optimization: Migrate fixed-size obfuscation end-to-end from std::vector<std::byte> to uint64_t

Since `util::Xor` accepts `uint64_t` values, we're eliminating any repeated vector-to-uint64_t conversions going back to the loading/saving of these values (we're still serializing them as vectors, but converting as soon as possible to `uint64_t`). This is the reason the tests still generate vector values and convert to `uint64_t` later instead of generating it directly.

We're also short-circuit `Xor` calls with 0 key values early to avoid unnecessary calculations (e.g. `MakeWritableByteSpan`) - even assuming that XOR is never called for 0.

>  cmake -B build -DBUILD_BENCH=ON -DCMAKE_BUILD_TYPE=Release \
&& cmake --build build -j$(nproc) \
&& build/bin/bench_bitcoin -filter='XorObfuscationBench' -min-time=10000

C++ compiler .......................... AppleClang 17.0.0.17000013

|              ns/MiB |               MiB/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|           14,730.40 |           67,886.80 |    0.1% |     11.01 | `XorObfuscationBench`

C++ compiler .......................... GNU 13.3.0

|              ns/MiB |               MiB/s |    err% |         ins/MiB |         cyc/MiB |    IPC |        bra/MiB |   miss% |     total | benchmark
|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
|           51,187.17 |           19,536.15 |    0.0% |      327,683.95 |      183,747.58 |  1.783 |      65,536.55 |    0.0% |     11.00 | `XorObfuscationBench`

----

A few other benchmarks that seem to have improved as well (tested with Clang only):
Before:

|               ns/op |                op/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|        2,202,618.49 |              454.01 |    0.2% |     11.01 | `ReadBlockBench`
|          734,444.92 |            1,361.57 |    0.3% |     10.66 | `ReadRawBlockBench`

After:

|               ns/op |                op/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|        1,912,308.06 |              522.93 |    0.4% |     10.98 | `ReadBlockBench`
|           49,092.93 |           20,369.53 |    0.2% |     10.99 | `ReadRawBlockBench`

src/bench/xor.cpp

@@ -19,13 +19,12 @@ static void XorObfuscationBench(benchmark::Bench& bench)
     constexpr size_t bytes{10_MiB};
     auto test_data{rng.randbytes<std::byte>(bytes)};
 
-    std::vector key_bytes{rng.randbytes<std::byte>(8)};
-    uint64_t key;
-    std::memcpy(&key, key_bytes.data(), 8);
+    const Obfuscation obfuscation{rng.rand64()};
+    assert(obfuscation);
 
     size_t offset{0};
     bench.batch(bytes / 1_MiB).unit("MiB").run([&] {
-        util::Xor(test_data, key_bytes, offset++);
+        obfuscation(test_data, offset++);
         ankerl::nanobench::doNotOptimizeAway(test_data);
     });
 }

src/dbwrapper.cpp

@@ -173,7 +173,7 @@ void CDBBatch::Clear()
 void CDBBatch::WriteImpl(std::span<const std::byte> key, DataStream& ssValue)
 {
     leveldb::Slice slKey(CharCast(key.data()), key.size());
-    ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
+    dbwrapper_private::GetObfuscation(parent)(ssValue);
     leveldb::Slice slValue(CharCast(ssValue.data()), ssValue.size());
     m_impl_batch->batch.Put(slKey, slValue);
 }
@@ -215,6 +215,7 @@ struct LevelDBContext {
 CDBWrapper::CDBWrapper(const DBParams& params)
     : m_db_context{std::make_unique<LevelDBContext>()},
       m_name{fs::PathToString(params.path.stem())},
+      m_obfuscation{0},
       m_path{params.path},
       m_is_memory{params.memory_only}
 {
@@ -252,21 +253,22 @@ CDBWrapper::CDBWrapper(const DBParams& params)
     }
 
     {
-        obfuscate_key = std::vector<unsigned char>(OBFUSCATE_KEY_NUM_BYTES, '\000'); // Needed for unobfuscated Read
-        const bool key_missing{!Read(OBFUSCATE_KEY_KEY, obfuscate_key)};
+        m_obfuscation = 0; // Needed for unobfuscated Read
+        std::vector<unsigned char> obfuscate_key_vector(Obfuscation::SIZE_BYTES, '\000');
+        const bool key_missing{!Read(OBFUSCATE_KEY_KEY, obfuscate_key_vector)};
         if (key_missing && params.obfuscate && IsEmpty()) {
             // Initialize non-degenerate obfuscation if it won't upset existing, non-obfuscated data.
-            std::vector<uint8_t> new_key(OBFUSCATE_KEY_NUM_BYTES);
+            std::vector<uint8_t> new_key(Obfuscation::SIZE_BYTES);
             GetRandBytes(new_key);
 
