test(dash): S8 stratum-binding contract KAT (extranonce2 nonce64-slot)

Fenced test-only slice: pins the get_work() -> stratum job BINDING contract
(coinbase nonce64 / extranonce2 slot geometry + coinb1/coinb2 split and
reassembly that partitions the miner search space) against oracle
frstrtr/p2pool-dash @9a0a609 work.py:21,421,436-438.

6 KATs, all derived independently of the SUT (oracle contract + Python
sha256d goldens):
  Extranonce2WidthOraclePin  EXTRANONCE2_SIZE == COINBASE_NONCE_LENGTH == 8
  SplitBoundaryGeometry      coinb1=bytes[:off], coinb2=bytes[off+8:]
  ZeroNonceIsIdentity        zero nonce reassembles gentx byte-for-byte (:437)
  SlotIsolation              only the 8 slot bytes move across extranonce2
  BindingInjectivity         distinct extranonce2 -> distinct coinbase leaf
  GoldenLeafHashes           independent sha256d byte-parity anchors

Pure/socket-free/node-free (synthetic CoinbaseLayout, no dashd, no
sharechain). Touches only test/ + build.yml allowlist -> IDENTIFIER-neutral,
non-consensus, independently landable ahead of the migration GO. No
self-merge.

Author: frstrtr

.github/workflows/build.yml

@@ -88,7 +88,7 @@ jobs:
                     test_threading test_weights \
                     test_header_chain test_mempool test_template_builder \
                     test_doge_chain test_compact_blocks test_dash_x11_kat \
-                    test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_cb_payee test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node \
+                    test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_cb_payee test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node \
                     test_multiaddress_pplns test_pplns_stress \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
@@ -238,7 +238,7 @@ jobs:
                     test_threading test_weights \
                     test_header_chain test_mempool test_template_builder \
                     test_doge_chain test_compact_blocks test_dash_x11_kat \
-                    test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_cb_payee test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node \
+                    test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_cb_payee test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
                     test_v36_script_sorting test_v36_cross_impl_refhash \

test/CMakeLists.txt

@@ -318,6 +318,16 @@ if (BUILD_TESTING AND GTest_FOUND)
     target_link_libraries(test_dash_work_job_targets PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining)  # OBJECT-lib SCC direct-naming (#22/#39): core stratum/web_server TUs
     gtest_add_tests(test_dash_work_job_targets "" AUTO)
 
+    add_executable(test_dash_stratum_binding test_dash_stratum_binding.cpp)
+    target_link_libraries(test_dash_stratum_binding PRIVATE
+        GTest::gtest_main GTest::gtest
+        dash_x11 core
+        nlohmann_json::nlohmann_json
+        ${Boost_LIBRARIES}
+    )
+    target_link_libraries(test_dash_stratum_binding PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining)  # OBJECT-lib SCC direct-naming (#22/#39)
+    gtest_add_tests(test_dash_stratum_binding "" AUTO)
+
     # share_init_verify gentx hash_link byte-parity vs oracle (coinbase_payload
     # VarStr prefix). Header-only over the dash_x11 + core link set; mirrors the
     # test_dash_conformance link set.

