diff --git a/configure.ac b/configure.ac
index 78d2cc7fe6..f5f3e030b8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -308,6 +308,8 @@ fi
 # be compiled with them, rather that specific objects/libs may use them after checking for runtime
 # compatibility.
 AX_CHECK_COMPILE_FLAG([-msse4.2],[[SSE42_CXXFLAGS="-msse4.2"]],,[[$CXXFLAG_WERROR]])
+AX_CHECK_COMPILE_FLAG([-msse4.1],[[SSE41_CXXFLAGS="-msse4.1"]],,[[$CXXFLAG_WERROR]])
+AX_CHECK_COMPILE_FLAG([-mavx -mavx2],[[AVX2_CXXFLAGS="-mavx -mavx2"]],,[[$CXXFLAG_WERROR]])
 
 TEMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS="$CXXFLAGS $SSE42_CXXFLAGS"
@@ -331,6 +333,44 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 )
 CXXFLAGS="$TEMP_CXXFLAGS"
 
+TEMP_CXXFLAGS="$CXXFLAGS"
+CXXFLAGS="$CXXFLAGS $SSE41_CXXFLAGS"
+AC_MSG_CHECKING(for SSE4.1 intrinsics)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+    #include <stdint.h>
+    #if defined(_MSC_VER)
+    #include <immintrin.h>
+    #elif defined(__GNUC__)
+    #include <x86intrin.h>
+    #endif
+  ]],[[
+    __m128i l = _mm_set1_epi32(0);
+    return _mm_extract_epi32(l, 3);
+  ]])],
+ [ AC_MSG_RESULT(yes); enable_sse41=yes; AC_DEFINE(ENABLE_SSE41, 1, [Define this symbol to build code that uses SSE4.1 intrinsics]) ],
+ [ AC_MSG_RESULT(no)]
+)
+CXXFLAGS="$TEMP_CXXFLAGS"
+
+TEMP_CXXFLAGS="$CXXFLAGS"
+CXXFLAGS="$CXXFLAGS $AVX2_CXXFLAGS"
+AC_MSG_CHECKING(for AVX2 intrinsics)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+    #include <stdint.h>
+    #if defined(_MSC_VER)
+    #include <immintrin.h>
+    #elif defined(__GNUC__) && defined(__AVX2__)
+    #include <x86intrin.h>
+    #endif
+  ]],[[
+    __m256i l = _mm256_set1_epi32(0);
+    return _mm256_extract_epi32(l, 7);
+  ]])],
+ [ AC_MSG_RESULT(yes); enable_avx2=yes; AC_DEFINE(ENABLE_AVX2, 1, [Define this symbol to build code that uses AVX2 intrinsics]) ],
+ [ AC_MSG_RESULT(no)]
+)
+CXXFLAGS="$TEMP_CXXFLAGS"
+
 CPPFLAGS="$CPPFLAGS -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS"
 
 AC_ARG_WITH([utils],
@@ -1242,6 +1282,8 @@ AM_CONDITIONAL([USE_LCOV],[test x$use_lcov = xyes])
 AM_CONDITIONAL([GLIBC_BACK_COMPAT],[test x$use_glibc_compat = xyes])
 AM_CONDITIONAL([HARDEN],[test x$use_hardening = xyes])
 AM_CONDITIONAL([ENABLE_HWCRC32],[test x$enable_hwcrc32 = xyes])
+AM_CONDITIONAL([ENABLE_SSE41],[test x$enable_sse41 = xyes])
+AM_CONDITIONAL([ENABLE_AVX2],[test x$enable_avx2 = xyes])
 AM_CONDITIONAL([USE_ASM],[test x$use_asm = xyes])
 
 AC_DEFINE(CLIENT_VERSION_MAJOR, _CLIENT_VERSION_MAJOR, [Major version])
@@ -1276,6 +1318,8 @@ AC_SUBST(HARDENED_LDFLAGS)
 AC_SUBST(PIC_FLAGS)
 AC_SUBST(PIE_FLAGS)
 AC_SUBST(SSE42_CXXFLAGS)
+AC_SUBST(SSE41_CXXFLAGS)
+AC_SUBST(AVX2_CXXFLAGS)
 AC_SUBST(LIBTOOL_APP_LDFLAGS)
 AC_SUBST(USE_UPNP)
 AC_SUBST(USE_QRCODE)
diff --git a/src/Makefile.am b/src/Makefile.am
index 72aa652329..7c267678d4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -51,6 +51,8 @@ LIBBITCOIN_CONSENSUS=libdash_consensus.a
 LIBBITCOIN_CLI=libdash_cli.a
 LIBBITCOIN_UTIL=libdash_util.a
 LIBBITCOIN_CRYPTO=crypto/libdash_crypto.a
+LIBBITCOIN_CRYPTO_SSE41=crypto/libbitcoin_crypto_sse41.a
+LIBBITCOIN_CRYPTO_AVX2=crypto/libbitcoin_crypto_avx2.a
 LIBBITCOINQT=qt/libdashqt.a
 LIBSECP256K1=secp256k1/libsecp256k1.la
 
@@ -71,6 +73,8 @@ $(LIBSECP256K1): $(wildcard secp256k1/src/*) $(wildcard secp256k1/include/*)
 # But to build the less dependent modules first, we manually select their order here:
 EXTRA_LIBRARIES += \
   $(LIBBITCOIN_CRYPTO) \
+  $(LIBBITCOIN_CRYPTO_SSE41) \
+  $(LIBBITCOIN_CRYPTO_AVX2) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_COMMON) \
   $(LIBBITCOIN_CONSENSUS) \
@@ -395,6 +399,22 @@ if USE_ASM
 crypto_libdash_crypto_a_SOURCES += crypto/sha256_sse4.cpp
 endif
 
+crypto_libbitcoin_crypto_sse41_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+crypto_libbitcoin_crypto_sse41_a_CPPFLAGS = $(AM_CPPFLAGS)
+if ENABLE_SSE41
+crypto_libbitcoin_crypto_sse41_a_CXXFLAGS += $(SSE41_CXXFLAGS)
+crypto_libbitcoin_crypto_sse41_a_CPPFLAGS += -DENABLE_SSE41
+endif
+crypto_libbitcoin_crypto_sse41_a_SOURCES = crypto/sha256_sse41.cpp
+
+crypto_libbitcoin_crypto_avx2_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+crypto_libbitcoin_crypto_avx2_a_CPPFLAGS = $(AM_CPPFLAGS)
+if ENABLE_AVX2
+crypto_libbitcoin_crypto_avx2_a_CXXFLAGS += $(AVX2_CXXFLAGS)
+crypto_libbitcoin_crypto_avx2_a_CPPFLAGS += -DENABLE_AVX2
+endif
+crypto_libbitcoin_crypto_avx2_a_SOURCES = crypto/sha256_avx2.cpp
+
 # x11
 crypto_libdash_crypto_a_SOURCES += \
   crypto/blake.c \
@@ -548,6 +568,8 @@ dashd_LDADD = \
   $(LIBBITCOIN_ZMQ) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
+  $(LIBBITCOIN_CRYPTO_SSE41) \
+  $(LIBBITCOIN_CRYPTO_AVX2) \
   $(LIBLEVELDB) \
   $(LIBLEVELDB_SSE42) \
   $(LIBMEMENV) \
@@ -569,7 +591,9 @@ dash_cli_LDADD = \
   $(LIBBITCOIN_CLI) \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_UTIL) \
-  $(LIBBITCOIN_CRYPTO)
+  $(LIBBITCOIN_CRYPTO) \
+  $(LIBBITCOIN_CRYPTO_SSE41) \
+  $(LIBBITCOIN_CRYPTO_AVX2)
 dash_cli_LDADD += $(BACKTRACE_LIB) $(BOOST_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(EVENT_LIBS) $(BLS_LIBS)
 #
 
@@ -589,6 +613,8 @@ dash_tx_LDADD = \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
+  $(LIBBITCOIN_CRYPTO_SSE41) \
+  $(LIBBITCOIN_CRYPTO_AVX2) \
   $(LIBSECP256K1)
 
 dash_tx_LDADD += $(BACKTRACE_LIB) $(BOOST_LIBS) $(CRYPTO_LIBS) $(BLS_LIBS)
diff --git a/src/Makefile.bench.include b/src/Makefile.bench.include
index 576d820c83..58ba5da136 100644
--- a/src/Makefile.bench.include
+++ b/src/Makefile.bench.include
@@ -26,6 +26,7 @@ bench_bench_dash_SOURCES = \
   bench/chacha_poly_aead.cpp \
   bench/crypto_hash.cpp \
   bench/ccoins_caching.cpp \
+  bench/merkle_root.cpp \
   bench/mempool_eviction.cpp \
   bench/base58.cpp \
   bench/lockedpool.cpp \
@@ -45,6 +46,8 @@ bench_bench_dash_LDADD = \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
+  $(LIBBITCOIN_CRYPTO_SSE41) \
+  $(LIBBITCOIN_CRYPTO_AVX2) \
   $(LIBLEVELDB) \
   $(LIBLEVELDB_SSE42) \
   $(LIBMEMENV) \
diff --git a/src/Makefile.qt.include b/src/Makefile.qt.include
index 26eb4dfc85..8acfc5adcd 100644
--- a/src/Makefile.qt.include
+++ b/src/Makefile.qt.include
@@ -647,7 +647,7 @@ endif
 if ENABLE_ZMQ
 qt_dash_qt_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
 endif
-qt_dash_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) \
+qt_dash_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBBITCOIN_CRYPTO_SSE41) $(LIBBITCOIN_CRYPTO_AVX2) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) \
   $(BACKTRACE_LIB) $(BOOST_LIBS) $(QT_LIBS) $(QT_DBUS_LIBS) $(QR_LIBS) $(PROTOBUF_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \
   $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(BLS_LIBS)
 qt_dash_qt_LDFLAGS = $(LDFLAGS_WRAP_EXCEPTIONS) $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
diff --git a/src/Makefile.qttest.include b/src/Makefile.qttest.include
index 5f2f3d02ec..c9a8f9e0d7 100644
--- a/src/Makefile.qttest.include
+++ b/src/Makefile.qttest.include
@@ -60,7 +60,7 @@ endif
 if ENABLE_ZMQ
 qt_test_test_dash_qt_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
 endif
-qt_test_test_dash_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) \
+qt_test_test_dash_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBBITCOIN_CRYPTO_SSE41) $(LIBBITCOIN_CRYPTO_AVX2) $(LIBUNIVALUE) $(LIBLEVELDB) \
   $(LIBLEVELDB_SSE42) $(LIBMEMENV) $(BACKTRACE_LIB) $(BOOST_LIBS) $(QT_DBUS_LIBS) $(QT_TEST_LIBS) $(QT_LIBS) \
   $(QR_LIBS) $(PROTOBUF_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \
   $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(BLS_LIBS)
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 6814545b78..3c519d0843 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -114,7 +114,7 @@ test_test_dash_LDADD =
 if ENABLE_WALLET
 test_test_dash_LDADD += $(LIBBITCOIN_WALLET)
 endif
-test_test_dash_LDADD += $(LIBBITCOIN_SERVER) $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) \
+test_test_dash_LDADD += $(LIBBITCOIN_SERVER) $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBBITCOIN_CRYPTO_SSE41) $(LIBBITCOIN_CRYPTO_AVX2) $(LIBUNIVALUE) \
   $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) $(BACKTRACE_LIB) $(BOOST_LIBS) $(BOOST_UNIT_TEST_FRAMEWORK_LIB) $(LIBSECP256K1) $(EVENT_LIBS) $(EVENT_PTHREADS_LIBS)
 test_test_dash_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 
@@ -139,6 +139,8 @@ test_test_dash_fuzzy_LDADD = \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
+  $(LIBBITCOIN_CRYPTO_SSE41) \
+  $(LIBBITCOIN_CRYPTO_AVX2) \
   $(LIBSECP256K1)
 
 test_test_dash_fuzzy_LDADD += $(BOOST_LIBS) $(CRYPTO_LIBS) $(BACKTRACE_LIB)
diff --git a/src/bench/crypto_hash.cpp b/src/bench/crypto_hash.cpp
index 1b0d1fa75e..592aab47a1 100644
--- a/src/bench/crypto_hash.cpp
+++ b/src/bench/crypto_hash.cpp
@@ -71,6 +71,14 @@ static void HASH_DSHA256_0032b(benchmark::State& state)
     }
 }
 