             // Write `new_key` so we don't obfuscate the key with itself
             Write(OBFUSCATE_KEY_KEY, new_key);
-            obfuscate_key = new_key;
+            obfuscate_key_vector = new_key;
 
-            LogPrintf("Wrote new obfuscate key for %s: %s\n", fs::PathToString(params.path), HexStr(obfuscate_key));
+            LogPrintf("Wrote new obfuscate key for %s: %s\n", fs::PathToString(params.path), HexStr(obfuscate_key_vector));
         }
-
-        LogPrintf("Using obfuscation key for %s: %s\n", fs::PathToString(params.path), HexStr(obfuscate_key));
+        LogPrintf("Using obfuscation key for %s: %s\n", fs::PathToString(params.path), HexStr(obfuscate_key_vector));
+        m_obfuscation = obfuscate_key_vector;
     }
 }
 
@@ -317,9 +319,6 @@ size_t CDBWrapper::DynamicMemoryUsage() const
 // We must use a string constructor which specifies length so that we copy
 // past the null-terminator.
 const std::string CDBWrapper::OBFUSCATE_KEY_KEY("\000obfuscate_key", 14);
-
-const unsigned int CDBWrapper::OBFUSCATE_KEY_NUM_BYTES = 8;
-
 std::optional<std::string> CDBWrapper::ReadImpl(std::span<const std::byte> key) const
 {
     leveldb::Slice slKey(CharCast(key.data()), key.size());
@@ -402,6 +401,5 @@ void CDBIterator::SeekToFirst() { m_impl_iter->iter->SeekToFirst(); }
 void CDBIterator::Next() { m_impl_iter->iter->Next(); }
 
 namespace dbwrapper_private {
-const std::vector<unsigned char>& GetObfuscateKey(const CDBWrapper& w) { return w.obfuscate_key; }
-
+Obfuscation GetObfuscation(const CDBWrapper& w) { return w.m_obfuscation; }
 } // namespace dbwrapper_private

src/dbwrapper.h

@@ -63,8 +63,7 @@ namespace dbwrapper_private {
  * Database obfuscation should be considered an implementation detail of the
  * specific database.
  */
-const std::vector<unsigned char>& GetObfuscateKey(const CDBWrapper &w);
-
+Obfuscation GetObfuscation(const CDBWrapper&);
 }; // namespace dbwrapper_private
 
 bool DestroyDB(const std::string& path_str);
@@ -166,7 +165,7 @@ public:
     template<typename V> bool GetValue(V& value) {
         try {
             DataStream ssValue{GetValueImpl()};
-            ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
+            dbwrapper_private::GetObfuscation(parent)(ssValue);
             ssValue >> value;
         } catch (const std::exception&) {
             return false;
@@ -179,7 +178,7 @@ struct LevelDBContext;
 
 class CDBWrapper
 {
-    friend const std::vector<unsigned char>& dbwrapper_private::GetObfuscateKey(const CDBWrapper &w);
+    friend Obfuscation dbwrapper_private::GetObfuscation(const CDBWrapper&);
 private:
     //! holds all leveldb-specific fields of this class
     std::unique_ptr<LevelDBContext> m_db_context;
@@ -188,14 +187,11 @@ private:
     std::string m_name;
 
     //! a key used for optional XOR-obfuscation of the database
-    std::vector<unsigned char> obfuscate_key;
+    Obfuscation m_obfuscation;
 
     //! the key under which the obfuscation key is stored
     static const std::string OBFUSCATE_KEY_KEY;
 
-    //! the length of the obfuscate key in number of bytes
-    static const unsigned int OBFUSCATE_KEY_NUM_BYTES;
-
     //! path to filesystem storage
     const fs::path m_path;
 
