Merge #19326: Simplify hash.h interface using Spans

77c507358bda9bd6c496f33e0f4418c0603bb08d Make Hash[160] consume range-like objects (Pieter Wuille)
02c4cc5c5ddf61f98ee366a4bea8abc26de492bd Make CHash256/CHash160 output to Span (Pieter Wuille)
0ef97b1b103231db54e04a64bbdb5dcc3f34f482 Make MurmurHash3 consume Spans (Pieter Wuille)
e549bf8a9afae42fcda805e216a1cde62df195a6 Make CHash256 and CHash160 consume Spans (Pieter Wuille)
2a2182c387f607cd8284f33890bd285a81077b7f Make script/standard's BaseHash Span-convertible (Pieter Wuille)
e63dcc3a6752e7d406e7a650c2d6c2e95cd39aab Add MakeUCharSpan, to help constructing Span<[const] unsigned char> (Pieter Wuille)
567825049fb0e47e698dcaad9caa65693a6b42d3 Make uint256 Span-convertible by adding ::data() (Pieter Wuille)
131a2f0337f5c396739a47b60bb856ed84ec8937 scripted-diff: rename base_blob::data to m_data (Pieter Wuille)

Pull request description:

  This makes use of the implicit constructions and conversions to Span introduced in #18468 to simplify the hash.h interface:

  * All functions that take a pointer and a length are changed to take a Span instead.
  * The Hash() and Hash160() functions are changed to take in "range" objects instead of begin/end iterators.

ACKs for top commit:
  laanwj:
    re-ACK 77c507358bda9bd6c496f33e0f4418c0603bb08d
  jonatack:
    Code review re-ACK 77c5073 per `git range-diff 14ceddd 49fc016 77c5073`

Tree-SHA512: 9ec929891b1ddcf30eb14b946ee1bf142eca1442b9de0067ad6a3c181e0c7ea0c99c0e291e7f6e7a18bd7bdf78fe94ee3d5de66e167401674caf91e026269771

31 files changed, 117 insertions, 120 deletions

diff --git a/src/base58.cpp b/src/base58.cpp
index 6a9e21ffc2..9b2946e7a9 100644
--- a/src/base58.cpp
+++ b/src/base58.cpp
@@ -141,7 +141,7 @@ std::string EncodeBase58Check(const std::vector<unsigned char>& vchIn)
 {
     // add 4-byte hash check to the end
     std::vector<unsigned char> vch(vchIn);
-    uint256 hash = Hash(vch.begin(), vch.end());
+    uint256 hash = Hash(vch);
     vch.insert(vch.end(), (unsigned char*)&hash, (unsigned char*)&hash + 4);
     return EncodeBase58(vch);
 }
@@ -154,7 +154,7 @@ bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet, int
         return false;
     }
     // re-calculate the checksum, ensure it matches the included 4-byte checksum
-    uint256 hash = Hash(vchRet.begin(), vchRet.end() - 4);
+    uint256 hash = Hash(MakeSpan(vchRet).first(vchRet.size() - 4));
     if (memcmp(&hash, &vchRet[vchRet.size() - 4], 4) != 0) {
         vchRet.clear();
         return false;
diff --git a/src/bench/chacha_poly_aead.cpp b/src/bench/chacha_poly_aead.cpp
index 30d7851b7f..3b1d3e697a 100644
--- a/src/bench/chacha_poly_aead.cpp
+++ b/src/bench/chacha_poly_aead.cpp
@@ -93,7 +93,7 @@ static void HASH(benchmark::Bench& bench, size_t buffersize)
     uint8_t hash[CHash256::OUTPUT_SIZE];
     std::vector<uint8_t> in(buffersize,0);
     bench.batch(in.size()).unit("byte").run([&] {
-        CHash256().Write(in.data(), in.size()).Finalize(hash);
+        CHash256().Write(in).Finalize(hash);
     });
 }
 
diff --git a/src/bench/verify_script.cpp b/src/bench/verify_script.cpp
index c489bae4f6..9af0b502eb 100644
--- a/src/bench/verify_script.cpp
+++ b/src/bench/verify_script.cpp
@@ -34,7 +34,7 @@ static void VerifyScriptBench(benchmark::Bench& bench)
     key.Set(vchKey.begin(), vchKey.end(), false);
     CPubKey pubkey = key.GetPubKey();
     uint160 pubkeyHash;
-    CHash160().Write(pubkey.begin(), pubkey.size()).Finalize(pubkeyHash.begin());
+    CHash160().Write(pubkey).Finalize(pubkeyHash);
 
     // Script.
     CScript scriptPubKey = CScript() << witnessversion << ToByteVector(pubkeyHash);
diff --git a/src/blockfilter.cpp b/src/blockfilter.cpp
index 5f5bed5bda..9a6fb4abd0 100644
--- a/src/blockfilter.cpp
+++ b/src/blockfilter.cpp
@@ -291,7 +291,7 @@ uint256 BlockFilter::GetHash() const
     const std::vector<unsigned char>& data = GetEncodedFilter();
 
     uint256 result;
-    CHash256().Write(data.data(), data.size()).Finalize(result.begin());
+    CHash256().Write(data).Finalize(result);
     return result;
 }
 
@@ -301,8 +301,8 @@ uint256 BlockFilter::ComputeHeader(const uint256& prev_header) const
 
     uint256 result;
     CHash256()
-        .Write(filter_hash.begin(), filter_hash.size())
-        .Write(prev_header.begin(), prev_header.size())
-        .Finalize(result.begin());
+        .Write(filter_hash)
+        .Write(prev_header)
+        .Finalize(result);
     return result;
 }
diff --git a/src/hash.cpp b/src/hash.cpp
index 26150e5ca8..4c09f5f646 100644
--- a/src/hash.cpp
+++ b/src/hash.cpp
@@ -12,7 +12,7 @@ inline uint32_t ROTL32(uint32_t x, int8_t r)
     return (x << r) | (x >> (32 - r));
 }
 
-unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char>& vDataToHash)
+unsigned int MurmurHash3(unsigned int nHashSeed, Span<const unsigned char> vDataToHash)
 {
     // The following is MurmurHash3 (x86_32), see http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp
     uint32_t h1 = nHashSeed;
diff --git a/src/hash.h b/src/hash.h
index c295568a3e..71806483ff 100644
--- a/src/hash.h
+++ b/src/hash.h
@@ -25,14 +25,15 @@ private:
 public:
     static const size_t OUTPUT_SIZE = CSHA256::OUTPUT_SIZE;
 
-    void Finalize(unsigned char hash[OUTPUT_SIZE]) {
+    void Finalize(Span<unsigned char> output) {
+        assert(output.size() == OUTPUT_SIZE);
         unsigned char buf[CSHA256::OUTPUT_SIZE];
         sha.Finalize(buf);
-        sha.Reset().Write(buf, CSHA256::OUTPUT_SIZE).Finalize(hash);
+        sha.Reset().Write(buf, CSHA256::OUTPUT_SIZE).Finalize(output.data());
     }
 
-    CHash256& Write(const unsigned char *data, size_t len) {
-        sha.Write(data, len);
+    CHash256& Write(Span<const unsigned char> input) {
+        sha.Write(input.data(), input.size());
         return *this;
     }
 
@@ -49,14 +50,15 @@ private:
 public:
     static const size_t OUTPUT_SIZE = CRIPEMD160::OUTPUT_SIZE;
 
-    void Finalize(unsigned char hash[OUTPUT_SIZE]) {
+    void Finalize(Span<unsigned char> output) {
+        assert(output.size() == OUTPUT_SIZE);
         unsigned char buf[CSHA256::OUTPUT_SIZE];
         sha.Finalize(buf);
-        CRIPEMD160().Write(buf, CSHA256::OUTPUT_SIZE).Finalize(hash);
+        CRIPEMD160().Write(buf, CSHA256::OUTPUT_SIZE).Finalize(output.data());
     }
 
-    CHash160& Write(const unsigned char *data, size_t len) {
-        sha.Write(data, len);
+    CHash160& Write(Span<const unsigned char> input) {
+        sha.Write(input.data(), input.size());
         return *this;
     }
 
@@ -67,52 +69,31 @@ public:
 };
 
 /** Compute the 256-bit hash of an object. */
-template<typename T1>
-inline uint256 Hash(const T1 pbegin, const T1 pend)
+template<typename T>
+inline uint256 Hash(const T& in1)
 {
-    static const unsigned char pblank[1] = {};
     uint256 result;
-    CHash256().Write(pbegin == pend ? pblank : (const unsigned char*)&pbegin[0], (pend - pbegin) * sizeof(pbegin[0]))
-              .Finalize((unsigned char*)&result);
+    CHash256().Write(MakeUCharSpan(in1)).Finalize(result);
     return result;
 }
 
 /** Compute the 256-bit hash of the concatenation of two objects. */
 template<typename T1, typename T2>
-inline uint256 Hash(const T1 p1begin, const T1 p1end,
-                    const T2 p2begin, const T2 p2end) {
-    static const unsigned char pblank[1] = {};
+inline uint256 Hash(const T1& in1, const T2& in2) {
     uint256 result;
-    CHash256().Write(p1begin == p1end ? pblank : (const unsigned char*)&p1begin[0], (p1end - p1begin) * sizeof(p1begin[0]))
-              .Write(p2begin == p2end ? pblank : (const unsigned char*)&p2begin[0], (p2end - p2begin) * sizeof(p2begin[0]))
-              .Finalize((unsigned char*)&result);
+    CHash256().Write(MakeUCharSpan(in1)).Write(MakeUCharSpan(in2)).Finalize(result);
     return result;
 }
 
 /** Compute the 160-bit hash an object. */
 template<typename T1>
-inline uint160 Hash160(const T1 pbegin, const T1 pend)
+inline uint160 Hash160(const T1& in1)
 {
-    static unsigned char pblank[1] = {};
     uint160 result;
-    CHash160().Write(pbegin == pend ? pblank : (const unsigned char*)&pbegin[0], (pend - pbegin) * sizeof(pbegin[0]))
-              .Finalize((unsigned char*)&result);
+    CHash160().Write(MakeUCharSpan(in1)).Finalize(result);
     return result;
 }
 
-/** Compute the 160-bit hash of a vector. */
-inline uint160 Hash160(const std::vector<unsigned char>& vch)
-{
-    return Hash160(vch.begin(), vch.end());
-}
-
-/** Compute the 160-bit hash of a vector. */
-template<unsigned int N>
-inline uint160 Hash160(const prevector<N, unsigned char>& vch)
-{
-    return Hash160(vch.begin(), vch.end());
-}
-
 /** A writer stream (for serialization) that computes a 256-bit hash. */
 class CHashWriter
 {
@@ -129,13 +110,13 @@ public:
     int GetVersion() const { return nVersion; }
 
     void write(const char *pch, size_t size) {
-        ctx.Write((const unsigned char*)pch, size);
+        ctx.Write({(const unsigned char*)pch, size});
     }
 
     // invalidates the object
     uint256 GetHash() {
         uint256 result;
-        ctx.Finalize((unsigned char*)&result);
+        ctx.Finalize(result);
         return result;
     }
 
