Add deterministic RandomX block header hashing

src/primitives/block.cpp

@@ -5,11 +5,14 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <primitives/block.h>
+#include <crypto/randomx_hash.h>
 #include <crypto/common.h>
 #include <consensus/consensus.h>
 #include <chainparams.h>
 #include <hash.h>
+#include <streams.h>
 #include <tinyformat.h>
+#include <version.h>
 #include <arith_uint256.h>
 
 uint256 CBlockHeader::GetHash() const
@@ -36,6 +39,25 @@ uint256 CBlockHeader::GetPoWAlgoHash(const Consensus::Params& params) const
     return GetHash();
 }
 
+uint256 CBlockHeader::GetRandomXPoWHash(const uint256& seed) const
+{
+    CDataStream stream(SER_GETHASH, PROTOCOL_VERSION);
+    stream << *this;
+
+    uint256 result;
+
+    if (!VextaRandomXHash(
+            stream.data(),
+            stream.size(),
+            seed.data(),
+            seed.size(),
+            result.begin())) {
+        result.SetNull();
+    }
+
+    return result;
+}
+
 std::string CBlock::ToString(const Consensus::Params& params) const
 {
     std::stringstream s;

src/primitives/block.h

@@ -96,6 +96,14 @@ public:
 
     uint256 GetPoWAlgoHash(const Consensus::Params& params) const;
 
+    /**
+     * Calculate the RandomX proof-of-work hash using an explicit seed key.
+     *
+     * The input is the canonical serialized 80-byte block header.
+     * The seed is supplied in raw uint256 serialization byte order.
+     */
+    uint256 GetRandomXPoWHash(const uint256& seed) const;
+
     int64_t GetBlockTime() const
     {
         return (int64_t)nTime;