@@ -226,7 +222,7 @@ public:
         }
         try {
             DataStream ssValue{MakeByteSpan(*strValue)};
-            ssValue.Xor(obfuscate_key);
+            m_obfuscation(ssValue);
             ssValue >> value;
         } catch (const std::exception&) {
             return false;

src/node/blockstorage.cpp

@@ -777,13 +777,13 @@ void BlockManager::UnlinkPrunedFiles(const std::set<int>& setFilesToPrune) const
 
 AutoFile BlockManager::OpenBlockFile(const FlatFilePos& pos, bool fReadOnly) const
 {
-    return AutoFile{m_block_file_seq.Open(pos, fReadOnly), m_xor_key};
+    return AutoFile{m_block_file_seq.Open(pos, fReadOnly), m_obfuscation};
 }
 
 /** Open an undo file (rev?????.dat) */
 AutoFile BlockManager::OpenUndoFile(const FlatFilePos& pos, bool fReadOnly) const
 {
-    return AutoFile{m_undo_file_seq.Open(pos, fReadOnly), m_xor_key};
+    return AutoFile{m_undo_file_seq.Open(pos, fReadOnly), m_obfuscation};
 }
 
 fs::path BlockManager::GetBlockPosFilename(const FlatFilePos& pos) const
@@ -1103,7 +1103,7 @@ FlatFilePos BlockManager::WriteBlock(const CBlock& block, int nHeight)
     return pos;
 }
 
-static auto InitBlocksdirXorKey(const BlockManager::Options& opts)
+static Obfuscation InitBlocksdirXorKey(const BlockManager::Options& opts)
 {
     // Bytes are serialized without length indicator, so this is also the exact
     // size of the XOR-key file.
@@ -1152,12 +1152,12 @@ static auto InitBlocksdirXorKey(const BlockManager::Options& opts)
         };
     }
     LogInfo("Using obfuscation key for blocksdir *.dat files (%s): '%s'\n", fs::PathToString(opts.blocks_dir), HexStr(xor_key));
-    return std::vector<std::byte>{xor_key.begin(), xor_key.end()};
+    return Obfuscation{xor_key};
 }
 
 BlockManager::BlockManager(const util::SignalInterrupt& interrupt, Options opts)
     : m_prune_mode{opts.prune_target > 0},
-      m_xor_key{InitBlocksdirXorKey(opts)},
+      m_obfuscation{InitBlocksdirXorKey(opts)},
       m_opts{std::move(opts)},
       m_block_file_seq{FlatFileSeq{m_opts.blocks_dir, "blk", m_opts.fast_prune ? 0x4000 /* 16kB */ : BLOCKFILE_CHUNK_SIZE}},
       m_undo_file_seq{FlatFileSeq{m_opts.blocks_dir, "rev", UNDOFILE_CHUNK_SIZE}},

src/node/blockstorage.h

@@ -235,7 +235,7 @@ private:
 
     const bool m_prune_mode;
 
-    const std::vector<std::byte> m_xor_key;
+    const Obfuscation m_obfuscation;
 
     /** Dirty block index entries. */
     std::set<CBlockIndex*> m_dirty_blockindex;

src/node/mempool_persist.cpp

@@ -60,12 +60,11 @@ bool LoadMempool(CTxMemPool& pool, const fs::path& load_path, Chainstate& active
         file >> version;
 
         if (version == MEMPOOL_DUMP_VERSION_NO_XOR_KEY) {
-            std::vector<std::byte> xor_key;
-            file.SetXor(xor_key);
+            file.SetObfuscation(0);
         } else if (version == MEMPOOL_DUMP_VERSION) {
-            std::vector<std::byte> xor_key;
-            file >> xor_key;
-            file.SetXor(xor_key);
+            Obfuscation obfuscation{0};
+            file >> obfuscation;
+            file.SetObfuscation(obfuscation);
         } else {
             return false;
         }
@@ -181,13 +180,11 @@ bool DumpMempool(const CTxMemPool& pool, const fs::path& dump_path, FopenFn mock
         file << version;
 
         if (!pool.m_opts.persist_v1_dat) {
-            std::vector<std::byte> xor_key(8);
-            FastRandomContext{}.fillrand(xor_key);
-            file << xor_key;
-            file.SetXor(xor_key);
+            const Obfuscation obfuscation{FastRandomContext{}.rand64()};
+            file << obfuscation;
+            file.SetObfuscation(obfuscation);
         } else {
-            std::vector<std::byte> xor_key(8);
-            file.SetXor(xor_key);
+            file.SetObfuscation(0);
         }
 