@@ -200,7 +181,7 @@ uint256 SerializeHash(const T& obj, int nType=SER_GETHASH, int nVersion=PROTOCOL
     return ss.GetHash();
 }
 
-unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char>& vDataToHash);
+unsigned int MurmurHash3(unsigned int nHashSeed, Span<const unsigned char> vDataToHash);
 
 void BIP32Hash(const ChainCode &chainCode, unsigned int nChild, unsigned char header, const unsigned char data[32], unsigned char output[64]);
 
diff --git a/src/key.cpp b/src/key.cpp
index 7eecc6e083..4ed74a39b1 100644
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -237,7 +237,7 @@ bool CKey::VerifyPubKey(const CPubKey& pubkey) const {
     std::string str = "Bitcoin key verification\n";
     GetRandBytes(rnd, sizeof(rnd));
     uint256 hash;
-    CHash256().Write((unsigned char*)str.data(), str.size()).Write(rnd, sizeof(rnd)).Finalize(hash.begin());
+    CHash256().Write(MakeUCharSpan(str)).Write(rnd).Finalize(hash);
     std::vector<unsigned char> vchSig;
     Sign(hash, vchSig);
     return pubkey.Verify(hash, vchSig);
diff --git a/src/merkleblock.cpp b/src/merkleblock.cpp
index 8072b12119..b571d463c9 100644
--- a/src/merkleblock.cpp
+++ b/src/merkleblock.cpp
@@ -70,7 +70,7 @@ uint256 CPartialMerkleTree::CalcHash(int height, unsigned int pos, const std::ve
         else
             right = left;
         // combine subhashes
-        return Hash(left.begin(), left.end(), right.begin(), right.end());
+        return Hash(left, right);
     }
 }
 
@@ -126,7 +126,7 @@ uint256 CPartialMerkleTree::TraverseAndExtract(int height, unsigned int pos, uns
             right = left;
         }
         // and combine them before returning
-        return Hash(left.begin(), left.end(), right.begin(), right.end());
+        return Hash(left, right);
     }
 }
 
diff --git a/src/net.cpp b/src/net.cpp
index bf29d928a1..9c72c62df9 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -685,7 +685,7 @@ int V1TransportDeserializer::readData(const char *pch, unsigned int nBytes)
         vRecv.resize(std::min(hdr.nMessageSize, nDataPos + nCopy + 256 * 1024));
     }
 
-    hasher.Write((const unsigned char*)pch, nCopy);
+    hasher.Write({(const unsigned char*)pch, nCopy});
     memcpy(&vRecv[nDataPos], pch, nCopy);
     nDataPos += nCopy;
 
@@ -696,7 +696,7 @@ const uint256& V1TransportDeserializer::GetMessageHash() const
 {
     assert(Complete());
     if (data_hash.IsNull())
-        hasher.Finalize(data_hash.begin());
+        hasher.Finalize(data_hash);
     return data_hash;
 }
 
@@ -736,7 +736,7 @@ CNetMessage V1TransportDeserializer::GetMessage(const CMessageHeader::MessageSta
 
 void V1TransportSerializer::prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) {
     // create dbl-sha256 checksum
-    uint256 hash = Hash(msg.data.begin(), msg.data.end());
+    uint256 hash = Hash(msg.data);
 
     // create header
     CMessageHeader hdr(Params().MessageStart(), msg.m_type.c_str(), msg.data.size());
diff --git a/src/netaddress.cpp b/src/netaddress.cpp
index 0874b8dcea..d29aed6c8b 100644
--- a/src/netaddress.cpp
+++ b/src/netaddress.cpp
@@ -553,7 +553,7 @@ std::vector<unsigned char> CNetAddr::GetGroup(const std::vector<bool> &asmap) co
 
 uint64_t CNetAddr::GetHash() const
 {
-    uint256 hash = Hash(&ip[0], &ip[16]);
+    uint256 hash = Hash(ip);
     uint64_t nRet;
     memcpy(&nRet, &hash, sizeof(nRet));
     return nRet;
diff --git a/src/pubkey.h b/src/pubkey.h
index 4c28af4a4d..fcbc7e8416 100644
--- a/src/pubkey.h
+++ b/src/pubkey.h
@@ -157,13 +157,13 @@ public:
     //! Get the KeyID of this public key (hash of its serialization)
     CKeyID GetID() const
     {
-        return CKeyID(Hash160(vch, vch + size()));
+        return CKeyID(Hash160(MakeSpan(vch).first(size())));
     }
 
     //! Get the 256-bit hash of this public key.
     uint256 GetHash() const
     {
-        return Hash(vch, vch + size());
+        return Hash(MakeSpan(vch).first(size()));
     }
 
     /*
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 70caf6009a..cf856af6e9 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -601,7 +601,7 @@ static UniValue decodescript(const JSONRPCRequest& request)
             UniValue sr(UniValue::VOBJ);
             CScript segwitScr;
             if (which_type == TxoutType::PUBKEY) {
-                segwitScr = GetScriptForDestination(WitnessV0KeyHash(Hash160(solutions_data[0].begin(), solutions_data[0].end())));
+                segwitScr = GetScriptForDestination(WitnessV0KeyHash(Hash160(solutions_data[0])));
             } else if (which_type == TxoutType::PUBKEYHASH) {
                 segwitScr = GetScriptForDestination(WitnessV0KeyHash(uint160{solutions_data[0]}));
             } else {
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 9415bba585..39feb4ccc9 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -986,9 +986,9 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                     else if (opcode == OP_SHA256)
                         CSHA256().Write(vch.data(), vch.size()).Finalize(vchHash.data());
                     else if (opcode == OP_HASH160)
-                        CHash160().Write(vch.data(), vch.size()).Finalize(vchHash.data());
+                        CHash160().Write(vch).Finalize(vchHash);
                     else if (opcode == OP_HASH256)
-                        CHash256().Write(vch.data(), vch.size()).Finalize(vchHash.data());
+                        CHash256().Write(vch).Finalize(vchHash);
                     popstack(stack);
                     stack.push_back(vchHash);
                 }
diff --git a/src/script/standard.cpp b/src/script/standard.cpp
index 1c4990791c..3a4882f280 100644
--- a/src/script/standard.cpp
+++ b/src/script/standard.cpp
@@ -16,10 +16,10 @@ typedef std::vector<unsigned char> valtype;
 bool fAcceptDatacarrier = DEFAULT_ACCEPT_DATACARRIER;
 unsigned nMaxDatacarrierBytes = MAX_OP_RETURN_RELAY;
 