+static void SHA256D64_1024(benchmark::State& state)
+{
+    std::vector<uint8_t> in(64 * 1024, 0);
+    while (state.KeepRunning()) {
+        SHA256D64(in.data(), in.data(), 1024);
+    }
+}
+
 static void HASH_SHA512(benchmark::State& state)
 {
     uint8_t hash[CSHA512::OUTPUT_SIZE];
@@ -219,6 +227,7 @@ BENCHMARK(HASH_X11);
 BENCHMARK(HASH_SHA256_0032b);
 BENCHMARK(HASH_DSHA256_0032b);
 BENCHMARK(HASH_SipHash_0032b);
+BENCHMARK(SHA256D64_1024/*, 7400*/);
 
 BENCHMARK(HASH_DSHA256_0032b_single);
 BENCHMARK(HASH_DSHA256_0080b_single);
diff --git a/src/bench/merkle_root.cpp b/src/bench/merkle_root.cpp
new file mode 100644
index 0000000000..ae2a0a28dc
--- /dev/null
+++ b/src/bench/merkle_root.cpp
@@ -0,0 +1,26 @@
+// Copyright (c) 2016 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "bench.h"
+
+#include "uint256.h"
+#include "random.h"
+#include "consensus/merkle.h"
+
+static void MerkleRoot(benchmark::State& state)
+{
+    FastRandomContext rng(true);
+    std::vector<uint256> leaves;
+    leaves.resize(9001);
+    for (auto& item : leaves) {
+        item = rng.rand256();
+    }
+    while (state.KeepRunning()) {
+        bool mutation = false;
+        uint256 hash = ComputeMerkleRoot(std::vector<uint256>(leaves), &mutation);
+        leaves[mutation] = hash;
+    }
+}
+
+BENCHMARK(MerkleRoot, 800);
diff --git a/src/consensus/merkle.cpp b/src/consensus/merkle.cpp
index 8e8b04e6d6..6f4136f76b 100644
--- a/src/consensus/merkle.cpp
+++ b/src/consensus/merkle.cpp
@@ -42,118 +42,26 @@
        root.
 */
 
-/* This implements a constant-space merkle root/path calculator, limited to 2^32 leaves. */
-static void MerkleComputation(const std::vector<uint256>& leaves, uint256* proot, bool* pmutated, uint32_t branchpos, std::vector<uint256>* pbranch) {
-    if (pbranch) pbranch->clear();
-    if (leaves.size() == 0) {
-        if (pmutated) *pmutated = false;
-        if (proot) *proot = uint256();
-        return;
-    }
-    bool mutated = false;
-    // count is the number of leaves processed so far.
-    uint32_t count = 0;
-    // inner is an array of eagerly computed subtree hashes, indexed by tree
-    // level (0 being the leaves).
-    // For example, when count is 25 (11001 in binary), inner[4] is the hash of
-    // the first 16 leaves, inner[3] of the next 8 leaves, and inner[0] equal to
-    // the last leaf. The other inner entries are undefined.
-    uint256 inner[32];
-    // Which position in inner is a hash that depends on the matching leaf.
-    int matchlevel = -1;
-    // First process all leaves into 'inner' values.
-    while (count < leaves.size()) {
-        uint256 h = leaves[count];
-        bool matchh = count == branchpos;
-        count++;
-        int level;
-        // For each of the lower bits in count that are 0, do 1 step. Each
-        // corresponds to an inner value that existed before processing the
-        // current leaf, and each needs a hash to combine it.
-        for (level = 0; !(count & (((uint32_t)1) << level)); level++) {
-            if (pbranch) {
-                if (matchh) {
-                    pbranch->push_back(inner[level]);
-                } else if (matchlevel == level) {
-                    pbranch->push_back(h);
-                    matchh = true;
-                }
+
+uint256 ComputeMerkleRoot(std::vector<uint256> hashes, bool* mutated) {
+    bool mutation = false;
+    while (hashes.size() > 1) {
+        if (mutated) {
+            for (size_t pos = 0; pos + 1 < hashes.size(); pos += 2) {
+                if (hashes[pos] == hashes[pos + 1]) mutation = true;
             }
-            mutated |= (inner[level] == h);
-            CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
         }
-        // Store the resulting hash at inner position level.
-        inner[level] = h;
-        if (matchh) {
-            matchlevel = level;
+        if (hashes.size() & 1) {
+            hashes.push_back(hashes.back());
         }
+        SHA256D64(hashes[0].begin(), hashes[0].begin(), hashes.size() / 2);
+        hashes.resize(hashes.size() / 2);
     }
-    // Do a final 'sweep' over the rightmost branch of the tree to process
-    // odd levels, and reduce everything to a single top value.
-    // Level is the level (counted from the bottom) up to which we've sweeped.
-    int level = 0;
-    // As long as bit number level in count is zero, skip it. It means there
-    // is nothing left at this level.
-    while (!(count & (((uint32_t)1) << level))) {
-        level++;
-    }
-    uint256 h = inner[level];
-    bool matchh = matchlevel == level;
-    while (count != (((uint32_t)1) << level)) {
-        // If we reach this point, h is an inner value that is not the top.
-        // We combine it with itself (Bitcoin's special rule for odd levels in
-        // the tree) to produce a higher level one.
-        if (pbranch && matchh) {
-            pbranch->push_back(h);
-        }
-        CHash256().Write(h.begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
-        // Increment count to the value it would have if two entries at this
-        // level had existed.
-        count += (((uint32_t)1) << level);
-        level++;
-        // And propagate the result upwards accordingly.
-        while (!(count & (((uint32_t)1) << level))) {
-            if (pbranch) {
-                if (matchh) {
-                    pbranch->push_back(inner[level]);
-                } else if (matchlevel == level) {
-                    pbranch->push_back(h);
-                    matchh = true;
-                }
-            }
-            CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
-            level++;
-        }
-    }
-    // Return result.
-    if (pmutated) *pmutated = mutated;
-    if (proot) *proot = h;
+    if (mutated) *mutated = mutation;
+    if (hashes.size() == 0) return uint256();
+    return hashes[0];
 }
 
-uint256 ComputeMerkleRoot(const std::vector<uint256>& leaves, bool* mutated) {
-    uint256 hash;
-    MerkleComputation(leaves, &hash, mutated, -1, nullptr);
-    return hash;
-}
-
-std::vector<uint256> ComputeMerkleBranch(const std::vector<uint256>& leaves, uint32_t position) {
-    std::vector<uint256> ret;
-    MerkleComputation(leaves, nullptr, nullptr, position, &ret);
-    return ret;
-}
-
-uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint256>& vMerkleBranch, uint32_t nIndex) {
-    uint256 hash = leaf;
-    for (std::vector<uint256>::const_iterator it = vMerkleBranch.begin(); it != vMerkleBranch.end(); ++it) {
-        if (nIndex & 1) {
-            hash = Hash(BEGIN(*it), END(*it), BEGIN(hash), END(hash));
-        } else {
-            hash = Hash(BEGIN(hash), END(hash), BEGIN(*it), END(*it));
-        }
-        nIndex >>= 1;
-    }
-    return hash;
-}
 
 uint256 BlockMerkleRoot(const CBlock& block, bool* mutated)
 {
@@ -162,15 +70,6 @@ uint256 BlockMerkleRoot(const CBlock& block, bool* mutated)
     for (size_t s = 0; s < block.vtx.size(); s++) {
         leaves[s] = block.vtx[s]->GetHash();
     }
-    return ComputeMerkleRoot(leaves, mutated);
+    return ComputeMerkleRoot(std::move(leaves), mutated);
 }
 
-std::vector<uint256> BlockMerkleBranch(const CBlock& block, uint32_t position)
-{
-    std::vector<uint256> leaves;
-    leaves.resize(block.vtx.size());
-    for (size_t s = 0; s < block.vtx.size(); s++) {
-        leaves[s] = block.vtx[s]->GetHash();
-    }
-    return ComputeMerkleBranch(leaves, position);
-}
diff --git a/src/consensus/merkle.h b/src/consensus/merkle.h
index cbede22c6a..5e739a02ff 100644
--- a/src/consensus/merkle.h
+++ b/src/consensus/merkle.h
@@ -12,9 +12,7 @@
 #include "primitives/block.h"
 #include "uint256.h"
 
-uint256 ComputeMerkleRoot(const std::vector<uint256>& leaves, bool* mutated = nullptr);
-std::vector<uint256> ComputeMerkleBranch(const std::vector<uint256>& leaves, uint32_t position);
-uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint256>& branch, uint32_t position);
+uint256 ComputeMerkleRoot(std::vector<uint256> hashes, bool* mutated = nullptr);
 
 /*
  * Compute the Merkle root of the transactions in a block.
@@ -22,11 +20,4 @@ uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint2
  */
 uint256 BlockMerkleRoot(const CBlock& block, bool* mutated = nullptr);
 
-/*
- * Compute the Merkle branch for the tree of transactions in a block, for a
- * given position.
- * This can be verified using ComputeMerkleRootFromBranch.
- */
-std::vector<uint256> BlockMerkleBranch(const CBlock& block, uint32_t position);
-
 #endif
diff --git a/src/crypto/sha256.cpp b/src/crypto/sha256.cpp
index 29afe86ec7..5af5916e65 100644
--- a/src/crypto/sha256.cpp
+++ b/src/crypto/sha256.cpp
@@ -19,6 +19,16 @@ void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks);
 #endif
 #endif
 
+namespace sha256d64_sse41
+{
+void Transform_4way(unsigned char* out, const unsigned char* in);
+}
+
+namespace sha256d64_avx2
+{
+void Transform_8way(unsigned char* out, const unsigned char* in);
+}
+
 // Internal implementation code.
 namespace
 {
@@ -33,9 +43,9 @@ uint32_t inline sigma0(uint32_t x) { return (x >> 7 | x << 25) ^ (x >> 18 | x <<
 uint32_t inline sigma1(uint32_t x) { return (x >> 17 | x << 15) ^ (x >> 19 | x << 13) ^ (x >> 10); }
 
 /** One round of SHA-256. */
-void inline Round(uint32_t a, uint32_t b, uint32_t c, uint32_t& d, uint32_t e, uint32_t f, uint32_t g, uint32_t& h, uint32_t k, uint32_t w)
+void inline Round(uint32_t a, uint32_t b, uint32_t c, uint32_t& d, uint32_t e, uint32_t f, uint32_t g, uint32_t& h, uint32_t k)
 {
-    uint32_t t1 = h + Sigma1(e) + Ch(e, f, g) + k + w;
+    uint32_t t1 = h + Sigma1(e) + Ch(e, f, g) + k;
     uint32_t t2 = Sigma0(a) + Maj(a, b, c);
     d += t1;
     h = t1 + t2;
@@ -61,73 +71,73 @@ void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks)
         uint32_t a = s[0], b = s[1], c = s[2], d = s[3], e = s[4], f = s[5], g = s[6], h = s[7];
         uint32_t w0, w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13, w14, w15;
 