         uint64_t mempool_transactions_to_write(vinfo.size());

src/obfuscation.h

@@ -0,0 +1,85 @@
+// Copyright (c) 2009-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_OBFUSCATION_H
+#define BITCOIN_OBFUSCATION_H
+
+#include <array>
+#include <cassert>
+#include <cstdint>
+#include <random>
+#include <span.h>
+#include <util/check.h>
+#include <cstring>
+#include <climits>
+#include <serialize.h>
+
+class Obfuscation
+{
+public:
+    static constexpr size_t SIZE_BYTES{sizeof(uint64_t)};
+
+private:
+    std::array<uint64_t, SIZE_BYTES> rotations; // Cached key rotations
+    void SetRotations(const uint64_t key)
+    {
+        for (size_t i{0}; i < SIZE_BYTES; ++i) {
+            size_t key_rotation_bits{CHAR_BIT * i};
+            if constexpr (std::endian::native == std::endian::big) key_rotation_bits *= -1;
+            rotations[i] = std::rotr(key, key_rotation_bits);
+        }
+    }
+
+    static uint64_t ToUint64(const std::span<const std::byte, SIZE_BYTES> key_span)
+    {
+        uint64_t key{};
+        std::memcpy(&key, key_span.data(), SIZE_BYTES);
+        return key;
+    }
+
+    static void Xor(std::span<std::byte> write, const uint64_t key, const size_t size)
+    {
+        assert(size <= write.size());
+        uint64_t raw{};
+        std::memcpy(&raw, write.data(), size);
+        raw ^= key;
+        std::memcpy(write.data(), &raw, size);
+    }
+
+public:
+    Obfuscation(const uint64_t key) { SetRotations(key); }
+    Obfuscation(const std::span<const std::byte, SIZE_BYTES> key_span) : Obfuscation(ToUint64(key_span)) {}
+    Obfuscation(const std::vector<uint8_t>& key_vec) : Obfuscation(MakeByteSpan(key_vec).first<SIZE_BYTES>()) {}
+    Obfuscation(const std::vector<std::byte>& key_vec) : Obfuscation(std::span(key_vec).first<SIZE_BYTES>()) {}
+
+    uint64_t Key() const { return rotations[0]; }
+    operator bool() const { return Key() != 0; }
+    void operator()(std::span<std::byte> write, const size_t key_offset_bytes = 0) const
+    {
+        if (!*this) return;
+        const uint64_t rot_key{rotations[key_offset_bytes % SIZE_BYTES]}; // Continue obfuscation from where we left off
+        for (; write.size() >= SIZE_BYTES; write = write.subspan(SIZE_BYTES)) { // Process multiple bytes at a time
+            Xor(write, rot_key, SIZE_BYTES);
+        }
+        Xor(write, rot_key, write.size());
+    }
+
+    template <typename Stream>
+    void Serialize(Stream& s) const
+    {
+        std::vector<std::byte> bytes(SIZE_BYTES);
+        std::memcpy(bytes.data(), &rotations[0], SIZE_BYTES);
+        s << bytes;
+    }
+
+    template <typename Stream>
+    void Unserialize(Stream& s)
+    {
+        std::vector<std::byte> bytes(SIZE_BYTES);
+        s >> bytes;
+        SetRotations(ToUint64(MakeByteSpan(bytes).first<SIZE_BYTES>()));
+    }
+};
+
+#endif // BITCOIN_OBFUSCATION_H

src/streams.cpp

@@ -9,8 +9,7 @@
 
 #include <array>
 
-AutoFile::AutoFile(std::FILE* file, std::vector<std::byte> data_xor)
-    : m_file{file}, m_xor{std::move(data_xor)}
+AutoFile::AutoFile(std::FILE* file, const Obfuscation& obfuscation) : m_file{file}, m_obfuscation{obfuscation}
 {
     if (!IsNull()) {
         auto pos{std::ftell(m_file)};
@@ -21,12 +20,12 @@ AutoFile::AutoFile(std::FILE* file, std::vector<std::byte> data_xor)
 std::size_t AutoFile::detail_fread(std::span<std::byte> dst)
 {
     if (!m_file) throw std::ios_base::failure("AutoFile::read: file handle is nullptr");
-    size_t ret = std::fread(dst.data(), 1, dst.size(), m_file);
-    if (!m_xor.empty()) {
-        if (!m_position.has_value()) throw std::ios_base::failure("AutoFile::read: position unknown");
-        util::Xor(dst.subspan(0, ret), m_xor, *m_position);
+    const size_t ret = std::fread(dst.data(), 1, dst.size(), m_file);
+    if (m_obfuscation) {
+        if (!m_position) throw std::ios_base::failure("AutoFile::read: position unknown");
+        m_obfuscation(dst, *m_position);
     }
-    if (m_position.has_value()) *m_position += ret;
+    if (m_position) *m_position += ret;
     return ret;
 }
 
