 +715,18 @@ static void MutateTx(CMutableTransaction& tx, const std::string& command,
     else if (command == "outaddr")
         MutateTxAddOutAddr(tx, commandVal);
     else if (command == "outpubkey") {
-        ecc.reset(new Secp256k1Init());
+        ecc.reset(new ECC_Context());
         MutateTxAddOutPubKey(tx, commandVal);
     } else if (command == "outmultisig") {
-        ecc.reset(new Secp256k1Init());
+        ecc.reset(new ECC_Context());
         MutateTxAddOutMultiSig(tx, commandVal);
     } else if (command == "outscript")
         MutateTxAddOutScript(tx, commandVal);
     else if (command == "outdata")
         MutateTxAddOutData(tx, commandVal);
 
     else if (command == "sign") {
-        ecc.reset(new Secp256k1Init());
+        ecc.reset(new ECC_Context());
         MutateTxSign(tx, commandVal);
     }
 

src/bitcoin-wallet.cpp

@@ -128,10 +128,9 @@ MAIN_FUNCTION
         return EXIT_FAILURE;
     }
 
-    ECC_Start();
+    ECC_Context ecc_context{};
     if (!wallet::WalletTool::ExecuteWalletToolFunc(args, command->command)) {
         return EXIT_FAILURE;
     }
-    ECC_Stop();
     return EXIT_SUCCESS;
 }

src/bitcoind.cpp

@@ -14,11 +14,13 @@
 #include <init.h>
 #include <interfaces/chain.h>
 #include <interfaces/init.h>
+#include <kernel/context.h>
 #include <node/context.h>
 #include <node/interface_ui.h>
 #include <noui.h>
 #include <util/check.h>
 #include <util/exception.h>
+#include <util/signalinterrupt.h>
 #include <util/strencodings.h>
 #include <util/syserror.h>
 #include <util/threadnames.h>
@@ -180,6 +182,7 @@ static bool AppInit(NodeContext& node)
         }
 
         node.kernel = std::make_unique<kernel::Context>();
+        node.ecc_context = std::make_unique<ECC_Context>();
         if (!AppInitSanityChecks(*node.kernel))
         {
             // InitError will have been called with detailed error, which ends up on console

src/init.cpp

@@ -32,6 +32,8 @@
 #include <interfaces/chain.h>
 #include <interfaces/init.h>
 #include <interfaces/node.h>
+#include <kernel/context.h>
+#include <key.h>
 #include <logging.h>
 #include <mapport.h>
 #include <net.h>
@@ -75,6 +77,7 @@
 #include <util/fs_helpers.h>
 #include <util/moneystr.h>
 #include <util/result.h>
+#include <util/signalinterrupt.h>
 #include <util/strencodings.h>
 #include <util/string.h>
 #include <util/syserror.h>
@@ -371,6 +374,7 @@ void Shutdown(NodeContext& node)
     node.chainman.reset();
     node.validation_signals.reset();
     node.scheduler.reset();
+    node.ecc_context.reset();
     node.kernel.reset();
 
     RemovePidFile(*node.args);
@@ -1084,6 +1088,10 @@ bool AppInitSanityChecks(const kernel::Context& kernel)
         return InitError(strprintf(_("Initialization sanity check failed. %s is shutting down."), PACKAGE_NAME));
     }
 
+    if (!ECC_InitSanityCheck()) {
+        return InitError(strprintf(_("Elliptic curve cryptography sanity check failure. %s is shutting down."), PACKAGE_NAME));
+    }
+
     // Probe the data directory lock to give an early error message, if possible
     // We cannot hold the data directory lock here, as the forking for daemon() hasn't yet happened,
     // and a fork will cause weird behavior to it.

src/kernel/checks.cpp

@@ -4,8 +4,8 @@
 
 #include <kernel/checks.h>
 
-#include <key.h>
 #include <random.h>
+#include <util/result.h>
 #include <util/translation.h>
 