-        Round(a, b, c, d, e, f, g, h, 0x428a2f98, w0 = ReadBE32(chunk + 0));
-        Round(h, a, b, c, d, e, f, g, 0x71374491, w1 = ReadBE32(chunk + 4));
-        Round(g, h, a, b, c, d, e, f, 0xb5c0fbcf, w2 = ReadBE32(chunk + 8));
-        Round(f, g, h, a, b, c, d, e, 0xe9b5dba5, w3 = ReadBE32(chunk + 12));
-        Round(e, f, g, h, a, b, c, d, 0x3956c25b, w4 = ReadBE32(chunk + 16));
-        Round(d, e, f, g, h, a, b, c, 0x59f111f1, w5 = ReadBE32(chunk + 20));
-        Round(c, d, e, f, g, h, a, b, 0x923f82a4, w6 = ReadBE32(chunk + 24));
-        Round(b, c, d, e, f, g, h, a, 0xab1c5ed5, w7 = ReadBE32(chunk + 28));
-        Round(a, b, c, d, e, f, g, h, 0xd807aa98, w8 = ReadBE32(chunk + 32));
-        Round(h, a, b, c, d, e, f, g, 0x12835b01, w9 = ReadBE32(chunk + 36));
-        Round(g, h, a, b, c, d, e, f, 0x243185be, w10 = ReadBE32(chunk + 40));
-        Round(f, g, h, a, b, c, d, e, 0x550c7dc3, w11 = ReadBE32(chunk + 44));
-        Round(e, f, g, h, a, b, c, d, 0x72be5d74, w12 = ReadBE32(chunk + 48));
-        Round(d, e, f, g, h, a, b, c, 0x80deb1fe, w13 = ReadBE32(chunk + 52));
-        Round(c, d, e, f, g, h, a, b, 0x9bdc06a7, w14 = ReadBE32(chunk + 56));
-        Round(b, c, d, e, f, g, h, a, 0xc19bf174, w15 = ReadBE32(chunk + 60));
+        Round(a, b, c, d, e, f, g, h, 0x428a2f98 + (w0 = ReadBE32(chunk + 0)));
+        Round(h, a, b, c, d, e, f, g, 0x71374491 + (w1 = ReadBE32(chunk + 4)));
+        Round(g, h, a, b, c, d, e, f, 0xb5c0fbcf + (w2 = ReadBE32(chunk + 8)));
+        Round(f, g, h, a, b, c, d, e, 0xe9b5dba5 + (w3 = ReadBE32(chunk + 12)));
+        Round(e, f, g, h, a, b, c, d, 0x3956c25b + (w4 = ReadBE32(chunk + 16)));
+        Round(d, e, f, g, h, a, b, c, 0x59f111f1 + (w5 = ReadBE32(chunk + 20)));
+        Round(c, d, e, f, g, h, a, b, 0x923f82a4 + (w6 = ReadBE32(chunk + 24)));
+        Round(b, c, d, e, f, g, h, a, 0xab1c5ed5 + (w7 = ReadBE32(chunk + 28)));
+        Round(a, b, c, d, e, f, g, h, 0xd807aa98 + (w8 = ReadBE32(chunk + 32)));
+        Round(h, a, b, c, d, e, f, g, 0x12835b01 + (w9 = ReadBE32(chunk + 36)));
+        Round(g, h, a, b, c, d, e, f, 0x243185be + (w10 = ReadBE32(chunk + 40)));
+        Round(f, g, h, a, b, c, d, e, 0x550c7dc3 + (w11 = ReadBE32(chunk + 44)));
+        Round(e, f, g, h, a, b, c, d, 0x72be5d74 + (w12 = ReadBE32(chunk + 48)));
+        Round(d, e, f, g, h, a, b, c, 0x80deb1fe + (w13 = ReadBE32(chunk + 52)));
+        Round(c, d, e, f, g, h, a, b, 0x9bdc06a7 + (w14 = ReadBE32(chunk + 56)));
+        Round(b, c, d, e, f, g, h, a, 0xc19bf174 + (w15 = ReadBE32(chunk + 60)));
 
-        Round(a, b, c, d, e, f, g, h, 0xe49b69c1, w0 += sigma1(w14) + w9 + sigma0(w1));
-        Round(h, a, b, c, d, e, f, g, 0xefbe4786, w1 += sigma1(w15) + w10 + sigma0(w2));
-        Round(g, h, a, b, c, d, e, f, 0x0fc19dc6, w2 += sigma1(w0) + w11 + sigma0(w3));
-        Round(f, g, h, a, b, c, d, e, 0x240ca1cc, w3 += sigma1(w1) + w12 + sigma0(w4));
-        Round(e, f, g, h, a, b, c, d, 0x2de92c6f, w4 += sigma1(w2) + w13 + sigma0(w5));
-        Round(d, e, f, g, h, a, b, c, 0x4a7484aa, w5 += sigma1(w3) + w14 + sigma0(w6));
-        Round(c, d, e, f, g, h, a, b, 0x5cb0a9dc, w6 += sigma1(w4) + w15 + sigma0(w7));
-        Round(b, c, d, e, f, g, h, a, 0x76f988da, w7 += sigma1(w5) + w0 + sigma0(w8));
-        Round(a, b, c, d, e, f, g, h, 0x983e5152, w8 += sigma1(w6) + w1 + sigma0(w9));
-        Round(h, a, b, c, d, e, f, g, 0xa831c66d, w9 += sigma1(w7) + w2 + sigma0(w10));
-        Round(g, h, a, b, c, d, e, f, 0xb00327c8, w10 += sigma1(w8) + w3 + sigma0(w11));
-        Round(f, g, h, a, b, c, d, e, 0xbf597fc7, w11 += sigma1(w9) + w4 + sigma0(w12));
-        Round(e, f, g, h, a, b, c, d, 0xc6e00bf3, w12 += sigma1(w10) + w5 + sigma0(w13));
-        Round(d, e, f, g, h, a, b, c, 0xd5a79147, w13 += sigma1(w11) + w6 + sigma0(w14));
-        Round(c, d, e, f, g, h, a, b, 0x06ca6351, w14 += sigma1(w12) + w7 + sigma0(w15));
-        Round(b, c, d, e, f, g, h, a, 0x14292967, w15 += sigma1(w13) + w8 + sigma0(w0));
+        Round(a, b, c, d, e, f, g, h, 0xe49b69c1 + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+        Round(h, a, b, c, d, e, f, g, 0xefbe4786 + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+        Round(g, h, a, b, c, d, e, f, 0x0fc19dc6 + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+        Round(f, g, h, a, b, c, d, e, 0x240ca1cc + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+        Round(e, f, g, h, a, b, c, d, 0x2de92c6f + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+        Round(d, e, f, g, h, a, b, c, 0x4a7484aa + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+        Round(c, d, e, f, g, h, a, b, 0x5cb0a9dc + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+        Round(b, c, d, e, f, g, h, a, 0x76f988da + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+        Round(a, b, c, d, e, f, g, h, 0x983e5152 + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+        Round(h, a, b, c, d, e, f, g, 0xa831c66d + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+        Round(g, h, a, b, c, d, e, f, 0xb00327c8 + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+        Round(f, g, h, a, b, c, d, e, 0xbf597fc7 + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+        Round(e, f, g, h, a, b, c, d, 0xc6e00bf3 + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+        Round(d, e, f, g, h, a, b, c, 0xd5a79147 + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+        Round(c, d, e, f, g, h, a, b, 0x06ca6351 + (w14 += sigma1(w12) + w7 + sigma0(w15)));
+        Round(b, c, d, e, f, g, h, a, 0x14292967 + (w15 += sigma1(w13) + w8 + sigma0(w0)));
 
-        Round(a, b, c, d, e, f, g, h, 0x27b70a85, w0 += sigma1(w14) + w9 + sigma0(w1));
-        Round(h, a, b, c, d, e, f, g, 0x2e1b2138, w1 += sigma1(w15) + w10 + sigma0(w2));
-        Round(g, h, a, b, c, d, e, f, 0x4d2c6dfc, w2 += sigma1(w0) + w11 + sigma0(w3));
-        Round(f, g, h, a, b, c, d, e, 0x53380d13, w3 += sigma1(w1) + w12 + sigma0(w4));
-        Round(e, f, g, h, a, b, c, d, 0x650a7354, w4 += sigma1(w2) + w13 + sigma0(w5));
-        Round(d, e, f, g, h, a, b, c, 0x766a0abb, w5 += sigma1(w3) + w14 + sigma0(w6));
-        Round(c, d, e, f, g, h, a, b, 0x81c2c92e, w6 += sigma1(w4) + w15 + sigma0(w7));
-        Round(b, c, d, e, f, g, h, a, 0x92722c85, w7 += sigma1(w5) + w0 + sigma0(w8));
-        Round(a, b, c, d, e, f, g, h, 0xa2bfe8a1, w8 += sigma1(w6) + w1 + sigma0(w9));
-        Round(h, a, b, c, d, e, f, g, 0xa81a664b, w9 += sigma1(w7) + w2 + sigma0(w10));
-        Round(g, h, a, b, c, d, e, f, 0xc24b8b70, w10 += sigma1(w8) + w3 + sigma0(w11));
-        Round(f, g, h, a, b, c, d, e, 0xc76c51a3, w11 += sigma1(w9) + w4 + sigma0(w12));
-        Round(e, f, g, h, a, b, c, d, 0xd192e819, w12 += sigma1(w10) + w5 + sigma0(w13));
-        Round(d, e, f, g, h, a, b, c, 0xd6990624, w13 += sigma1(w11) + w6 + sigma0(w14));
-        Round(c, d, e, f, g, h, a, b, 0xf40e3585, w14 += sigma1(w12) + w7 + sigma0(w15));
-        Round(b, c, d, e, f, g, h, a, 0x106aa070, w15 += sigma1(w13) + w8 + sigma0(w0));
+        Round(a, b, c, d, e, f, g, h, 0x27b70a85 + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+        Round(h, a, b, c, d, e, f, g, 0x2e1b2138 + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+        Round(g, h, a, b, c, d, e, f, 0x4d2c6dfc + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+        Round(f, g, h, a, b, c, d, e, 0x53380d13 + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+        Round(e, f, g, h, a, b, c, d, 0x650a7354 + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+        Round(d, e, f, g, h, a, b, c, 0x766a0abb + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+        Round(c, d, e, f, g, h, a, b, 0x81c2c92e + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+        Round(b, c, d, e, f, g, h, a, 0x92722c85 + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+        Round(a, b, c, d, e, f, g, h, 0xa2bfe8a1 + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+        Round(h, a, b, c, d, e, f, g, 0xa81a664b + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+        Round(g, h, a, b, c, d, e, f, 0xc24b8b70 + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+        Round(f, g, h, a, b, c, d, e, 0xc76c51a3 + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+        Round(e, f, g, h, a, b, c, d, 0xd192e819 + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+        Round(d, e, f, g, h, a, b, c, 0xd6990624 + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+        Round(c, d, e, f, g, h, a, b, 0xf40e3585 + (w14 += sigma1(w12) + w7 + sigma0(w15)));
+        Round(b, c, d, e, f, g, h, a, 0x106aa070 + (w15 += sigma1(w13) + w8 + sigma0(w0)));
 