@@ -81,7 +80,7 @@ void AutoFile::ignore(size_t nSize)
 void AutoFile::write(std::span<const std::byte> src)
 {
     if (!m_file) throw std::ios_base::failure("AutoFile::write: file handle is nullptr");
-    if (m_xor.empty()) {
+    if (!m_obfuscation) {
         if (std::fwrite(src.data(), 1, src.size(), m_file) != src.size()) {
             throw std::ios_base::failure("AutoFile::write: write failed");
         }
@@ -100,9 +99,9 @@ void AutoFile::write(std::span<const std::byte> src)
 void AutoFile::write_buffer(std::span<std::byte> src)
 {
     if (!m_file) throw std::ios_base::failure("AutoFile::write_buffer: file handle is nullptr");
-    if (m_xor.size()) {
+    if (m_obfuscation) {
         if (!m_position) throw std::ios_base::failure("AutoFile::write_buffer: obfuscation position unknown");
-        util::Xor(src, m_xor, *m_position); // obfuscate in-place
+        m_obfuscation(src, *m_position); // obfuscate in-place
     }
     if (std::fwrite(src.data(), 1, src.size(), m_file) != src.size()) {
         throw std::ios_base::failure("AutoFile::write_buffer: write failed");

src/streams.h

@@ -6,6 +6,7 @@
 #ifndef BITCOIN_STREAMS_H
 #define BITCOIN_STREAMS_H
 
+#include <obfuscation.h>
 #include <serialize.h>
 #include <span.h>
 #include <support/allocators/zeroafterfree.h>
@@ -21,30 +22,8 @@
 #include <stdint.h>
 #include <string.h>
 #include <string>
-#include <utility>
 #include <vector>
 
-namespace util {
-inline void Xor(std::span<std::byte> write, std::span<const std::byte> key, size_t key_offset = 0)
-{
-    if (key.size() == 0) {
-        return;
-    }
-    key_offset %= key.size();
-
-    for (size_t i = 0, j = key_offset; i != write.size(); i++) {
-        write[i] ^= key[j++];
-
-        // This potentially acts on very many bytes of data, so it's
-        // important that we calculate `j`, i.e. the `key` index in this
-        // way instead of doing a %, which would effectively be a division
-        // for each byte Xor'd -- much slower than need be.
-        if (j == key.size())
-            j = 0;
-    }
-}
-} // namespace util
-
 /* Minimal stream for overwriting and/or appending to an existing byte vector
  *
  * The referenced vector will grow as necessary
@@ -261,21 +240,16 @@ public:
         return (*this);
     }
 
-    template<typename T>
+    template <typename T>
     DataStream& operator>>(T&& obj)
     {
         ::Unserialize(*this, obj);
         return (*this);
     }
 
-    /**
-     * XOR the contents of this stream with a certain key.
-     *
-     * @param[in] key    The key used to XOR the data in this stream.
-     */
-    void Xor(const std::vector<unsigned char>& key)
+    void Obfuscate(const Obfuscation& obfuscation)
     {
-        util::Xor(MakeWritableByteSpan(*this), MakeByteSpan(key));
+        if (obfuscation) obfuscation(MakeWritableByteSpan(*this));
     }
 
     /** Compute total memory usage of this object (own memory + any dynamic memory). */
@@ -392,11 +366,11 @@ class AutoFile
 {
 protected:
     std::FILE* m_file;
-    std::vector<std::byte> m_xor;
+    Obfuscation m_obfuscation;
     std::optional<int64_t> m_position;
 
 public:
-    explicit AutoFile(std::FILE* file, std::vector<std::byte> data_xor={});
+    explicit AutoFile(std::FILE* file, const Obfuscation& obfuscation = 0);
 