-CScriptID::CScriptID(const CScript& in) : BaseHash(Hash160(in.begin(), in.end())) {}
+CScriptID::CScriptID(const CScript& in) : BaseHash(Hash160(in)) {}
 CScriptID::CScriptID(const ScriptHash& in) : BaseHash(static_cast<uint160>(in)) {}
 
-ScriptHash::ScriptHash(const CScript& in) : BaseHash(Hash160(in.begin(), in.end())) {}
+ScriptHash::ScriptHash(const CScript& in) : BaseHash(Hash160(in)) {}
 ScriptHash::ScriptHash(const CScriptID& in) : BaseHash(static_cast<uint160>(in)) {}
 
 PKHash::PKHash(const CPubKey& pubkey) : BaseHash(pubkey.GetID()) {}
@@ -318,7 +318,7 @@ CScript GetScriptForWitness(const CScript& redeemscript)
     std::vector<std::vector<unsigned char> > vSolutions;
     TxoutType typ = Solver(redeemscript, vSolutions);
     if (typ == TxoutType::PUBKEY) {
-        return GetScriptForDestination(WitnessV0KeyHash(Hash160(vSolutions[0].begin(), vSolutions[0].end())));
+        return GetScriptForDestination(WitnessV0KeyHash(Hash160(vSolutions[0])));
     } else if (typ == TxoutType::PUBKEYHASH) {
         return GetScriptForDestination(WitnessV0KeyHash(uint160{vSolutions[0]}));
     }
diff --git a/src/script/standard.h b/src/script/standard.h
index fd29353886..992e37675f 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -79,6 +79,9 @@ public:
     {
         return m_hash.size();
     }
+
+    unsigned char* data() { return m_hash.data(); }
+    const unsigned char* data() const { return m_hash.data(); }
 };
 
 /** A reference to a CScript: the Hash160 of its serialization (see script.h) */
diff --git a/src/span.h b/src/span.h
index 79f13c9203..4afb383a59 100644
--- a/src/span.h
+++ b/src/span.h
@@ -207,4 +207,16 @@ T& SpanPopBack(Span<T>& span)
     return back;
 }
 
+// Helper functions to safely cast to unsigned char pointers.
+inline unsigned char* UCharCast(char* c) { return (unsigned char*)c; }
+inline unsigned char* UCharCast(unsigned char* c) { return c; }
+inline const unsigned char* UCharCast(const char* c) { return (unsigned char*)c; }
+inline const unsigned char* UCharCast(const unsigned char* c) { return c; }
+
+// Helper function to safely convert a Span to a Span<[const] unsigned char>.
+template <typename T> constexpr auto UCharSpanCast(Span<T> s) -> Span<typename std::remove_pointer<decltype(UCharCast(s.data()))>::type> { return {UCharCast(s.data()), s.size()}; }
+
+/** Like MakeSpan, but for (const) unsigned char member types only. Only works for (un)signed char containers. */
+template <typename V> constexpr auto MakeUCharSpan(V&& v) -> decltype(UCharSpanCast(MakeSpan(std::forward<V>(v)))) { return UCharSpanCast(MakeSpan(std::forward<V>(v))); }
+
 #endif
diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
index f64251fe32..bf5c587774 100644
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -743,7 +743,7 @@ BOOST_AUTO_TEST_CASE(sha256d64)
             in[j] = InsecureRandBits(8);
         }
         for (int j = 0; j < i; ++j) {
-            CHash256().Write(in + 64 * j, 64).Finalize(out1 + 32 * j);
+            CHash256().Write({in + 64 * j, 64}).Finalize({out1 + 32 * j, 32});
         }
         SHA256D64(out2, in, i);
         BOOST_CHECK(memcmp(out1, out2, 32 * i) == 0);
diff --git a/src/test/fuzz/crypto.cpp b/src/test/fuzz/crypto.cpp
index 595cdf9abb..3edcf96495 100644
--- a/src/test/fuzz/crypto.cpp
+++ b/src/test/fuzz/crypto.cpp
@@ -44,8 +44,8 @@ void test_one_input(const std::vector<uint8_t>& buffer)
                 }
             }
 
-            (void)hash160.Write(data.data(), data.size());
-            (void)hash256.Write(data.data(), data.size());
+            (void)hash160.Write(data);
+            (void)hash256.Write(data);
             (void)hmac_sha256.Write(data.data(), data.size());
             (void)hmac_sha512.Write(data.data(), data.size());
             (void)ripemd160.Write(data.data(), data.size());
@@ -54,9 +54,8 @@ void test_one_input(const std::vector<uint8_t>& buffer)
             (void)sha512.Write(data.data(), data.size());
             (void)sip_hasher.Write(data.data(), data.size());
 
