kernel: Generate a signet with a challenge

src/kernel/bitcoinkernel.cpp

@@ -45,6 +45,7 @@
 #include <functional>
 #include <list>
 #include <memory>
+#include <optional>
 #include <span>
 #include <stdexcept>
 #include <string>
@@ -822,6 +823,16 @@ btck_ChainParameters* btck_chain_parameters_create(const btck_ChainType chain_ty
     assert(false);
 }
 
+btck_ChainParameters* btck_chain_parameters_create_signet(const void* challenge, size_t challenge_len)
+{
+    assert(challenge != nullptr || challenge_len == 0);
+    const uint8_t* p = static_cast<const uint8_t*>(challenge);
+    CChainParams::SigNetOptions options{
+        .challenge = std::vector<uint8_t>{p, p + challenge_len},
+    };
+    return btck_ChainParameters::ref(const_cast<CChainParams*>(CChainParams::SigNet(options).release()));
+}
+
 btck_ChainParameters* btck_chain_parameters_copy(const btck_ChainParameters* chain_parameters)
 {
     return btck_ChainParameters::copy(chain_parameters);

src/kernel/bitcoinkernel.h

@@ -958,6 +958,18 @@ BITCOINKERNEL_API void btck_logging_connection_destroy(btck_LoggingConnection* l
 BITCOINKERNEL_API btck_ChainParameters* BITCOINKERNEL_WARN_UNUSED_RESULT btck_chain_parameters_create(
     btck_ChainType chain_type);
 
+/**
+ * @brief Create a signet chain parameters struct with a user-provided
+ * challenge.
+ *
+ * @param[in] challenge     The signet challenge value. Blocks must satisfy it in
+ *                          order to be valid.
+ * @param[in] challenge_len The length of the signet challenge.
+ * @return                  An allocated chain parameters opaque struct.
+ */
+BITCOINKERNEL_API btck_ChainParameters* BITCOINKERNEL_WARN_UNUSED_RESULT btck_chain_parameters_create_signet(
+    const void* challenge, size_t challenge_len);
+
 /**
  * Copy the chain parameters.
  */

src/kernel/bitcoinkernel_wrapper.h

@@ -1056,9 +1056,12 @@ public:
 class ChainParams : public Handle<btck_ChainParameters, btck_chain_parameters_copy, btck_chain_parameters_destroy>
 {
 public:
-    ChainParams(ChainType chain_type)
+    explicit ChainParams(ChainType chain_type)
         : Handle{btck_chain_parameters_create(static_cast<btck_ChainType>(chain_type))} {}
 
+    explicit ChainParams(std::span<const std::byte> signet_challenge)
+        : Handle{btck_chain_parameters_create_signet(signet_challenge.data(), signet_challenge.size())} {}
+
     ConsensusParamsView GetConsensusParams() const
     {
         return ConsensusParamsView{btck_chain_parameters_get_consensus_params(get())};

src/test/kernel/test_kernel.cpp

@@ -651,6 +651,13 @@ BOOST_AUTO_TEST_CASE(logging_tests)
     Logger logger{std::make_unique<TestLog>()};
 }
 
+BOOST_AUTO_TEST_CASE(btck_chainparams_tests)
+{
+    ChainParams params_signet{ChainType::SIGNET};
+    ChainParams params_signet_challenge{hex_string_to_byte_vec("51")};
+    CheckHandle(params_signet, params_signet_challenge);
+}
+
 BOOST_AUTO_TEST_CASE(btck_context_tests)
 {
     { // test default context