-        Round(a, b, c, d, e, f, g, h, 0x19a4c116, w0 += sigma1(w14) + w9 + sigma0(w1));
-        Round(h, a, b, c, d, e, f, g, 0x1e376c08, w1 += sigma1(w15) + w10 + sigma0(w2));
-        Round(g, h, a, b, c, d, e, f, 0x2748774c, w2 += sigma1(w0) + w11 + sigma0(w3));
-        Round(f, g, h, a, b, c, d, e, 0x34b0bcb5, w3 += sigma1(w1) + w12 + sigma0(w4));
-        Round(e, f, g, h, a, b, c, d, 0x391c0cb3, w4 += sigma1(w2) + w13 + sigma0(w5));
-        Round(d, e, f, g, h, a, b, c, 0x4ed8aa4a, w5 += sigma1(w3) + w14 + sigma0(w6));
-        Round(c, d, e, f, g, h, a, b, 0x5b9cca4f, w6 += sigma1(w4) + w15 + sigma0(w7));
-        Round(b, c, d, e, f, g, h, a, 0x682e6ff3, w7 += sigma1(w5) + w0 + sigma0(w8));
-        Round(a, b, c, d, e, f, g, h, 0x748f82ee, w8 += sigma1(w6) + w1 + sigma0(w9));
-        Round(h, a, b, c, d, e, f, g, 0x78a5636f, w9 += sigma1(w7) + w2 + sigma0(w10));
-        Round(g, h, a, b, c, d, e, f, 0x84c87814, w10 += sigma1(w8) + w3 + sigma0(w11));
-        Round(f, g, h, a, b, c, d, e, 0x8cc70208, w11 += sigma1(w9) + w4 + sigma0(w12));
-        Round(e, f, g, h, a, b, c, d, 0x90befffa, w12 += sigma1(w10) + w5 + sigma0(w13));
-        Round(d, e, f, g, h, a, b, c, 0xa4506ceb, w13 += sigma1(w11) + w6 + sigma0(w14));
-        Round(c, d, e, f, g, h, a, b, 0xbef9a3f7, w14 + sigma1(w12) + w7 + sigma0(w15));
-        Round(b, c, d, e, f, g, h, a, 0xc67178f2, w15 + sigma1(w13) + w8 + sigma0(w0));
+        Round(a, b, c, d, e, f, g, h, 0x19a4c116 + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+        Round(h, a, b, c, d, e, f, g, 0x1e376c08 + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+        Round(g, h, a, b, c, d, e, f, 0x2748774c + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+        Round(f, g, h, a, b, c, d, e, 0x34b0bcb5 + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+        Round(e, f, g, h, a, b, c, d, 0x391c0cb3 + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+        Round(d, e, f, g, h, a, b, c, 0x4ed8aa4a + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+        Round(c, d, e, f, g, h, a, b, 0x5b9cca4f + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+        Round(b, c, d, e, f, g, h, a, 0x682e6ff3 + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+        Round(a, b, c, d, e, f, g, h, 0x748f82ee + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+        Round(h, a, b, c, d, e, f, g, 0x78a5636f + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+        Round(g, h, a, b, c, d, e, f, 0x84c87814 + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+        Round(f, g, h, a, b, c, d, e, 0x8cc70208 + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+        Round(e, f, g, h, a, b, c, d, 0x90befffa + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+        Round(d, e, f, g, h, a, b, c, 0xa4506ceb + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+        Round(c, d, e, f, g, h, a, b, 0xbef9a3f7 + (w14 + sigma1(w12) + w7 + sigma0(w15)));
+        Round(b, c, d, e, f, g, h, a, 0xc67178f2 + (w15 + sigma1(w13) + w8 + sigma0(w0)));
 
         s[0] += a;
         s[1] += b;
@@ -141,9 +151,300 @@ void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks)
     }
 }
 