-            (void)Hash(data.begin(), data.end());
+            (void)Hash(data);
             (void)Hash160(data);
-            (void)Hash160(data.begin(), data.end());
             (void)sha512.Size();
             break;
         }
@@ -73,12 +72,12 @@ void test_one_input(const std::vector<uint8_t>& buffer)
             switch (fuzzed_data_provider.ConsumeIntegralInRange<int>(0, 8)) {
             case 0: {
                 data.resize(CHash160::OUTPUT_SIZE);
-                hash160.Finalize(data.data());
+                hash160.Finalize(data);
                 break;
             }
             case 1: {
                 data.resize(CHash256::OUTPUT_SIZE);
-                hash256.Finalize(data.data());
+                hash256.Finalize(data);
                 break;
             }
             case 2: {
diff --git a/src/test/fuzz/key.cpp b/src/test/fuzz/key.cpp
index c746374c61..955b954700 100644
--- a/src/test/fuzz/key.cpp
+++ b/src/test/fuzz/key.cpp
@@ -85,7 +85,7 @@ void test_one_input(const std::vector<uint8_t>& buffer)
         assert(negated_key == key);
     }
 
-    const uint256 random_uint256 = Hash(buffer.begin(), buffer.end());
+    const uint256 random_uint256 = Hash(buffer);
 
     {
         CKey child_key;
diff --git a/src/test/key_tests.cpp b/src/test/key_tests.cpp
index fd35537c77..4e4c44266a 100644
--- a/src/test/key_tests.cpp
+++ b/src/test/key_tests.cpp
@@ -77,7 +77,7 @@ BOOST_AUTO_TEST_CASE(key_test1)
     for (int n=0; n<16; n++)
     {
         std::string strMsg = strprintf("Very secret message %i: 11", n);
-        uint256 hashMsg = Hash(strMsg.begin(), strMsg.end());
+        uint256 hashMsg = Hash(strMsg);
 
         // normal signatures
 
@@ -134,7 +134,7 @@ BOOST_AUTO_TEST_CASE(key_test1)
 
     std::vector<unsigned char> detsig, detsigc;
     std::string strMsg = "Very deterministic message";
-    uint256 hashMsg = Hash(strMsg.begin(), strMsg.end());
+    uint256 hashMsg = Hash(strMsg);
     BOOST_CHECK(key1.Sign(hashMsg, detsig));
     BOOST_CHECK(key1C.Sign(hashMsg, detsigc));
     BOOST_CHECK(detsig == detsigc);
@@ -158,7 +158,7 @@ BOOST_AUTO_TEST_CASE(key_signature_tests)
     // When entropy is specified, we should see at least one high R signature within 20 signatures
     CKey key = DecodeSecret(strSecret1);
     std::string msg = "A message to be signed";
-    uint256 msg_hash = Hash(msg.begin(), msg.end());
+    uint256 msg_hash = Hash(msg);
     std::vector<unsigned char> sig;
     bool found = false;
 
@@ -179,7 +179,7 @@ BOOST_AUTO_TEST_CASE(key_signature_tests)
     for (int i = 0; i < 256; ++i) {
         sig.clear();
         std::string msg = "A message to be signed" + ToString(i);
-        msg_hash = Hash(msg.begin(), msg.end());
+        msg_hash = Hash(msg);
         BOOST_CHECK(key.Sign(msg_hash, sig));
         found = sig[3] == 0x20;
         BOOST_CHECK(sig.size() <= 70);
@@ -196,7 +196,7 @@ BOOST_AUTO_TEST_CASE(key_key_negation)
     std::string str = "Bitcoin key verification\n";
     GetRandBytes(rnd, sizeof(rnd));
     uint256 hash;
-    CHash256().Write((unsigned char*)str.data(), str.size()).Write(rnd, sizeof(rnd)).Finalize(hash.begin());
+    CHash256().Write(MakeUCharSpan(str)).Write(rnd).Finalize(hash);
 
     // import the static test key
     CKey key = DecodeSecret(strSecret1C);
diff --git a/src/test/merkle_tests.cpp b/src/test/merkle_tests.cpp
index 03dce552fc..9bc7cc5dab 100644
--- a/src/test/merkle_tests.cpp
+++ b/src/test/merkle_tests.cpp
@@ -13,9 +13,9 @@ static uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vecto
     uint256 hash = leaf;
     for (std::vector<uint256>::const_iterator it = vMerkleBranch.begin(); it != vMerkleBranch.end(); ++it) {
         if (nIndex & 1) {
-            hash = Hash(it->begin(), it->end(), hash.begin(), hash.end());
+            hash = Hash(*it, hash);
         } else {
-            hash = Hash(hash.begin(), hash.end(), it->begin(), it->end());
+            hash = Hash(hash, *it);
         }
         nIndex >>= 1;
     }
@@ -60,7 +60,7 @@ static void MerkleComputation(const std::vector<uint256>& leaves, uint256* proot
                 }
             }
             mutated |= (inner[level] == h);
-            CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
+            CHash256().Write(inner[level]).Write(h).Finalize(h);
         }
         // Store the resulting hash at inner position level.
         inner[level] = h;
@@ -86,7 +86,7 @@ static void MerkleComputation(const std::vector<uint256>& leaves, uint256* proot
         if (pbranch && matchh) {
             pbranch->push_back(h);
         }
-        CHash256().Write(h.begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
+        CHash256().Write(h).Write(h).Finalize(h);
         // Increment count to the value it would have if two entries at this
         // level had existed.
         count += (((uint32_t)1) << level);
@@ -101,7 +101,7 @@ static void MerkleComputation(const std::vector<uint256>& leaves, uint256* proot
                     matchh = true;
                 }
             }
-            CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
+            CHash256().Write(inner[level]).Write(h).Finalize(h);
             level++;
         }
     }
@@ -144,8 +144,7 @@ static uint256 BlockBuildMerkleTree(const CBlock& block, bool* fMutated, std::ve
                 // Two identical hashes at the end of the list at a particular level.
                 mutated = true;
             }
-            vMerkleTree.push_back(Hash(vMerkleTree[j+i].begin(), vMerkleTree[j+i].end(),
-                                       vMerkleTree[j+i2].begin(), vMerkleTree[j+i2].end()));
+            vMerkleTree.push_back(Hash(vMerkleTree[j+i], vMerkleTree[j+i2]));
         }
         j += nSize;
     }
diff --git a/src/test/script_standard_tests.cpp b/src/test/script_standard_tests.cpp
index 77d748241b..87678af4d1 100644
--- a/src/test/script_standard_tests.cpp
+++ b/src/test/script_standard_tests.cpp
@@ -216,7 +216,7 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestination)
     s << OP_0 << ToByteVector(pubkey.GetID());
     BOOST_CHECK(ExtractDestination(s, address));
     WitnessV0KeyHash keyhash;
-    CHash160().Write(pubkey.begin(), pubkey.size()).Finalize(keyhash.begin());
+    CHash160().Write(pubkey).Finalize(keyhash);
     BOOST_CHECK(boost::get<WitnessV0KeyHash>(&address) && *boost::get<WitnessV0KeyHash>(&address) == keyhash);
 