test/test_dash_stratum_binding.cpp

@@ -0,0 +1,171 @@
+// DASH S8 STRATUM-BINDING contract KAT.
+//
+// Pins the get_work() -> stratum job binding contract: the extranonce2
+// (nonce64) coinbase slot geometry and the coinb1/coinb2 split/reassembly
+// that partitions the miner search space. Where test_dash_work_job_targets
+// pins the job-TARGET arithmetic (work.py:368-426), this pins the coinbase
+// NONCE-BINDING half of the same get_work() path (work.py:21,421,436-438).
+//
+// ORACLE: frstrtr/p2pool-dash @9a0a609 p2pool/work.py
+//   :21   COINBASE_NONCE_LENGTH = 8
+//   :421  coinb1 = packed_gentx[:-payload - COINBASE_NONCE_LENGTH - 4]
+//   :436  assert len(coinbase_nonce) == COINBASE_NONCE_LENGTH
+//   :437  new_gentx = coinb1 + coinbase_nonce + packed_gentx[-payload-4:]
+//                     ... == packed_gentx  iff coinbase_nonce == '\0'*8
+// Every expected value below is derived from the oracle contract (or an
+// independent Python sha256d, see each golden), NOT from the SUT: a true
+// byte-parity pin, not a tautology.
+//
+// Pure / socket-free / node-free: no VM200/201 dashd, no live sharechain,
+// no template build -- the contract is exercised on a synthetic CoinbaseLayout
+// so the geometry/binding invariants stand alone from generate_transaction.
+
+#include <gtest/gtest.h>
+
+#include <cstddef>
+#include <numeric>
+#include <span>
+#include <string>
+#include <vector>
+
+#include <impl/dash/coinbase_builder.hpp>  // CoinbaseLayout, split_coinb, sha256d, EXTRANONCE2_SIZE
+#include <btclibs/util/strencodings.h>     // HexStr
+#include <core/uint256.hpp>
+
+using dash::coinbase::CoinbaseLayout;
+using dash::coinbase::CoinbSplit;
+using dash::coinbase::split_coinb;
+using dash::coinbase::sha256d;
+using dash::coinbase::EXTRANONCE2_SIZE;
+
+namespace {
+
+// Synthetic 40-byte coinbase: bytes[i] = i, with the 8-byte nonce64 slot at
+// [28,36) zeroed (nonce64_offset = 40 - locktime(4) - nonce64(8) = 28), mirroring
+// the real coinbase tail [... nonce64 8B][locktime 4B] for a type-0 tx.
+constexpr size_t kTotal  = 40;
+constexpr size_t kOffset = 28;   // = kTotal - 4 - 8
+
+CoinbaseLayout make_layout()
+{
+    CoinbaseLayout lay;
+    lay.bytes.resize(kTotal);
+    std::iota(lay.bytes.begin(), lay.bytes.end(), static_cast<unsigned char>(0));
+    for (size_t i = kOffset; i < kOffset + EXTRANONCE2_SIZE; ++i)
+        lay.bytes[i] = 0x00;
+    lay.nonce64_offset  = kOffset;
+    lay.ref_hash_offset = kOffset - 32;   // not exercised here; kept consistent
+    return lay;
+}
+
+// Reassemble coinb1 || extranonce2 || coinb2 as a stratum miner does, then
+// sha256d it -- the coinbase-hash leaf the miner feeds the merkle root.
+std::vector<unsigned char> reassemble(const CoinbaseLayout& lay,
+                                      std::span<const unsigned char> e2)
+{
+    std::vector<unsigned char> cb;
+    cb.reserve(lay.bytes.size());
+    cb.insert(cb.end(), lay.bytes.begin(), lay.bytes.begin() + lay.nonce64_offset);
+    cb.insert(cb.end(), e2.begin(), e2.end());
+    cb.insert(cb.end(), lay.bytes.begin() + lay.nonce64_offset + EXTRANONCE2_SIZE,
+              lay.bytes.end());
+    return cb;
+}
+
+uint256 hash_of(const std::vector<unsigned char>& b)
+{
+    return sha256d(std::span<const unsigned char>(b.data(), b.size()));
+}
+
+const unsigned char E2_A[8] = {1, 2, 3, 4, 5, 6, 7, 8};
+const unsigned char E2_B[8] = {0xde, 0xad, 0xbe, 0xef, 0xca, 0xfe, 0xf0, 0x0d};
+const unsigned char E2_ZERO[8] = {0, 0, 0, 0, 0, 0, 0, 0};
+
+}  // namespace
+
+// (1) Extranonce2 width == oracle COINBASE_NONCE_LENGTH (work.py:21). A width
+//     mismatch silently corrupts every miner submission, so pin it hard.
+TEST(DashStratumBinding, Extranonce2WidthOraclePin)
+{
+    EXPECT_EQ(EXTRANONCE2_SIZE, static_cast<size_t>(8));
+}
+
+// (2) Split boundary geometry (work.py:421). coinb1 is exactly bytes[:offset]
+//     and coinb2 is exactly bytes[offset+8:]. Lengths pinned from the layout,