+void TransformD64(unsigned char* out, const unsigned char* in)
+{
+    // Transform 1
+    uint32_t a = 0x6a09e667ul;
+    uint32_t b = 0xbb67ae85ul;
+    uint32_t c = 0x3c6ef372ul;
+    uint32_t d = 0xa54ff53aul;
+    uint32_t e = 0x510e527ful;
+    uint32_t f = 0x9b05688cul;
+    uint32_t g = 0x1f83d9abul;
+    uint32_t h = 0x5be0cd19ul;
+
+    uint32_t w0, w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13, w14, w15;
+
+    Round(a, b, c, d, e, f, g, h, 0x428a2f98ul + (w0 = ReadBE32(in + 0)));
+    Round(h, a, b, c, d, e, f, g, 0x71374491ul + (w1 = ReadBE32(in + 4)));
+    Round(g, h, a, b, c, d, e, f, 0xb5c0fbcful + (w2 = ReadBE32(in + 8)));
+    Round(f, g, h, a, b, c, d, e, 0xe9b5dba5ul + (w3 = ReadBE32(in + 12)));
+    Round(e, f, g, h, a, b, c, d, 0x3956c25bul + (w4 = ReadBE32(in + 16)));
+    Round(d, e, f, g, h, a, b, c, 0x59f111f1ul + (w5 = ReadBE32(in + 20)));
+    Round(c, d, e, f, g, h, a, b, 0x923f82a4ul + (w6 = ReadBE32(in + 24)));
+    Round(b, c, d, e, f, g, h, a, 0xab1c5ed5ul + (w7 = ReadBE32(in + 28)));
+    Round(a, b, c, d, e, f, g, h, 0xd807aa98ul + (w8 = ReadBE32(in + 32)));
+    Round(h, a, b, c, d, e, f, g, 0x12835b01ul + (w9 = ReadBE32(in + 36)));
+    Round(g, h, a, b, c, d, e, f, 0x243185beul + (w10 = ReadBE32(in + 40)));
+    Round(f, g, h, a, b, c, d, e, 0x550c7dc3ul + (w11 = ReadBE32(in + 44)));
+    Round(e, f, g, h, a, b, c, d, 0x72be5d74ul + (w12 = ReadBE32(in + 48)));
+    Round(d, e, f, g, h, a, b, c, 0x80deb1feul + (w13 = ReadBE32(in + 52)));
+    Round(c, d, e, f, g, h, a, b, 0x9bdc06a7ul + (w14 = ReadBE32(in + 56)));
+    Round(b, c, d, e, f, g, h, a, 0xc19bf174ul + (w15 = ReadBE32(in + 60)));
+    Round(a, b, c, d, e, f, g, h, 0xe49b69c1ul + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+    Round(h, a, b, c, d, e, f, g, 0xefbe4786ul + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+    Round(g, h, a, b, c, d, e, f, 0x0fc19dc6ul + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+    Round(f, g, h, a, b, c, d, e, 0x240ca1ccul + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+    Round(e, f, g, h, a, b, c, d, 0x2de92c6ful + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+    Round(d, e, f, g, h, a, b, c, 0x4a7484aaul + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+    Round(c, d, e, f, g, h, a, b, 0x5cb0a9dcul + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+    Round(b, c, d, e, f, g, h, a, 0x76f988daul + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+    Round(a, b, c, d, e, f, g, h, 0x983e5152ul + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+    Round(h, a, b, c, d, e, f, g, 0xa831c66dul + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+    Round(g, h, a, b, c, d, e, f, 0xb00327c8ul + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+    Round(f, g, h, a, b, c, d, e, 0xbf597fc7ul + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+    Round(e, f, g, h, a, b, c, d, 0xc6e00bf3ul + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+    Round(d, e, f, g, h, a, b, c, 0xd5a79147ul + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+    Round(c, d, e, f, g, h, a, b, 0x06ca6351ul + (w14 += sigma1(w12) + w7 + sigma0(w15)));
+    Round(b, c, d, e, f, g, h, a, 0x14292967ul + (w15 += sigma1(w13) + w8 + sigma0(w0)));
+    Round(a, b, c, d, e, f, g, h, 0x27b70a85ul + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+    Round(h, a, b, c, d, e, f, g, 0x2e1b2138ul + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+    Round(g, h, a, b, c, d, e, f, 0x4d2c6dfcul + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+    Round(f, g, h, a, b, c, d, e, 0x53380d13ul + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+    Round(e, f, g, h, a, b, c, d, 0x650a7354ul + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+    Round(d, e, f, g, h, a, b, c, 0x766a0abbul + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+    Round(c, d, e, f, g, h, a, b, 0x81c2c92eul + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+    Round(b, c, d, e, f, g, h, a, 0x92722c85ul + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+    Round(a, b, c, d, e, f, g, h, 0xa2bfe8a1ul + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+    Round(h, a, b, c, d, e, f, g, 0xa81a664bul + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+    Round(g, h, a, b, c, d, e, f, 0xc24b8b70ul + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+    Round(f, g, h, a, b, c, d, e, 0xc76c51a3ul + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+    Round(e, f, g, h, a, b, c, d, 0xd192e819ul + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+    Round(d, e, f, g, h, a, b, c, 0xd6990624ul + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+    Round(c, d, e, f, g, h, a, b, 0xf40e3585ul + (w14 += sigma1(w12) + w7 + sigma0(w15)));
+    Round(b, c, d, e, f, g, h, a, 0x106aa070ul + (w15 += sigma1(w13) + w8 + sigma0(w0)));
+    Round(a, b, c, d, e, f, g, h, 0x19a4c116ul + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+    Round(h, a, b, c, d, e, f, g, 0x1e376c08ul + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+    Round(g, h, a, b, c, d, e, f, 0x2748774cul + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+    Round(f, g, h, a, b, c, d, e, 0x34b0bcb5ul + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+    Round(e, f, g, h, a, b, c, d, 0x391c0cb3ul + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+    Round(d, e, f, g, h, a, b, c, 0x4ed8aa4aul + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+    Round(c, d, e, f, g, h, a, b, 0x5b9cca4ful + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+    Round(b, c, d, e, f, g, h, a, 0x682e6ff3ul + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+    Round(a, b, c, d, e, f, g, h, 0x748f82eeul + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+    Round(h, a, b, c, d, e, f, g, 0x78a5636ful + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+    Round(g, h, a, b, c, d, e, f, 0x84c87814ul + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+    Round(f, g, h, a, b, c, d, e, 0x8cc70208ul + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+    Round(e, f, g, h, a, b, c, d, 0x90befffaul + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+    Round(d, e, f, g, h, a, b, c, 0xa4506cebul + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+    Round(c, d, e, f, g, h, a, b, 0xbef9a3f7ul + (w14 + sigma1(w12) + w7 + sigma0(w15)));
+    Round(b, c, d, e, f, g, h, a, 0xc67178f2ul + (w15 + sigma1(w13) + w8 + sigma0(w0)));
+
+    a += 0x6a09e667ul;
+    b += 0xbb67ae85ul;
+    c += 0x3c6ef372ul;
+    d += 0xa54ff53aul;
+    e += 0x510e527ful;
+    f += 0x9b05688cul;
+    g += 0x1f83d9abul;
+    h += 0x5be0cd19ul;
+
+    uint32_t t0 = a, t1 = b, t2 = c, t3 = d, t4 = e, t5 = f, t6 = g, t7 = h;
+
+    // Transform 2
+    Round(a, b, c, d, e, f, g, h, 0xc28a2f98ul);
+    Round(h, a, b, c, d, e, f, g, 0x71374491ul);
+    Round(g, h, a, b, c, d, e, f, 0xb5c0fbcful);
+    Round(f, g, h, a, b, c, d, e, 0xe9b5dba5ul);
+    Round(e, f, g, h, a, b, c, d, 0x3956c25bul);
+    Round(d, e, f, g, h, a, b, c, 0x59f111f1ul);
+    Round(c, d, e, f, g, h, a, b, 0x923f82a4ul);
+    Round(b, c, d, e, f, g, h, a, 0xab1c5ed5ul);
+    Round(a, b, c, d, e, f, g, h, 0xd807aa98ul);
+    Round(h, a, b, c, d, e, f, g, 0x12835b01ul);
+    Round(g, h, a, b, c, d, e, f, 0x243185beul);
+    Round(f, g, h, a, b, c, d, e, 0x550c7dc3ul);
+    Round(e, f, g, h, a, b, c, d, 0x72be5d74ul);
+    Round(d, e, f, g, h, a, b, c, 0x80deb1feul);
+    Round(c, d, e, f, g, h, a, b, 0x9bdc06a7ul);
+    Round(b, c, d, e, f, g, h, a, 0xc19bf374ul);
+    Round(a, b, c, d, e, f, g, h, 0x649b69c1ul);
+    Round(h, a, b, c, d, e, f, g, 0xf0fe4786ul);
+    Round(g, h, a, b, c, d, e, f, 0x0fe1edc6ul);
+    Round(f, g, h, a, b, c, d, e, 0x240cf254ul);
+    Round(e, f, g, h, a, b, c, d, 0x4fe9346ful);
+    Round(d, e, f, g, h, a, b, c, 0x6cc984beul);
+    Round(c, d, e, f, g, h, a, b, 0x61b9411eul);
+    Round(b, c, d, e, f, g, h, a, 0x16f988faul);
+    Round(a, b, c, d, e, f, g, h, 0xf2c65152ul);
+    Round(h, a, b, c, d, e, f, g, 0xa88e5a6dul);
+    Round(g, h, a, b, c, d, e, f, 0xb019fc65ul);
+    Round(f, g, h, a, b, c, d, e, 0xb9d99ec7ul);
+    Round(e, f, g, h, a, b, c, d, 0x9a1231c3ul);
+    Round(d, e, f, g, h, a, b, c, 0xe70eeaa0ul);
+    Round(c, d, e, f, g, h, a, b, 0xfdb1232bul);
+    Round(b, c, d, e, f, g, h, a, 0xc7353eb0ul);
+    Round(a, b, c, d, e, f, g, h, 0x3069bad5ul);
+    Round(h, a, b, c, d, e, f, g, 0xcb976d5ful);
+    Round(g, h, a, b, c, d, e, f, 0x5a0f118ful);
+    Round(f, g, h, a, b, c, d, e, 0xdc1eeefdul);
+    Round(e, f, g, h, a, b, c, d, 0x0a35b689ul);
+    Round(d, e, f, g, h, a, b, c, 0xde0b7a04ul);
+    Round(c, d, e, f, g, h, a, b, 0x58f4ca9dul);
+    Round(b, c, d, e, f, g, h, a, 0xe15d5b16ul);
+    Round(a, b, c, d, e, f, g, h, 0x007f3e86ul);
+    Round(h, a, b, c, d, e, f, g, 0x37088980ul);
+    Round(g, h, a, b, c, d, e, f, 0xa507ea32ul);
+    Round(f, g, h, a, b, c, d, e, 0x6fab9537ul);
+    Round(e, f, g, h, a, b, c, d, 0x17406110ul);
+    Round(d, e, f, g, h, a, b, c, 0x0d8cd6f1ul);
+    Round(c, d, e, f, g, h, a, b, 0xcdaa3b6dul);
+    Round(b, c, d, e, f, g, h, a, 0xc0bbbe37ul);
+    Round(a, b, c, d, e, f, g, h, 0x83613bdaul);
+    Round(h, a, b, c, d, e, f, g, 0xdb48a363ul);
+    Round(g, h, a, b, c, d, e, f, 0x0b02e931ul);
+    Round(f, g, h, a, b, c, d, e, 0x6fd15ca7ul);
+    Round(e, f, g, h, a, b, c, d, 0x521afacaul);
+    Round(d, e, f, g, h, a, b, c, 0x31338431ul);
+    Round(c, d, e, f, g, h, a, b, 0x6ed41a95ul);
+    Round(b, c, d, e, f, g, h, a, 0x6d437890ul);
+    Round(a, b, c, d, e, f, g, h, 0xc39c91f2ul);
+    Round(h, a, b, c, d, e, f, g, 0x9eccabbdul);
+    Round(g, h, a, b, c, d, e, f, 0xb5c9a0e6ul);
+    Round(f, g, h, a, b, c, d, e, 0x532fb63cul);
+    Round(e, f, g, h, a, b, c, d, 0xd2c741c6ul);
+    Round(d, e, f, g, h, a, b, c, 0x07237ea3ul);
+    Round(c, d, e, f, g, h, a, b, 0xa4954b68ul);
+    Round(b, c, d, e, f, g, h, a, 0x4c191d76ul);
+
+    w0 = t0 + a;
+    w1 = t1 + b;
+    w2 = t2 + c;
+    w3 = t3 + d;
+    w4 = t4 + e;
+    w5 = t5 + f;
+    w6 = t6 + g;
+    w7 = t7 + h;
+
+    // Transform 3
+    a = 0x6a09e667ul;
+    b = 0xbb67ae85ul;
+    c = 0x3c6ef372ul;
+    d = 0xa54ff53aul;
+    e = 0x510e527ful;
+    f = 0x9b05688cul;
+    g = 0x1f83d9abul;
+    h = 0x5be0cd19ul;
+
+    Round(a, b, c, d, e, f, g, h, 0x428a2f98ul + w0);
+    Round(h, a, b, c, d, e, f, g, 0x71374491ul + w1);
+    Round(g, h, a, b, c, d, e, f, 0xb5c0fbcful + w2);
+    Round(f, g, h, a, b, c, d, e, 0xe9b5dba5ul + w3);
+    Round(e, f, g, h, a, b, c, d, 0x3956c25bul + w4);
+    Round(d, e, f, g, h, a, b, c, 0x59f111f1ul + w5);
+    Round(c, d, e, f, g, h, a, b, 0x923f82a4ul + w6);
+    Round(b, c, d, e, f, g, h, a, 0xab1c5ed5ul + w7);
+    Round(a, b, c, d, e, f, g, h, 0x5807aa98ul);
+    Round(h, a, b, c, d, e, f, g, 0x12835b01ul);
+    Round(g, h, a, b, c, d, e, f, 0x243185beul);
+    Round(f, g, h, a, b, c, d, e, 0x550c7dc3ul);
+    Round(e, f, g, h, a, b, c, d, 0x72be5d74ul);
+    Round(d, e, f, g, h, a, b, c, 0x80deb1feul);
+    Round(c, d, e, f, g, h, a, b, 0x9bdc06a7ul);
+    Round(b, c, d, e, f, g, h, a, 0xc19bf274ul);
+    Round(a, b, c, d, e, f, g, h, 0xe49b69c1ul + (w0 += sigma0(w1)));
+    Round(h, a, b, c, d, e, f, g, 0xefbe4786ul + (w1 += 0xa00000ul + sigma0(w2)));
+    Round(g, h, a, b, c, d, e, f, 0x0fc19dc6ul + (w2 += sigma1(w0) + sigma0(w3)));
+    Round(f, g, h, a, b, c, d, e, 0x240ca1ccul + (w3 += sigma1(w1) + sigma0(w4)));
+    Round(e, f, g, h, a, b, c, d, 0x2de92c6ful + (w4 += sigma1(w2) + sigma0(w5)));
+    Round(d, e, f, g, h, a, b, c, 0x4a7484aaul + (w5 += sigma1(w3) + sigma0(w6)));
+    Round(c, d, e, f, g, h, a, b, 0x5cb0a9dcul + (w6 += sigma1(w4) + 0x100ul + sigma0(w7)));
+    Round(b, c, d, e, f, g, h, a, 0x76f988daul + (w7 += sigma1(w5) + w0 + 0x11002000ul));
+    Round(a, b, c, d, e, f, g, h, 0x983e5152ul + (w8 = 0x80000000ul + sigma1(w6) + w1));
+    Round(h, a, b, c, d, e, f, g, 0xa831c66dul + (w9 = sigma1(w7) + w2));
+    Round(g, h, a, b, c, d, e, f, 0xb00327c8ul + (w10 = sigma1(w8) + w3));
+    Round(f, g, h, a, b, c, d, e, 0xbf597fc7ul + (w11 = sigma1(w9) + w4));
+    Round(e, f, g, h, a, b, c, d, 0xc6e00bf3ul + (w12 = sigma1(w10) + w5));
+    Round(d, e, f, g, h, a, b, c, 0xd5a79147ul + (w13 = sigma1(w11) + w6));
+    Round(c, d, e, f, g, h, a, b, 0x06ca6351ul + (w14 = sigma1(w12) + w7 + 0x400022ul));
+    Round(b, c, d, e, f, g, h, a, 0x14292967ul + (w15 = 0x100ul + sigma1(w13) + w8 + sigma0(w0)));
+    Round(a, b, c, d, e, f, g, h, 0x27b70a85ul + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+    Round(h, a, b, c, d, e, f, g, 0x2e1b2138ul + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+    Round(g, h, a, b, c, d, e, f, 0x4d2c6dfcul + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+    Round(f, g, h, a, b, c, d, e, 0x53380d13ul + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+    Round(e, f, g, h, a, b, c, d, 0x650a7354ul + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+    Round(d, e, f, g, h, a, b, c, 0x766a0abbul + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+    Round(c, d, e, f, g, h, a, b, 0x81c2c92eul + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+    Round(b, c, d, e, f, g, h, a, 0x92722c85ul + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+    Round(a, b, c, d, e, f, g, h, 0xa2bfe8a1ul + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+    Round(h, a, b, c, d, e, f, g, 0xa81a664bul + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+    Round(g, h, a, b, c, d, e, f, 0xc24b8b70ul + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+    Round(f, g, h, a, b, c, d, e, 0xc76c51a3ul + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+    Round(e, f, g, h, a, b, c, d, 0xd192e819ul + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+    Round(d, e, f, g, h, a, b, c, 0xd6990624ul + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+    Round(c, d, e, f, g, h, a, b, 0xf40e3585ul + (w14 += sigma1(w12) + w7 + sigma0(w15)));
+    Round(b, c, d, e, f, g, h, a, 0x106aa070ul + (w15 += sigma1(w13) + w8 + sigma0(w0)));
+    Round(a, b, c, d, e, f, g, h, 0x19a4c116ul + (w0 += sigma1(w14) + w9 + sigma0(w1)));
+    Round(h, a, b, c, d, e, f, g, 0x1e376c08ul + (w1 += sigma1(w15) + w10 + sigma0(w2)));
+    Round(g, h, a, b, c, d, e, f, 0x2748774cul + (w2 += sigma1(w0) + w11 + sigma0(w3)));
+    Round(f, g, h, a, b, c, d, e, 0x34b0bcb5ul + (w3 += sigma1(w1) + w12 + sigma0(w4)));
+    Round(e, f, g, h, a, b, c, d, 0x391c0cb3ul + (w4 += sigma1(w2) + w13 + sigma0(w5)));
+    Round(d, e, f, g, h, a, b, c, 0x4ed8aa4aul + (w5 += sigma1(w3) + w14 + sigma0(w6)));
+    Round(c, d, e, f, g, h, a, b, 0x5b9cca4ful + (w6 += sigma1(w4) + w15 + sigma0(w7)));
+    Round(b, c, d, e, f, g, h, a, 0x682e6ff3ul + (w7 += sigma1(w5) + w0 + sigma0(w8)));
+    Round(a, b, c, d, e, f, g, h, 0x748f82eeul + (w8 += sigma1(w6) + w1 + sigma0(w9)));
+    Round(h, a, b, c, d, e, f, g, 0x78a5636ful + (w9 += sigma1(w7) + w2 + sigma0(w10)));
+    Round(g, h, a, b, c, d, e, f, 0x84c87814ul + (w10 += sigma1(w8) + w3 + sigma0(w11)));
+    Round(f, g, h, a, b, c, d, e, 0x8cc70208ul + (w11 += sigma1(w9) + w4 + sigma0(w12)));
+    Round(e, f, g, h, a, b, c, d, 0x90befffaul + (w12 += sigma1(w10) + w5 + sigma0(w13)));
+    Round(d, e, f, g, h, a, b, c, 0xa4506cebul + (w13 += sigma1(w11) + w6 + sigma0(w14)));
+    Round(c, d, e, f, g, h, a, b, 0xbef9a3f7ul + (w14 + sigma1(w12) + w7 + sigma0(w15)));
+    Round(b, c, d, e, f, g, h, a, 0xc67178f2ul + (w15 + sigma1(w13) + w8 + sigma0(w0)));
+
+    // Output
+    WriteBE32(out + 0, a + 0x6a09e667ul);
+    WriteBE32(out + 4, b + 0xbb67ae85ul);
+    WriteBE32(out + 8, c + 0x3c6ef372ul);
+    WriteBE32(out + 12, d + 0xa54ff53aul);
+    WriteBE32(out + 16, e + 0x510e527ful);
+    WriteBE32(out + 20, f + 0x9b05688cul);
+    WriteBE32(out + 24, g + 0x1f83d9abul);
+    WriteBE32(out + 28, h + 0x5be0cd19ul);
+}
+
 } // namespace sha256
 