     // TxoutType::WITNESS_V0_SCRIPTHASH
diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
index cb3ae290d1..0830743d61 100644
--- a/src/test/script_tests.cpp
+++ b/src/test/script_tests.cpp
@@ -282,7 +282,7 @@ public:
         CScript scriptPubKey = script;
         if (wm == WitnessMode::PKH) {
             uint160 hash;
-            CHash160().Write(&script[1], script.size() - 1).Finalize(hash.begin());
+            CHash160().Write(MakeSpan(script).subspan(1)).Finalize(hash);
             script = CScript() << OP_DUP << OP_HASH160 << ToByteVector(hash) << OP_EQUALVERIFY << OP_CHECKSIG;
             scriptPubKey = CScript() << witnessversion << ToByteVector(hash);
         } else if (wm == WitnessMode::SH) {
diff --git a/src/test/serialize_tests.cpp b/src/test/serialize_tests.cpp
index c2328f931c..f625b67c2a 100644
--- a/src/test/serialize_tests.cpp
+++ b/src/test/serialize_tests.cpp
@@ -145,7 +145,7 @@ BOOST_AUTO_TEST_CASE(floats)
     for (int i = 0; i < 1000; i++) {
         ss << float(i);
     }
-    BOOST_CHECK(Hash(ss.begin(), ss.end()) == uint256S("8e8b4cf3e4df8b332057e3e23af42ebc663b61e0495d5e7e32d85099d7f3fe0c"));
+    BOOST_CHECK(Hash(ss) == uint256S("8e8b4cf3e4df8b332057e3e23af42ebc663b61e0495d5e7e32d85099d7f3fe0c"));
 
     // decode
     for (int i = 0; i < 1000; i++) {
@@ -162,7 +162,7 @@ BOOST_AUTO_TEST_CASE(doubles)
     for (int i = 0; i < 1000; i++) {
         ss << double(i);
     }
-    BOOST_CHECK(Hash(ss.begin(), ss.end()) == uint256S("43d0c82591953c4eafe114590d392676a01585d25b25d433557f0d7878b23f96"));
+    BOOST_CHECK(Hash(ss) == uint256S("43d0c82591953c4eafe114590d392676a01585d25b25d433557f0d7878b23f96"));
 
     // decode
     for (int i = 0; i < 1000; i++) {
diff --git a/src/test/settings_tests.cpp b/src/test/settings_tests.cpp
index 1a2d775f49..91e039416c 100644
--- a/src/test/settings_tests.cpp
+++ b/src/test/settings_tests.cpp
@@ -228,7 +228,7 @@ BOOST_FIXTURE_TEST_CASE(Merge, MergeTestingSetup)
         if (OnlyHasDefaultSectionSetting(settings, network, name)) desc += " ignored";
         desc += "\n";
 
-        out_sha.Write((const unsigned char*)desc.data(), desc.size());
+        out_sha.Write(MakeUCharSpan(desc));
         if (out_file) {
             BOOST_REQUIRE(fwrite(desc.data(), 1, desc.size(), out_file) == desc.size());
         }
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index a30e366028..15a2c1e300 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -1009,7 +1009,7 @@ BOOST_FIXTURE_TEST_CASE(util_ArgsMerge, ArgsMergeTestingSetup)
 
         desc += "\n";
 
-        out_sha.Write((const unsigned char*)desc.data(), desc.size());
+        out_sha.Write(MakeUCharSpan(desc));
         if (out_file) {
             BOOST_REQUIRE(fwrite(desc.data(), 1, desc.size(), out_file) == desc.size());
         }
@@ -1112,7 +1112,7 @@ BOOST_FIXTURE_TEST_CASE(util_ChainMerge, ChainMergeTestingSetup)
         }
         desc += "\n";
 
-        out_sha.Write((const unsigned char*)desc.data(), desc.size());
+        out_sha.Write(MakeUCharSpan(desc));
         if (out_file) {
             BOOST_REQUIRE(fwrite(desc.data(), 1, desc.size(), out_file) == desc.size());
         }
@@ -2186,8 +2186,8 @@ BOOST_AUTO_TEST_CASE(message_hash)
         std::string(1, (char)unsigned_tx.length()) +
         unsigned_tx;
 