     ~AutoFile() { fclose(); }
 
@@ -428,7 +402,7 @@ public:
     bool IsNull() const { return m_file == nullptr; }
 
     /** Continue with a different XOR key */
-    void SetXor(std::vector<std::byte> data_xor) { m_xor = data_xor; }
+    void SetObfuscation(const Obfuscation& obfuscation) { m_obfuscation = obfuscation; }
 
     /** Implementation detail, only used internally. */
     std::size_t detail_fread(std::span<std::byte> dst);

src/test/dbwrapper_tests.cpp

@@ -14,16 +14,6 @@
 
 using util::ToString;
 
-// Test if a string consists entirely of null characters
-static bool is_null_key(const std::vector<unsigned char>& key) {
-    bool isnull = true;
-
-    for (unsigned int i = 0; i < key.size(); i++)
-        isnull &= (key[i] == '\x00');
-
-    return isnull;
-}
-
 BOOST_FIXTURE_TEST_SUITE(dbwrapper_tests, BasicTestingSetup)
 
 BOOST_AUTO_TEST_CASE(dbwrapper)
@@ -37,7 +27,7 @@ BOOST_AUTO_TEST_CASE(dbwrapper)
         uint256 res;
 
         // Ensure that we're doing real obfuscation when obfuscate=true
-        BOOST_CHECK(obfuscate != is_null_key(dbwrapper_private::GetObfuscateKey(dbw)));
+        BOOST_CHECK(obfuscate == dbwrapper_private::GetObfuscation(dbw));
 
         BOOST_CHECK(dbw.Write(key, in));
         BOOST_CHECK(dbw.Read(key, res));
@@ -57,7 +47,7 @@ BOOST_AUTO_TEST_CASE(dbwrapper_basic_data)
         bool res_bool;
 
         // Ensure that we're doing real obfuscation when obfuscate=true
-        BOOST_CHECK(obfuscate != is_null_key(dbwrapper_private::GetObfuscateKey(dbw)));
+        BOOST_CHECK(obfuscate == dbwrapper_private::GetObfuscation(dbw));
 
         //Simulate block raw data - "b + block hash"
         std::string key_block = "b" + m_rng.rand256().ToString();
@@ -232,7 +222,7 @@ BOOST_AUTO_TEST_CASE(existing_data_no_obfuscate)
     BOOST_CHECK_EQUAL(res2.ToString(), in.ToString());
 
     BOOST_CHECK(!odbw.IsEmpty()); // There should be existing data
-    BOOST_CHECK(is_null_key(dbwrapper_private::GetObfuscateKey(odbw))); // The key should be an empty string
+    BOOST_CHECK(!dbwrapper_private::GetObfuscation(odbw));
 
     uint256 in2 = m_rng.rand256();
     uint256 res3;
@@ -269,7 +259,7 @@ BOOST_AUTO_TEST_CASE(existing_data_reindex)
     // Check that the key/val we wrote with unobfuscated wrapper doesn't exist
     uint256 res2;
     BOOST_CHECK(!odbw.Read(key, res2));
-    BOOST_CHECK(!is_null_key(dbwrapper_private::GetObfuscateKey(odbw)));
+    BOOST_CHECK(dbwrapper_private::GetObfuscation(odbw));
 
     uint256 in2 = m_rng.rand256();
     uint256 res3;

src/test/fuzz/autofile.cpp

@@ -20,7 +20,7 @@ FUZZ_TARGET(autofile)
     FuzzedFileProvider fuzzed_file_provider{fuzzed_data_provider};
     AutoFile auto_file{
         fuzzed_file_provider.open(),
-        ConsumeRandomLengthByteVector<std::byte>(fuzzed_data_provider),
+        fuzzed_data_provider.ConsumeIntegral<uint64_t>()
     };
     LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 100)
     {

src/test/fuzz/buffered_file.cpp

@@ -22,7 +22,7 @@ FUZZ_TARGET(buffered_file)
     std::optional<BufferedFile> opt_buffered_file;
     AutoFile fuzzed_file{
         fuzzed_file_provider.open(),
-        ConsumeRandomLengthByteVector<std::byte>(fuzzed_data_provider),
+        fuzzed_data_provider.ConsumeIntegral<uint64_t>()
     };
     try {
         auto n_buf_size = fuzzed_data_provider.ConsumeIntegralInRange<uint64_t>(0, 4096);