 typedef void (*TransformType)(uint32_t*, const unsigned char*, size_t);
+typedef void (*TransformD64Type)(unsigned char*, const unsigned char*);
+
+template<TransformType tr>
+void TransformD64Wrapper(unsigned char* out, const unsigned char* in)
+{
+    uint32_t s[8];
+    static const unsigned char padding1[64] = {
+        0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0
+    };
+    unsigned char buffer2[64] = {
+        0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0
+    };
+    sha256::Initialize(s);
+    tr(s, in, 1);
+    tr(s, padding1, 1);
+    WriteBE32(buffer2 + 0, s[0]);
+    WriteBE32(buffer2 + 4, s[1]);
+    WriteBE32(buffer2 + 8, s[2]);
+    WriteBE32(buffer2 + 12, s[3]);
+    WriteBE32(buffer2 + 16, s[4]);
+    WriteBE32(buffer2 + 20, s[5]);
+    WriteBE32(buffer2 + 24, s[6]);
+    WriteBE32(buffer2 + 28, s[7]);
+    sha256::Initialize(s);
+    tr(s, buffer2, 1);
+    WriteBE32(out + 0, s[0]);
+    WriteBE32(out + 4, s[1]);
+    WriteBE32(out + 8, s[2]);
+    WriteBE32(out + 12, s[3]);
+    WriteBE32(out + 16, s[4]);
+    WriteBE32(out + 20, s[5]);
+    WriteBE32(out + 24, s[6]);
+    WriteBE32(out + 28, s[7]);
+}
 
 bool SelfTest(TransformType tr) {
     static const unsigned char in1[65] = {0, 0x80};
@@ -173,22 +474,47 @@ bool SelfTest(TransformType tr) {
 }
 
 TransformType Transform = sha256::Transform;
+TransformD64Type TransformD64 = sha256::TransformD64;
+TransformD64Type TransformD64_4way = nullptr;
+TransformD64Type TransformD64_8way = nullptr;
 
+#if defined(USE_ASM) && (defined(__x86_64__) || defined(__amd64__))
+// We can't use cpuid.h's __get_cpuid as it does not support subleafs.
+void inline cpuid(uint32_t leaf, uint32_t subleaf, uint32_t& a, uint32_t& b, uint32_t& c, uint32_t& d)
+{
+  __asm__ ("cpuid" : "=a"(a), "=b"(b), "=c"(c), "=d"(d) : "0"(leaf), "2"(subleaf));
+}
+#endif
 } // namespace
 
+
 std::string SHA256AutoDetect()
 {
+    std::string ret = "standard";
 #if defined(USE_ASM) && (defined(__x86_64__) || defined(__amd64__))
     uint32_t eax, ebx, ecx, edx;
-    if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) && (ecx >> 19) & 1) {
+    cpuid(1, 0, eax, ebx, ecx, edx);
+    if ((ecx >> 19) & 1) {
         Transform = sha256_sse4::Transform;
-        assert(SelfTest(Transform));
-        return "sse4";
+        TransformD64 = TransformD64Wrapper<sha256_sse4::Transform>;
+#if defined(ENABLE_SSE41) && !defined(BUILD_BITCOIN_INTERNAL)
+        TransformD64_4way = sha256d64_sse41::Transform_4way;
+        ret = "sse4(1way+4way)";
+#if defined(ENABLE_AVX2) && !defined(BUILD_BITCOIN_INTERNAL)
+        cpuid(7, 0, eax, ebx, ecx, edx);
+        if ((ebx >> 5) & 1) {
+            TransformD64_8way = sha256d64_avx2::Transform_8way;
+            ret += ",avx2(8way)";
+        }
+#endif
+#else
+        ret = "sse4";
+#endif
     }
 #endif
 
     assert(SelfTest(Transform));
-    return "standard";
+    return ret;
 }
 
 ////// SHA-256
@@ -247,3 +573,29 @@ CSHA256& CSHA256::Reset()
     sha256::Initialize(s);
     return *this;
 }
+
+void SHA256D64(unsigned char* out, const unsigned char* in, size_t blocks)
+{
+    if (TransformD64_8way) {
+        while (blocks >= 8) {
+            TransformD64_8way(out, in);
+            out += 256;
+            in += 512;
+            blocks -= 8;
+        }
+    }
+    if (TransformD64_4way) {
+        while (blocks >= 4) {
+            TransformD64_4way(out, in);
+            out += 128;
+            in += 256;
+            blocks -= 4;
+        }
+    }
+    while (blocks) {
+        TransformD64(out, in);
+        out += 32;
+        in += 64;
+        --blocks;
+    }
+}
diff --git a/src/crypto/sha256.h b/src/crypto/sha256.h
index 51608af9c7..4d6812cc8c 100644
--- a/src/crypto/sha256.h
+++ b/src/crypto/sha256.h
@@ -31,4 +31,11 @@ public:
  */
 std::string SHA256AutoDetect();
 