+//     independent of the SUT's own hex.
+TEST(DashStratumBinding, SplitBoundaryGeometry)
+{
+    CoinbaseLayout lay = make_layout();
+    CoinbSplit s = split_coinb(lay);
+    EXPECT_EQ(s.coinb1_hex.size(), kOffset * 2);                       // hex chars
+    EXPECT_EQ(s.coinb2_hex.size(), (kTotal - kOffset - EXTRANONCE2_SIZE) * 2);
+    // coinb1 == HexStr(bytes[:offset]); coinb2 == HexStr(bytes[offset+8:]).
+    std::span<const unsigned char> b1(lay.bytes.data(), kOffset);
+    std::span<const unsigned char> b2(lay.bytes.data() + kOffset + EXTRANONCE2_SIZE,
+                                      kTotal - kOffset - EXTRANONCE2_SIZE);
+    EXPECT_EQ(s.coinb1_hex, HexStr(b1));
+    EXPECT_EQ(s.coinb2_hex, HexStr(b2));
+}
+
+// (3) Identity: reassembling coinb1 || '\0'*8 || coinb2 reproduces the coinbase
+//     bytes EXACTLY (work.py:437 -- coinbase_nonce == '\0'*8 => new_gentx == gentx).
+//     The zero nonce is the identity element of the binding.
+TEST(DashStratumBinding, ZeroNonceIsIdentity)
+{
+    CoinbaseLayout lay = make_layout();
+    CoinbSplit s = split_coinb(lay);
+    std::span<const unsigned char> z(E2_ZERO, EXTRANONCE2_SIZE);
+    EXPECT_EQ(s.coinb1_hex + HexStr(z) + s.coinb2_hex, HexStr(lay.bytes));
+    // ...and the reassembled bytes equal the original coinbase byte-for-byte.
+    EXPECT_EQ(reassemble(lay, z), lay.bytes);
+}
+
+// (4) Slot isolation: across distinct extranonce2 values, coinb1 and coinb2 are
+//     invariant and ONLY the 8 slot bytes move -- the reason a miner fetches
+//     coinb1/coinb2 once per job and iterates just the slot.
+TEST(DashStratumBinding, SlotIsolation)
+{
+    CoinbaseLayout lay = make_layout();
+    auto a = reassemble(lay, std::span<const unsigned char>(E2_A, 8));
+    auto b = reassemble(lay, std::span<const unsigned char>(E2_B, 8));
+    ASSERT_EQ(a.size(), lay.bytes.size());
+    ASSERT_EQ(b.size(), lay.bytes.size());
+    for (size_t i = 0; i < a.size(); ++i) {
+        if (i >= kOffset && i < kOffset + EXTRANONCE2_SIZE) continue;  // slot: may differ
+        EXPECT_EQ(a[i], b[i]) << "byte " << i << " outside slot must be invariant";
+    }
+    // slot region carries the supplied extranonce2 verbatim.
+    for (size_t i = 0; i < EXTRANONCE2_SIZE; ++i) {
+        EXPECT_EQ(a[kOffset + i], E2_A[i]);
+        EXPECT_EQ(b[kOffset + i], E2_B[i]);
+    }
+}
+
+// (5) Binding injectivity: distinct extranonce2 -> distinct coinbase hash, and
+//     each differs from the zero-slot leaf. This is the search-space PARTITION
+//     guarantee -- overlapping leaves would let two miners claim one solution.
+TEST(DashStratumBinding, BindingInjectivity)
+{
+    CoinbaseLayout lay = make_layout();
+    uint256 h0 = hash_of(reassemble(lay, std::span<const unsigned char>(E2_ZERO, 8)));
+    uint256 hA = hash_of(reassemble(lay, std::span<const unsigned char>(E2_A, 8)));
+    uint256 hB = hash_of(reassemble(lay, std::span<const unsigned char>(E2_B, 8)));
+    EXPECT_NE(hA, hB);
+    EXPECT_NE(hA, h0);
+    EXPECT_NE(hB, h0);
+}
+
+// (6) Golden sha256d byte-parity anchors. Expected values computed independently
+//     in Python (hashlib sha256d, big-endian display), NOT from the SUT:
+//       base = bytes(range(40)); base[28:36] = 0
+//       zero/A/B insert '\0'*8 / 01..08 / deadbeefcafef00d at [28:36)
+TEST(DashStratumBinding, GoldenLeafHashes)
+{
+    CoinbaseLayout lay = make_layout();
+    EXPECT_EQ(hash_of(reassemble(lay, std::span<const unsigned char>(E2_ZERO, 8))).GetHex(),
+              "b0d22de8e7f6765f9d8c289ecd77ad8e0ab6a88c2a4ccf594c509d7775bb54ab");
+    EXPECT_EQ(hash_of(reassemble(lay, std::span<const unsigned char>(E2_A, 8))).GetHex(),
+              "9bdc1a3b7b8600535e99c5298b6cb50fde48bd1b20a1ad6883abfbb2799b1b0e");
+    EXPECT_EQ(hash_of(reassemble(lay, std::span<const unsigned char>(E2_B, 8))).GetHex(),
+              "a0acea5d125dd3452a24dd84c0d1245450dd237cfe0bc0170d4381195e5f8061");
+}