-    const uint256 signature_hash = Hash(unsigned_tx.begin(), unsigned_tx.end());
-    const uint256 message_hash1 = Hash(prefixed_message.begin(), prefixed_message.end());
+    const uint256 signature_hash = Hash(unsigned_tx);
+    const uint256 message_hash1 = Hash(prefixed_message);
     const uint256 message_hash2 = MessageHash(unsigned_tx);
 
     BOOST_CHECK_EQUAL(message_hash1, message_hash2);
diff --git a/src/uint256.cpp b/src/uint256.cpp
index a943e71062..a5dfba41e2 100644
--- a/src/uint256.cpp
+++ b/src/uint256.cpp
@@ -12,20 +12,20 @@
 template <unsigned int BITS>
 base_blob<BITS>::base_blob(const std::vector<unsigned char>& vch)
 {
-    assert(vch.size() == sizeof(data));
-    memcpy(data, vch.data(), sizeof(data));
+    assert(vch.size() == sizeof(m_data));
+    memcpy(m_data, vch.data(), sizeof(m_data));
 }
 
 template <unsigned int BITS>
 std::string base_blob<BITS>::GetHex() const
 {
-    return HexStr(std::reverse_iterator<const uint8_t*>(data + sizeof(data)), std::reverse_iterator<const uint8_t*>(data));
+    return HexStr(std::reverse_iterator<const uint8_t*>(m_data + sizeof(m_data)), std::reverse_iterator<const uint8_t*>(m_data));
 }
 
 template <unsigned int BITS>
 void base_blob<BITS>::SetHex(const char* psz)
 {
-    memset(data, 0, sizeof(data));
+    memset(m_data, 0, sizeof(m_data));
 
     // skip leading spaces
     while (IsSpace(*psz))
@@ -39,7 +39,7 @@ void base_blob<BITS>::SetHex(const char* psz)
     size_t digits = 0;
     while (::HexDigit(psz[digits]) != -1)
         digits++;
-    unsigned char* p1 = (unsigned char*)data;
+    unsigned char* p1 = (unsigned char*)m_data;
     unsigned char* pend = p1 + WIDTH;
     while (digits > 0 && p1 < pend) {
         *p1 = ::HexDigit(psz[--digits]);
diff --git a/src/uint256.h b/src/uint256.h
index b36598f572..8ab747ef49 100644
--- a/src/uint256.h
+++ b/src/uint256.h
@@ -18,11 +18,11 @@ class base_blob
 {
 protected:
     static constexpr int WIDTH = BITS / 8;
-    uint8_t data[WIDTH];
+    uint8_t m_data[WIDTH];
 public:
     base_blob()
     {
-        memset(data, 0, sizeof(data));
+        memset(m_data, 0, sizeof(m_data));
     }
 
     explicit base_blob(const std::vector<unsigned char>& vch);
@@ -30,17 +30,17 @@ public:
     bool IsNull() const
     {
         for (int i = 0; i < WIDTH; i++)
-            if (data[i] != 0)
+            if (m_data[i] != 0)
                 return false;
         return true;
     }
 
     void SetNull()
     {
-        memset(data, 0, sizeof(data));
+        memset(m_data, 0, sizeof(m_data));
     }
 
-    inline int Compare(const base_blob& other) const { return memcmp(data, other.data, sizeof(data)); }
+    inline int Compare(const base_blob& other) const { return memcmp(m_data, other.m_data, sizeof(m_data)); }
 
     friend inline bool operator==(const base_blob& a, const base_blob& b) { return a.Compare(b) == 0; }
     friend inline bool operator!=(const base_blob& a, const base_blob& b) { return a.Compare(b) != 0; }
@@ -51,34 +51,37 @@ public:
     void SetHex(const std::string& str);
     std::string ToString() const;
 
+    const unsigned char* data() const { return m_data; }
+    unsigned char* data() { return m_data; }
+
     unsigned char* begin()
     {
-        return &data[0];
+        return &m_data[0];
     }
 
     unsigned char* end()
     {
-        return &data[WIDTH];
+        return &m_data[WIDTH];
     }
 
     const unsigned char* begin() const
     {
-        return &data[0];
+        return &m_data[0];
     }
 
     const unsigned char* end() const
     {
-        return &data[WIDTH];
+        return &m_data[WIDTH];
     }
 
     unsigned int size() const
     {
-        return sizeof(data);
+        return sizeof(m_data);
     }
 
     uint64_t GetUint64(int pos) const
     {
-        const uint8_t* ptr = data + pos * 8;
+        const uint8_t* ptr = m_data + pos * 8;
         return ((uint64_t)ptr[0]) | \
                ((uint64_t)ptr[1]) << 8 | \
                ((uint64_t)ptr[2]) << 16 | \
@@ -92,13 +95,13 @@ public:
     template<typename Stream>
     void Serialize(Stream& s) const
     {
-        s.write((char*)data, sizeof(data));
+        s.write((char*)m_data, sizeof(m_data));
     }
 
     template<typename Stream>
     void Unserialize(Stream& s)
     {
-        s.read((char*)data, sizeof(data));
+        s.read((char*)m_data, sizeof(m_data));
     }
 };
 