+/** Compute multiple double-SHA256's of 64-byte blobs.
+ *  output:  pointer to a blocks*32 byte output buffer
+ *  input:   pointer to a blocks*64 byte input buffer
+ *  blocks:  the number of hashes to compute.
+ */
+void SHA256D64(unsigned char* output, const unsigned char* input, size_t blocks);
+
 #endif // BITCOIN_CRYPTO_SHA256_H
diff --git a/src/crypto/sha256_avx2.cpp b/src/crypto/sha256_avx2.cpp
new file mode 100644
index 0000000000..f45c1d4ab6
--- /dev/null
+++ b/src/crypto/sha256_avx2.cpp
@@ -0,0 +1,329 @@
+#ifdef ENABLE_AVX2
+
+#include <stdint.h>
+#if defined(_MSC_VER)
+#include <immintrin.h>
+#elif defined(__GNUC__)
+#include <x86intrin.h>
+#endif
+
+#include "crypto/sha256.h"
+#include "crypto/common.h"
+
+namespace sha256d64_avx2 {
+namespace {
+
+__m256i inline K(uint32_t x) { return _mm256_set1_epi32(x); }
+
+__m256i inline Add(__m256i x, __m256i y) { return _mm256_add_epi32(x, y); }
+__m256i inline Add(__m256i x, __m256i y, __m256i z) { return Add(Add(x, y), z); }
+__m256i inline Add(__m256i x, __m256i y, __m256i z, __m256i w) { return Add(Add(x, y), Add(z, w)); }
+__m256i inline Add(__m256i x, __m256i y, __m256i z, __m256i w, __m256i v) { return Add(Add(x, y, z), Add(w, v)); }
+__m256i inline Inc(__m256i& x, __m256i y) { x = Add(x, y); return x; }
+__m256i inline Inc(__m256i& x, __m256i y, __m256i z) { x = Add(x, y, z); return x; }
+__m256i inline Inc(__m256i& x, __m256i y, __m256i z, __m256i w) { x = Add(x, y, z, w); return x; }
+__m256i inline Xor(__m256i x, __m256i y) { return _mm256_xor_si256(x, y); }
+__m256i inline Xor(__m256i x, __m256i y, __m256i z) { return Xor(Xor(x, y), z); }
+__m256i inline Or(__m256i x, __m256i y) { return _mm256_or_si256(x, y); }
+__m256i inline And(__m256i x, __m256i y) { return _mm256_and_si256(x, y); }
+__m256i inline ShR(__m256i x, int n) { return _mm256_srli_epi32(x, n); }
+__m256i inline ShL(__m256i x, int n) { return _mm256_slli_epi32(x, n); }
+
+__m256i inline Ch(__m256i x, __m256i y, __m256i z) { return Xor(z, And(x, Xor(y, z))); }
+__m256i inline Maj(__m256i x, __m256i y, __m256i z) { return Or(And(x, y), And(z, Or(x, y))); }
+__m256i inline Sigma0(__m256i x) { return Xor(Or(ShR(x, 2), ShL(x, 30)), Or(ShR(x, 13), ShL(x, 19)), Or(ShR(x, 22), ShL(x, 10))); }
+__m256i inline Sigma1(__m256i x) { return Xor(Or(ShR(x, 6), ShL(x, 26)), Or(ShR(x, 11), ShL(x, 21)), Or(ShR(x, 25), ShL(x, 7))); }
+__m256i inline sigma0(__m256i x) { return Xor(Or(ShR(x, 7), ShL(x, 25)), Or(ShR(x, 18), ShL(x, 14)), ShR(x, 3)); }
+__m256i inline sigma1(__m256i x) { return Xor(Or(ShR(x, 17), ShL(x, 15)), Or(ShR(x, 19), ShL(x, 13)), ShR(x, 10)); }
+
+/** One round of SHA-256. */
+void inline __attribute__((always_inline)) Round(__m256i a, __m256i b, __m256i c, __m256i& d, __m256i e, __m256i f, __m256i g, __m256i& h, __m256i k)
+{
+    __m256i t1 = Add(h, Sigma1(e), Ch(e, f, g), k);
+    __m256i t2 = Add(Sigma0(a), Maj(a, b, c));
+    d = Add(d, t1);
+    h = Add(t1, t2);
+}
+
+__m256i inline Read8(const unsigned char* chunk, int offset) {
+    __m256i ret = _mm256_set_epi32(
+        ReadLE32(chunk + 0 + offset),
+        ReadLE32(chunk + 64 + offset),
+        ReadLE32(chunk + 128 + offset),
+        ReadLE32(chunk + 192 + offset),
+        ReadLE32(chunk + 256 + offset),
+        ReadLE32(chunk + 320 + offset),
+        ReadLE32(chunk + 384 + offset),
+        ReadLE32(chunk + 448 + offset)
+    );
+    return _mm256_shuffle_epi8(ret, _mm256_set_epi32(0x0C0D0E0FUL, 0x08090A0BUL, 0x04050607UL, 0x00010203UL, 0x0C0D0E0FUL, 0x08090A0BUL, 0x04050607UL, 0x00010203UL));
+}
+
+void inline Write8(unsigned char* out, int offset, __m256i v) {
+    v = _mm256_shuffle_epi8(v, _mm256_set_epi32(0x0C0D0E0FUL, 0x08090A0BUL, 0x04050607UL, 0x00010203UL, 0x0C0D0E0FUL, 0x08090A0BUL, 0x04050607UL, 0x00010203UL));
+    WriteLE32(out + 0 + offset, _mm256_extract_epi32(v, 7));
+    WriteLE32(out + 32 + offset, _mm256_extract_epi32(v, 6));
+    WriteLE32(out + 64 + offset, _mm256_extract_epi32(v, 5));
+    WriteLE32(out + 96 + offset, _mm256_extract_epi32(v, 4));
+    WriteLE32(out + 128 + offset, _mm256_extract_epi32(v, 3));
+    WriteLE32(out + 160 + offset, _mm256_extract_epi32(v, 2));
+    WriteLE32(out + 192 + offset, _mm256_extract_epi32(v, 1));
+    WriteLE32(out + 224 + offset, _mm256_extract_epi32(v, 0));
+}
+
+}
+
+void Transform_8way(unsigned char* out, const unsigned char* in)
+{
+    // Transform 1
+    __m256i a = K(0x6a09e667ul);
+    __m256i b = K(0xbb67ae85ul);
+    __m256i c = K(0x3c6ef372ul);
+    __m256i d = K(0xa54ff53aul);
+    __m256i e = K(0x510e527ful);
+    __m256i f = K(0x9b05688cul);
+    __m256i g = K(0x1f83d9abul);
+    __m256i h = K(0x5be0cd19ul);
+
+    __m256i w0, w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13, w14, w15;
+
+    Round(a, b, c, d, e, f, g, h, Add(K(0x428a2f98ul), w0 = Read8(in, 0)));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x71374491ul), w1 = Read8(in, 4)));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb5c0fbcful), w2 = Read8(in, 8)));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xe9b5dba5ul), w3 = Read8(in, 12)));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x3956c25bul), w4 = Read8(in, 16)));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x59f111f1ul), w5 = Read8(in, 20)));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x923f82a4ul), w6 = Read8(in, 24)));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xab1c5ed5ul), w7 = Read8(in, 28)));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xd807aa98ul), w8 = Read8(in, 32)));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x12835b01ul), w9 = Read8(in, 36)));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x243185beul), w10 = Read8(in, 40)));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x550c7dc3ul), w11 = Read8(in, 44)));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x72be5d74ul), w12 = Read8(in, 48)));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x80deb1feul), w13 = Read8(in, 52)));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x9bdc06a7ul), w14 = Read8(in, 56)));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xc19bf174ul), w15 = Read8(in, 60)));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xe49b69c1ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xefbe4786ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x0fc19dc6ul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x240ca1ccul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x2de92c6ful), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4a7484aaul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5cb0a9dcul), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x76f988daul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x983e5152ul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa831c66dul), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb00327c8ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xbf597fc7ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xc6e00bf3ul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd5a79147ul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x06ca6351ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x14292967ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x27b70a85ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x2e1b2138ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x4d2c6dfcul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x53380d13ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x650a7354ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x766a0abbul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x81c2c92eul), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x92722c85ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xa2bfe8a1ul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa81a664bul), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xc24b8b70ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xc76c51a3ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xd192e819ul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd6990624ul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xf40e3585ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x106aa070ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x19a4c116ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x1e376c08ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x2748774cul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x34b0bcb5ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x391c0cb3ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4ed8aa4aul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5b9cca4ful), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x682e6ff3ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x748f82eeul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x78a5636ful), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x84c87814ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x8cc70208ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x90befffaul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xa4506cebul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xbef9a3f7ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xc67178f2ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+
+    a = Add(a, K(0x6a09e667ul));
+    b = Add(b, K(0xbb67ae85ul));
+    c = Add(c, K(0x3c6ef372ul));
+    d = Add(d, K(0xa54ff53aul));
+    e = Add(e, K(0x510e527ful));
+    f = Add(f, K(0x9b05688cul));
+    g = Add(g, K(0x1f83d9abul));
+    h = Add(h, K(0x5be0cd19ul));
+
+    __m256i t0 = a, t1 = b, t2 = c, t3 = d, t4 = e, t5 = f, t6 = g, t7 = h;
+
+    // Transform 2
+    Round(a, b, c, d, e, f, g, h, K(0xc28a2f98ul));
+    Round(h, a, b, c, d, e, f, g, K(0x71374491ul));
+    Round(g, h, a, b, c, d, e, f, K(0xb5c0fbcful));
+    Round(f, g, h, a, b, c, d, e, K(0xe9b5dba5ul));
+    Round(e, f, g, h, a, b, c, d, K(0x3956c25bul));
+    Round(d, e, f, g, h, a, b, c, K(0x59f111f1ul));
+    Round(c, d, e, f, g, h, a, b, K(0x923f82a4ul));
+    Round(b, c, d, e, f, g, h, a, K(0xab1c5ed5ul));
+    Round(a, b, c, d, e, f, g, h, K(0xd807aa98ul));
+    Round(h, a, b, c, d, e, f, g, K(0x12835b01ul));
+    Round(g, h, a, b, c, d, e, f, K(0x243185beul));
+    Round(f, g, h, a, b, c, d, e, K(0x550c7dc3ul));
+    Round(e, f, g, h, a, b, c, d, K(0x72be5d74ul));
+    Round(d, e, f, g, h, a, b, c, K(0x80deb1feul));
+    Round(c, d, e, f, g, h, a, b, K(0x9bdc06a7ul));
+    Round(b, c, d, e, f, g, h, a, K(0xc19bf374ul));
+    Round(a, b, c, d, e, f, g, h, K(0x649b69c1ul));
+    Round(h, a, b, c, d, e, f, g, K(0xf0fe4786ul));
+    Round(g, h, a, b, c, d, e, f, K(0x0fe1edc6ul));
+    Round(f, g, h, a, b, c, d, e, K(0x240cf254ul));
+    Round(e, f, g, h, a, b, c, d, K(0x4fe9346ful));
+    Round(d, e, f, g, h, a, b, c, K(0x6cc984beul));
+    Round(c, d, e, f, g, h, a, b, K(0x61b9411eul));
+    Round(b, c, d, e, f, g, h, a, K(0x16f988faul));
+    Round(a, b, c, d, e, f, g, h, K(0xf2c65152ul));
+    Round(h, a, b, c, d, e, f, g, K(0xa88e5a6dul));
+    Round(g, h, a, b, c, d, e, f, K(0xb019fc65ul));
+    Round(f, g, h, a, b, c, d, e, K(0xb9d99ec7ul));
+    Round(e, f, g, h, a, b, c, d, K(0x9a1231c3ul));
+    Round(d, e, f, g, h, a, b, c, K(0xe70eeaa0ul));
+    Round(c, d, e, f, g, h, a, b, K(0xfdb1232bul));
+    Round(b, c, d, e, f, g, h, a, K(0xc7353eb0ul));
+    Round(a, b, c, d, e, f, g, h, K(0x3069bad5ul));
+    Round(h, a, b, c, d, e, f, g, K(0xcb976d5ful));
+    Round(g, h, a, b, c, d, e, f, K(0x5a0f118ful));
+    Round(f, g, h, a, b, c, d, e, K(0xdc1eeefdul));
+    Round(e, f, g, h, a, b, c, d, K(0x0a35b689ul));
+    Round(d, e, f, g, h, a, b, c, K(0xde0b7a04ul));
+    Round(c, d, e, f, g, h, a, b, K(0x58f4ca9dul));
+    Round(b, c, d, e, f, g, h, a, K(0xe15d5b16ul));
+    Round(a, b, c, d, e, f, g, h, K(0x007f3e86ul));
+    Round(h, a, b, c, d, e, f, g, K(0x37088980ul));
+    Round(g, h, a, b, c, d, e, f, K(0xa507ea32ul));
+    Round(f, g, h, a, b, c, d, e, K(0x6fab9537ul));
+    Round(e, f, g, h, a, b, c, d, K(0x17406110ul));
+    Round(d, e, f, g, h, a, b, c, K(0x0d8cd6f1ul));
+    Round(c, d, e, f, g, h, a, b, K(0xcdaa3b6dul));
+    Round(b, c, d, e, f, g, h, a, K(0xc0bbbe37ul));
+    Round(a, b, c, d, e, f, g, h, K(0x83613bdaul));
+    Round(h, a, b, c, d, e, f, g, K(0xdb48a363ul));
+    Round(g, h, a, b, c, d, e, f, K(0x0b02e931ul));
+    Round(f, g, h, a, b, c, d, e, K(0x6fd15ca7ul));
+    Round(e, f, g, h, a, b, c, d, K(0x521afacaul));
+    Round(d, e, f, g, h, a, b, c, K(0x31338431ul));
+    Round(c, d, e, f, g, h, a, b, K(0x6ed41a95ul));
+    Round(b, c, d, e, f, g, h, a, K(0x6d437890ul));
+    Round(a, b, c, d, e, f, g, h, K(0xc39c91f2ul));
+    Round(h, a, b, c, d, e, f, g, K(0x9eccabbdul));
+    Round(g, h, a, b, c, d, e, f, K(0xb5c9a0e6ul));
+    Round(f, g, h, a, b, c, d, e, K(0x532fb63cul));
+    Round(e, f, g, h, a, b, c, d, K(0xd2c741c6ul));
+    Round(d, e, f, g, h, a, b, c, K(0x07237ea3ul));
+    Round(c, d, e, f, g, h, a, b, K(0xa4954b68ul));
+    Round(b, c, d, e, f, g, h, a, K(0x4c191d76ul));
+
+    w0 = Add(t0, a);
+    w1 = Add(t1, b);
+    w2 = Add(t2, c);
+    w3 = Add(t3, d);
+    w4 = Add(t4, e);
+    w5 = Add(t5, f);
+    w6 = Add(t6, g);
+    w7 = Add(t7, h);
+
+    // Transform 3
+    a = K(0x6a09e667ul);
+    b = K(0xbb67ae85ul);
+    c = K(0x3c6ef372ul);
+    d = K(0xa54ff53aul);
+    e = K(0x510e527ful);
+    f = K(0x9b05688cul);
+    g = K(0x1f83d9abul);
+    h = K(0x5be0cd19ul);
+
+    Round(a, b, c, d, e, f, g, h, Add(K(0x428a2f98ul), w0));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x71374491ul), w1));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb5c0fbcful), w2));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xe9b5dba5ul), w3));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x3956c25bul), w4));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x59f111f1ul), w5));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x923f82a4ul), w6));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xab1c5ed5ul), w7));
+    Round(a, b, c, d, e, f, g, h, K(0x5807aa98ul));
+    Round(h, a, b, c, d, e, f, g, K(0x12835b01ul));
+    Round(g, h, a, b, c, d, e, f, K(0x243185beul));
+    Round(f, g, h, a, b, c, d, e, K(0x550c7dc3ul));
+    Round(e, f, g, h, a, b, c, d, K(0x72be5d74ul));
+    Round(d, e, f, g, h, a, b, c, K(0x80deb1feul));
+    Round(c, d, e, f, g, h, a, b, K(0x9bdc06a7ul));