 #include <memory>
@@ -14,10 +14,6 @@ namespace kernel {
 
 util::Result<void> SanityChecks(const Context&)
 {
-    if (!ECC_InitSanityCheck()) {
-        return util::Error{Untranslated("Elliptic curve cryptography sanity check failure. Aborting.")};
-    }
-
     if (!Random_SanityCheck()) {
         return util::Error{Untranslated("OS cryptographic RNG sanity check failure. Aborting.")};
     }

src/kernel/context.cpp

@@ -5,9 +5,7 @@
 #include <kernel/context.h>
 
 #include <crypto/sha256.h>
-#include <key.h>
 #include <logging.h>
-#include <pubkey.h>
 #include <random.h>
 
 #include <string>
@@ -19,12 +17,7 @@ Context::Context()
     std::string sha256_algo = SHA256AutoDetect();
     LogPrintf("Using the '%s' SHA256 implementation\n", sha256_algo);
     RandomInit();
-    ECC_Start();
 }
 
-Context::~Context()
-{
-    ECC_Stop();
-}
 
 } // namespace kernel

src/kernel/context.h

@@ -5,10 +5,6 @@
 #ifndef BITCOIN_KERNEL_CONTEXT_H
 #define BITCOIN_KERNEL_CONTEXT_H
 
-#include <util/signalinterrupt.h>
-
-#include <memory>
-
 namespace kernel {
 //! Context struct holding the kernel library's logically global state, and
 //! passed to external libbitcoin_kernel functions which need access to this
@@ -19,7 +15,6 @@ namespace kernel {
 //! should be stored to std::unique_ptr members pointing to opaque types.
 struct Context {
     Context();
-    ~Context();
 };
 } // namespace kernel
 

src/key.cpp

@@ -432,7 +432,8 @@ bool ECC_InitSanityCheck() {
     return key.VerifyPubKey(pubkey);
 }
 
-void ECC_Start() {
+/** Initialize the elliptic curve support. May not be called twice without calling ECC_Stop first. */
+static void ECC_Start() {
     assert(secp256k1_context_sign == nullptr);
 
     secp256k1_context *ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
@@ -449,11 +450,22 @@ void ECC_Start() {
     secp256k1_context_sign = ctx;
 }
 
-void ECC_Stop() {
+/** Deinitialize the elliptic curve support. No-op if ECC_Start wasn't called first. */
+static void ECC_Stop() {
     secp256k1_context *ctx = secp256k1_context_sign;
     secp256k1_context_sign = nullptr;
 
     if (ctx) {
         secp256k1_context_destroy(ctx);
     }
 }
+
+ECC_Context::ECC_Context()
+{
+    ECC_Start();
+}
+
+ECC_Context::~ECC_Context()
+{
+    ECC_Stop();
+}

src/key.h

@@ -236,13 +236,21 @@ struct CExtKey {
     void SetSeed(Span<const std::byte> seed);
 };
 
-/** Initialize the elliptic curve support. May not be called twice without calling ECC_Stop first. */
-void ECC_Start();
-
-/** Deinitialize the elliptic curve support. No-op if ECC_Start wasn't called first. */
-void ECC_Stop();
-
 /** Check that required EC support is available at runtime. */
 bool ECC_InitSanityCheck();
 
+/**
+ * RAII class initializing and deinitializing global state for elliptic curve support.
+ * Only one instance may be initialized at a time.
+ *
+ * In the future global ECC state could be removed, and this class could contain
+ * state and be passed as an argument to ECC key functions.
+ */
+class ECC_Context
+{
+public:
+    ECC_Context();
+    ~ECC_Context();
+};
+
 #endif // BITCOIN_KEY_H

src/node/context.cpp

@@ -8,6 +8,7 @@
 #include <banman.h>
 #include <interfaces/chain.h>
 #include <kernel/context.h>
+#include <key.h>
 #include <net.h>
 #include <net_processing.h>
 #include <netgroup.h>
@@ -16,6 +17,7 @@
 #include <scheduler.h>
 #include <txmempool.h>
 #include <validation.h>
+#include <validationinterface.h>
 
 namespace node {
 NodeContext::NodeContext() = default;