src/test/streams_tests.cpp

@@ -20,10 +20,10 @@ BOOST_FIXTURE_TEST_SUITE(streams_tests, BasicTestingSetup)
 // Test that obfuscation can be properly reversed even with random chunk sizes.
 BOOST_AUTO_TEST_CASE(xor_roundtrip_random_chunks)
 {
-    auto apply_random_xor_chunks{[&](std::span<std::byte> write, const std::span<std::byte> key) {
+    auto apply_random_xor_chunks{[&](std::span<std::byte> write, const Obfuscation& obfuscation) {
         for (size_t offset{0}; offset < write.size();) {
             const size_t chunk_size{1 + m_rng.randrange(write.size() - offset)};
-            util::Xor(write.subspan(offset, chunk_size), key, offset);
+            obfuscation(write.subspan(offset, chunk_size), offset);
             offset += chunk_size;
         }
     }};
@@ -33,16 +33,15 @@ BOOST_AUTO_TEST_CASE(xor_roundtrip_random_chunks)
         const std::vector original{m_rng.randbytes<std::byte>(write_size)};
         std::vector roundtrip{original};
 
-        std::vector key_bytes{m_rng.randbytes<std::byte>(sizeof(uint64_t))};
-        uint64_t xor_key;
-        std::memcpy(&xor_key, key_bytes.data(), sizeof(xor_key));
-        apply_random_xor_chunks(roundtrip, key_bytes);
+        const auto key_bytes{m_rng.randbytes<std::byte>(Obfuscation::SIZE_BYTES)};
+        const Obfuscation obfuscation{key_bytes};
+        apply_random_xor_chunks(roundtrip, obfuscation);
 
         // Verify intermediate state is different from original (unless key is zero)
-        const bool all_zero = (xor_key == 0) || (HexStr(key_bytes).find_first_not_of('0') >= write_size * 2);
+        const bool all_zero = !obfuscation || (HexStr(key_bytes).find_first_not_of('0') >= write_size * 2);
         BOOST_CHECK_EQUAL(original != roundtrip, !all_zero);
 
-        apply_random_xor_chunks(roundtrip, key_bytes);
+        apply_random_xor_chunks(roundtrip, obfuscation);
         BOOST_CHECK(original == roundtrip);
     }
 }
@@ -61,20 +60,69 @@ BOOST_AUTO_TEST_CASE(xor_bytes_reference)
         const size_t write_size{1 + m_rng.randrange(100U)};
         const size_t key_offset{m_rng.randrange(3 * 8U)}; // Should wrap around
 
-        std::vector key_bytes{m_rng.randbytes<std::byte>(sizeof(uint64_t))};
-        uint64_t xor_key;
-        std::memcpy(&xor_key, key_bytes.data(), sizeof(xor_key));
-
+        const auto key_bytes{m_rng.randbytes<std::byte>(Obfuscation::SIZE_BYTES)};
+        const Obfuscation obfuscation{key_bytes};
         std::vector expected{m_rng.randbytes<std::byte>(write_size)};
         std::vector actual{expected};
 
         expected_xor(expected, key_bytes, key_offset);
-        util::Xor(actual, key_bytes, key_offset);
+        obfuscation(actual, key_offset);
 
         BOOST_CHECK_EQUAL_COLLECTIONS(expected.begin(), expected.end(), actual.begin(), actual.end());
     }
 }
 