diff --git a/src/validation.cpp b/src/validation.cpp
index 3cebf1090e..81af972777 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3434,7 +3434,7 @@ std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBloc
     if (consensusParams.SegwitHeight != std::numeric_limits<int>::max()) {
         if (commitpos == -1) {
             uint256 witnessroot = BlockWitnessMerkleRoot(block, nullptr);
-            CHash256().Write(witnessroot.begin(), 32).Write(ret.data(), 32).Finalize(witnessroot.begin());
+            CHash256().Write(witnessroot).Write(ret).Finalize(witnessroot);
             CTxOut out;
             out.nValue = 0;
             out.scriptPubKey.resize(MINIMUM_WITNESS_COMMITMENT);
@@ -3579,7 +3579,7 @@ static bool ContextualCheckBlock(const CBlock& block, BlockValidationState& stat
             if (block.vtx[0]->vin[0].scriptWitness.stack.size() != 1 || block.vtx[0]->vin[0].scriptWitness.stack[0].size() != 32) {
                 return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-witness-nonce-size", strprintf("%s : invalid witness reserved value size", __func__));
             }
-            CHash256().Write(hashWitness.begin(), 32).Write(&block.vtx[0]->vin[0].scriptWitness.stack[0][0], 32).Finalize(hashWitness.begin());
+            CHash256().Write(hashWitness).Write(block.vtx[0]->vin[0].scriptWitness.stack[0]).Finalize(hashWitness);
             if (memcmp(hashWitness.begin(), &block.vtx[0]->vout[commitpos].scriptPubKey[6], 32)) {
                 return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-witness-merkle-match", strprintf("%s : witness merkle commitment mismatch", __func__));
             }
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index d2770a46f7..7ef06663b5 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -630,13 +630,13 @@ static size_t CalculateNestedKeyhashInputSize(bool use_max_sig)
     CPubKey pubkey = key.GetPubKey();
 
     // Generate pubkey hash
-    uint160 key_hash(Hash160(pubkey.begin(), pubkey.end()));
+    uint160 key_hash(Hash160(pubkey));
 
     // Create inner-script to enter into keystore. Key hash can't be 0...
     CScript inner_script = CScript() << OP_0 << std::vector<unsigned char>(key_hash.begin(), key_hash.end());
 
     // Create outer P2SH script for the output
-    uint160 script_id(Hash160(inner_script.begin(), inner_script.end()));
+    uint160 script_id(Hash160(inner_script));
     CScript script_pubkey = CScript() << OP_HASH160 << std::vector<unsigned char>(script_id.begin(), script_id.end()) << OP_EQUAL;
 
     // Add inner-script to key store and key to watchonly
diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index a6d327994b..fa6814d0d3 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -103,7 +103,7 @@ bool WalletBatch::WriteKey(const CPubKey& vchPubKey, const CPrivKey& vchPrivKey,
     vchKey.insert(vchKey.end(), vchPubKey.begin(), vchPubKey.end());
     vchKey.insert(vchKey.end(), vchPrivKey.begin(), vchPrivKey.end());
 
-    return WriteIC(std::make_pair(DBKeys::KEY, vchPubKey), std::make_pair(vchPrivKey, Hash(vchKey.begin(), vchKey.end())), false);
+    return WriteIC(std::make_pair(DBKeys::KEY, vchPubKey), std::make_pair(vchPrivKey, Hash(vchKey)), false);
 }
 
 bool WalletBatch::WriteCryptedKey(const CPubKey& vchPubKey,
@@ -115,7 +115,7 @@ bool WalletBatch::WriteCryptedKey(const CPubKey& vchPubKey,
     }
 
     // Compute a checksum of the encrypted key
-    uint256 checksum = Hash(vchCryptedSecret.begin(), vchCryptedSecret.end());
+    uint256 checksum = Hash(vchCryptedSecret);
 
     const auto key = std::make_pair(DBKeys::CRYPTED_KEY, vchPubKey);
     if (!WriteIC(key, std::make_pair(vchCryptedSecret, checksum), false)) {
@@ -209,7 +209,7 @@ bool WalletBatch::WriteDescriptorKey(const uint256& desc_id, const CPubKey& pubk
     key.insert(key.end(), pubkey.begin(), pubkey.end());
     key.insert(key.end(), privkey.begin(), privkey.end());
 
-    return WriteIC(std::make_pair(DBKeys::WALLETDESCRIPTORKEY, std::make_pair(desc_id, pubkey)), std::make_pair(privkey, Hash(key.begin(), key.end())), false);
+    return WriteIC(std::make_pair(DBKeys::WALLETDESCRIPTORKEY, std::make_pair(desc_id, pubkey)), std::make_pair(privkey, Hash(key)), false);
 }
 
 bool WalletBatch::WriteCryptedDescriptorKey(const uint256& desc_id, const CPubKey& pubkey, const std::vector<unsigned char>& secret)
@@ -365,7 +365,7 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
                 vchKey.insert(vchKey.end(), vchPubKey.begin(), vchPubKey.end());
                 vchKey.insert(vchKey.end(), pkey.begin(), pkey.end());
 
-                if (Hash(vchKey.begin(), vchKey.end()) != hash)
+                if (Hash(vchKey) != hash)
                 {
                     strErr = "Error reading wallet database: CPubKey/CPrivKey corrupt";
                     return false;
@@ -414,7 +414,7 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
             if (!ssValue.eof()) {
                 uint256 checksum;
                 ssValue >> checksum;
-                if ((checksum_valid = Hash(vchPrivKey.begin(), vchPrivKey.end()) != checksum)) {
+                if ((checksum_valid = Hash(vchPrivKey) != checksum)) {
                     strErr = "Error reading wallet database: Crypted key corrupt";
                     return false;
                 }
@@ -621,7 +621,7 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
             to_hash.insert(to_hash.end(), pubkey.begin(), pubkey.end());
             to_hash.insert(to_hash.end(), pkey.begin(), pkey.end());
 
-            if (Hash(to_hash.begin(), to_hash.end()) != hash)
+            if (Hash(to_hash) != hash)
             {
                 strErr = "Error reading wallet database: CPubKey/CPrivKey corrupt";
                 return false;