+
+BOOST_AUTO_TEST_CASE(obfuscation_constructors)
+{
+    constexpr uint64_t test_key = 0x0123456789ABCDEF;
+
+    // Direct uint64_t constructor
+    const Obfuscation obf1{test_key};
+    BOOST_CHECK_EQUAL(obf1.Key(), test_key);
+
+    // std::span constructor
+    std::array<std::byte, Obfuscation::SIZE_BYTES> key_bytes{};
+    std::memcpy(key_bytes.data(), &test_key, Obfuscation::SIZE_BYTES);
+    const Obfuscation obf2{std::span{key_bytes}};
+    BOOST_CHECK_EQUAL(obf2.Key(), test_key);
+
+    // std::vector<uint8_t> constructor
+    std::vector<uint8_t> uint8_key(Obfuscation::SIZE_BYTES);
+    std::memcpy(uint8_key.data(), &test_key, uint8_key.size());
+    const Obfuscation obf4{uint8_key};
+    BOOST_CHECK_EQUAL(obf4.Key(), test_key);
+
+    // std::vector<std::byte> constructor
+    std::vector<std::byte> byte_vector_key(Obfuscation::SIZE_BYTES);
+    std::memcpy(byte_vector_key.data(), &test_key, byte_vector_key.size());
+    const Obfuscation obf5{byte_vector_key};
+    BOOST_CHECK_EQUAL(obf5.Key(), test_key);
+}
+
+BOOST_AUTO_TEST_CASE(obfuscation_serialize)
+{
+    const Obfuscation original{0xDEADBEEF};
+
+    // Serialize
+    DataStream ds;
+    ds << original;
+
+    BOOST_CHECK_EQUAL(ds.size(), 1 + Obfuscation::SIZE_BYTES); // serialized as a vector
+
+    // Deserialize
+    Obfuscation recovered{0};
+    ds >> recovered;
+
+    BOOST_CHECK_EQUAL(recovered.Key(), original.Key());
+}
+
+BOOST_AUTO_TEST_CASE(obfuscation_empty)
+{
+    const Obfuscation null_obf{0};
+    BOOST_CHECK(!null_obf);
+}
+
 BOOST_AUTO_TEST_CASE(xor_file)
 {
     fs::path xor_path{m_args.GetDataDirBase() / "test_xor.bin"};
@@ -99,7 +147,7 @@ BOOST_AUTO_TEST_CASE(xor_file)
 #else
         const char* mode = "wbx";
 #endif
-        AutoFile xor_file{raw_file(mode), key_bytes};
+        AutoFile xor_file{raw_file(mode), xor_key};
         xor_file << test1 << test2;
     }
     {
@@ -112,7 +160,7 @@ BOOST_AUTO_TEST_CASE(xor_file)
         BOOST_CHECK_EXCEPTION(non_xor_file.ignore(1), std::ios_base::failure, HasReason{"AutoFile::ignore: end of file"});
     }
     {
-        AutoFile xor_file{raw_file("rb"), key_bytes};
+        AutoFile xor_file{raw_file("rb"), xor_key};
         std::vector<std::byte> read1, read2;
         xor_file >> read1 >> read2;
         BOOST_CHECK_EQUAL(HexStr(read1), HexStr(test1));
@@ -121,7 +169,7 @@ BOOST_AUTO_TEST_CASE(xor_file)
         BOOST_CHECK_EXCEPTION(xor_file >> std::byte{}, std::ios_base::failure, HasReason{"AutoFile::read: end of file"});
     }
     {
-        AutoFile xor_file{raw_file("rb"), key_bytes};
+        AutoFile xor_file{raw_file("rb"), xor_key};
         std::vector<std::byte> read2;
         // Check that ignore works
         xor_file.ignore(4);
@@ -289,7 +337,7 @@ BOOST_AUTO_TEST_CASE(streams_serializedata_xor)
     // Degenerate case
     {
         DataStream ds{in};
-        ds.Xor("0000000000000000"_hex_v_u8);
+        Obfuscation{0}(ds);
         BOOST_CHECK_EQUAL(""s, ds.str());
     }
 
@@ -297,12 +345,10 @@ BOOST_AUTO_TEST_CASE(streams_serializedata_xor)
     in.push_back(std::byte{0xf0});
 
     {
-        const auto key_bytes{"ffffffffffffffff"_hex_v};
-        uint64_t xor_key;
-        std::memcpy(&xor_key, key_bytes.data(), sizeof(xor_key));
+        const Obfuscation obfuscation{"ffffffffffffffff"_hex_v};
 
         DataStream ds{in};
-        ds.Xor("ffffffffffffffff"_hex_v_u8);
+        obfuscation(ds);
         BOOST_CHECK_EQUAL("\xf0\x0f"s, ds.str());
     }
 
@@ -311,10 +357,10 @@ BOOST_AUTO_TEST_CASE(streams_serializedata_xor)
     in.push_back(std::byte{0x0f});
 
     {
-        const auto key_bytes{"ff0fff0fff0fff0f"_hex_v};
+        const Obfuscation obfuscation{"ff0fff0fff0fff0f"_hex_v};
 
         DataStream ds{in};
-        ds.Xor("ff0fff0fff0fff0f"_hex_v_u8);
+        obfuscation(ds);
         BOOST_CHECK_EQUAL("\x0f\x00"s, ds.str());
     }
 }