+    Round(b, c, d, e, f, g, h, a, K(0xc19bf274ul));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xe49b69c1ul), Inc(w0, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xefbe4786ul), Inc(w1, K(0xa00000ul), sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x0fc19dc6ul), Inc(w2, sigma1(w0), sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x240ca1ccul), Inc(w3, sigma1(w1), sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x2de92c6ful), Inc(w4, sigma1(w2), sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4a7484aaul), Inc(w5, sigma1(w3), sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5cb0a9dcul), Inc(w6, sigma1(w4), K(0x100ul), sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x76f988daul), Inc(w7, sigma1(w5), w0, K(0x11002000ul))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x983e5152ul), w8 = Add(K(0x80000000ul), sigma1(w6), w1)));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa831c66dul), w9 = Add(sigma1(w7), w2)));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb00327c8ul), w10 = Add(sigma1(w8), w3)));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xbf597fc7ul), w11 = Add(sigma1(w9), w4)));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xc6e00bf3ul), w12 = Add(sigma1(w10), w5)));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd5a79147ul), w13 = Add(sigma1(w11), w6)));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x06ca6351ul), w14 = Add(sigma1(w12), w7, K(0x400022ul))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x14292967ul), w15 = Add(K(0x100ul), sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x27b70a85ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x2e1b2138ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x4d2c6dfcul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x53380d13ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x650a7354ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x766a0abbul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x81c2c92eul), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x92722c85ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xa2bfe8a1ul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa81a664bul), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xc24b8b70ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xc76c51a3ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xd192e819ul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd6990624ul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xf40e3585ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x106aa070ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x19a4c116ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x1e376c08ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x2748774cul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x34b0bcb5ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x391c0cb3ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4ed8aa4aul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5b9cca4ful), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x682e6ff3ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x748f82eeul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x78a5636ful), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x84c87814ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x8cc70208ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x90befffaul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xa4506cebul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xbef9a3f7ul), w14, sigma1(w12), w7, sigma0(w15)));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xc67178f2ul), w15, sigma1(w13), w8, sigma0(w0)));
+
+    // Output
+    Write8(out, 0, Add(a, K(0x6a09e667ul)));
+    Write8(out, 4, Add(b, K(0xbb67ae85ul)));
+    Write8(out, 8, Add(c, K(0x3c6ef372ul)));
+    Write8(out, 12, Add(d, K(0xa54ff53aul)));
+    Write8(out, 16, Add(e, K(0x510e527ful)));
+    Write8(out, 20, Add(f, K(0x9b05688cul)));
+    Write8(out, 24, Add(g, K(0x1f83d9abul)));
+    Write8(out, 28, Add(h, K(0x5be0cd19ul)));
+}
+
+}
+
+#endif
diff --git a/src/crypto/sha256_sse41.cpp b/src/crypto/sha256_sse41.cpp
new file mode 100644
index 0000000000..a11d658c70
--- /dev/null
+++ b/src/crypto/sha256_sse41.cpp
@@ -0,0 +1,321 @@
+#ifdef ENABLE_SSE41
+
+#include <stdint.h>
+#if defined(_MSC_VER)
+#include <immintrin.h>
+#elif defined(__GNUC__)
+#include <x86intrin.h>
+#endif
+
+#include "crypto/sha256.h"
+#include "crypto/common.h"
+
+namespace sha256d64_sse41 {
+namespace {
+
+__m128i inline K(uint32_t x) { return _mm_set1_epi32(x); }
+
+__m128i inline Add(__m128i x, __m128i y) { return _mm_add_epi32(x, y); }
+__m128i inline Add(__m128i x, __m128i y, __m128i z) { return Add(Add(x, y), z); }
+__m128i inline Add(__m128i x, __m128i y, __m128i z, __m128i w) { return Add(Add(x, y), Add(z, w)); }
+__m128i inline Add(__m128i x, __m128i y, __m128i z, __m128i w, __m128i v) { return Add(Add(x, y, z), Add(w, v)); }
+__m128i inline Inc(__m128i& x, __m128i y) { x = Add(x, y); return x; }
+__m128i inline Inc(__m128i& x, __m128i y, __m128i z) { x = Add(x, y, z); return x; }
+__m128i inline Inc(__m128i& x, __m128i y, __m128i z, __m128i w) { x = Add(x, y, z, w); return x; }
+__m128i inline Xor(__m128i x, __m128i y) { return _mm_xor_si128(x, y); }
+__m128i inline Xor(__m128i x, __m128i y, __m128i z) { return Xor(Xor(x, y), z); }
+__m128i inline Or(__m128i x, __m128i y) { return _mm_or_si128(x, y); }
+__m128i inline And(__m128i x, __m128i y) { return _mm_and_si128(x, y); }
+__m128i inline ShR(__m128i x, int n) { return _mm_srli_epi32(x, n); }
+__m128i inline ShL(__m128i x, int n) { return _mm_slli_epi32(x, n); }
+
+__m128i inline Ch(__m128i x, __m128i y, __m128i z) { return Xor(z, And(x, Xor(y, z))); }
+__m128i inline Maj(__m128i x, __m128i y, __m128i z) { return Or(And(x, y), And(z, Or(x, y))); }
+__m128i inline Sigma0(__m128i x) { return Xor(Or(ShR(x, 2), ShL(x, 30)), Or(ShR(x, 13), ShL(x, 19)), Or(ShR(x, 22), ShL(x, 10))); }
+__m128i inline Sigma1(__m128i x) { return Xor(Or(ShR(x, 6), ShL(x, 26)), Or(ShR(x, 11), ShL(x, 21)), Or(ShR(x, 25), ShL(x, 7))); }
+__m128i inline sigma0(__m128i x) { return Xor(Or(ShR(x, 7), ShL(x, 25)), Or(ShR(x, 18), ShL(x, 14)), ShR(x, 3)); }
+__m128i inline sigma1(__m128i x) { return Xor(Or(ShR(x, 17), ShL(x, 15)), Or(ShR(x, 19), ShL(x, 13)), ShR(x, 10)); }
+
+/** One round of SHA-256. */
+void inline __attribute__((always_inline)) Round(__m128i a, __m128i b, __m128i c, __m128i& d, __m128i e, __m128i f, __m128i g, __m128i& h, __m128i k)
+{
+    __m128i t1 = Add(h, Sigma1(e), Ch(e, f, g), k);
+    __m128i t2 = Add(Sigma0(a), Maj(a, b, c));
+    d = Add(d, t1);
+    h = Add(t1, t2);
+}
+
+__m128i inline Read4(const unsigned char* chunk, int offset) {
+    __m128i ret = _mm_set_epi32(
+        ReadLE32(chunk + 0 + offset),
+        ReadLE32(chunk + 64 + offset),
+        ReadLE32(chunk + 128 + offset),
+        ReadLE32(chunk + 192 + offset)
+    );
+    return _mm_shuffle_epi8(ret, _mm_set_epi32(0x0C0D0E0FUL, 0x08090A0BUL, 0x04050607UL, 0x00010203UL));
+}
+
+void inline Write4(unsigned char* out, int offset, __m128i v) {
+    v = _mm_shuffle_epi8(v, _mm_set_epi32(0x0C0D0E0FUL, 0x08090A0BUL, 0x04050607UL, 0x00010203UL));
+    WriteLE32(out + 0 + offset, _mm_extract_epi32(v, 3));
+    WriteLE32(out + 32 + offset, _mm_extract_epi32(v, 2));
+    WriteLE32(out + 64 + offset, _mm_extract_epi32(v, 1));
+    WriteLE32(out + 96 + offset, _mm_extract_epi32(v, 0));
+}
+
+}
+
+void Transform_4way(unsigned char* out, const unsigned char* in)
+{
+    // Transform 1
+    __m128i a = K(0x6a09e667ul);
+    __m128i b = K(0xbb67ae85ul);
+    __m128i c = K(0x3c6ef372ul);
+    __m128i d = K(0xa54ff53aul);
+    __m128i e = K(0x510e527ful);
+    __m128i f = K(0x9b05688cul);
+    __m128i g = K(0x1f83d9abul);
+    __m128i h = K(0x5be0cd19ul);
+
+    __m128i w0, w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13, w14, w15;
+
+    Round(a, b, c, d, e, f, g, h, Add(K(0x428a2f98ul), w0 = Read4(in, 0)));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x71374491ul), w1 = Read4(in, 4)));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb5c0fbcful), w2 = Read4(in, 8)));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xe9b5dba5ul), w3 = Read4(in, 12)));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x3956c25bul), w4 = Read4(in, 16)));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x59f111f1ul), w5 = Read4(in, 20)));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x923f82a4ul), w6 = Read4(in, 24)));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xab1c5ed5ul), w7 = Read4(in, 28)));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xd807aa98ul), w8 = Read4(in, 32)));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x12835b01ul), w9 = Read4(in, 36)));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x243185beul), w10 = Read4(in, 40)));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x550c7dc3ul), w11 = Read4(in, 44)));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x72be5d74ul), w12 = Read4(in, 48)));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x80deb1feul), w13 = Read4(in, 52)));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x9bdc06a7ul), w14 = Read4(in, 56)));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xc19bf174ul), w15 = Read4(in, 60)));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xe49b69c1ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xefbe4786ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x0fc19dc6ul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x240ca1ccul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x2de92c6ful), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4a7484aaul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5cb0a9dcul), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x76f988daul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x983e5152ul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa831c66dul), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb00327c8ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xbf597fc7ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xc6e00bf3ul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd5a79147ul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x06ca6351ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x14292967ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x27b70a85ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x2e1b2138ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x4d2c6dfcul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x53380d13ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x650a7354ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x766a0abbul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x81c2c92eul), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x92722c85ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xa2bfe8a1ul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa81a664bul), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xc24b8b70ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xc76c51a3ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xd192e819ul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd6990624ul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xf40e3585ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x106aa070ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x19a4c116ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x1e376c08ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x2748774cul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x34b0bcb5ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x391c0cb3ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4ed8aa4aul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5b9cca4ful), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x682e6ff3ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x748f82eeul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x78a5636ful), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x84c87814ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x8cc70208ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x90befffaul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xa4506cebul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xbef9a3f7ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xc67178f2ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+
+    a = Add(a, K(0x6a09e667ul));
+    b = Add(b, K(0xbb67ae85ul));
+    c = Add(c, K(0x3c6ef372ul));
+    d = Add(d, K(0xa54ff53aul));
+    e = Add(e, K(0x510e527ful));
+    f = Add(f, K(0x9b05688cul));
+    g = Add(g, K(0x1f83d9abul));
+    h = Add(h, K(0x5be0cd19ul));
+
+    __m128i t0 = a, t1 = b, t2 = c, t3 = d, t4 = e, t5 = f, t6 = g, t7 = h;
+
+    // Transform 2
+    Round(a, b, c, d, e, f, g, h, K(0xc28a2f98ul));
+    Round(h, a, b, c, d, e, f, g, K(0x71374491ul));
+    Round(g, h, a, b, c, d, e, f, K(0xb5c0fbcful));
+    Round(f, g, h, a, b, c, d, e, K(0xe9b5dba5ul));
+    Round(e, f, g, h, a, b, c, d, K(0x3956c25bul));
+    Round(d, e, f, g, h, a, b, c, K(0x59f111f1ul));
+    Round(c, d, e, f, g, h, a, b, K(0x923f82a4ul));
+    Round(b, c, d, e, f, g, h, a, K(0xab1c5ed5ul));
+    Round(a, b, c, d, e, f, g, h, K(0xd807aa98ul));
+    Round(h, a, b, c, d, e, f, g, K(0x12835b01ul));
+    Round(g, h, a, b, c, d, e, f, K(0x243185beul));
+    Round(f, g, h, a, b, c, d, e, K(0x550c7dc3ul));
+    Round(e, f, g, h, a, b, c, d, K(0x72be5d74ul));
+    Round(d, e, f, g, h, a, b, c, K(0x80deb1feul));
+    Round(c, d, e, f, g, h, a, b, K(0x9bdc06a7ul));
+    Round(b, c, d, e, f, g, h, a, K(0xc19bf374ul));
+    Round(a, b, c, d, e, f, g, h, K(0x649b69c1ul));
+    Round(h, a, b, c, d, e, f, g, K(0xf0fe4786ul));
+    Round(g, h, a, b, c, d, e, f, K(0x0fe1edc6ul));
+    Round(f, g, h, a, b, c, d, e, K(0x240cf254ul));
+    Round(e, f, g, h, a, b, c, d, K(0x4fe9346ful));
+    Round(d, e, f, g, h, a, b, c, K(0x6cc984beul));
+    Round(c, d, e, f, g, h, a, b, K(0x61b9411eul));
+    Round(b, c, d, e, f, g, h, a, K(0x16f988faul));
+    Round(a, b, c, d, e, f, g, h, K(0xf2c65152ul));
+    Round(h, a, b, c, d, e, f, g, K(0xa88e5a6dul));
+    Round(g, h, a, b, c, d, e, f, K(0xb019fc65ul));
+    Round(f, g, h, a, b, c, d, e, K(0xb9d99ec7ul));
+    Round(e, f, g, h, a, b, c, d, K(0x9a1231c3ul));
+    Round(d, e, f, g, h, a, b, c, K(0xe70eeaa0ul));
+    Round(c, d, e, f, g, h, a, b, K(0xfdb1232bul));
+    Round(b, c, d, e, f, g, h, a, K(0xc7353eb0ul));
+    Round(a, b, c, d, e, f, g, h, K(0x3069bad5ul));
+    Round(h, a, b, c, d, e, f, g, K(0xcb976d5ful));
+    Round(g, h, a, b, c, d, e, f, K(0x5a0f118ful));
+    Round(f, g, h, a, b, c, d, e, K(0xdc1eeefdul));
+    Round(e, f, g, h, a, b, c, d, K(0x0a35b689ul));
+    Round(d, e, f, g, h, a, b, c, K(0xde0b7a04ul));
+    Round(c, d, e, f, g, h, a, b, K(0x58f4ca9dul));
+    Round(b, c, d, e, f, g, h, a, K(0xe15d5b16ul));
+    Round(a, b, c, d, e, f, g, h, K(0x007f3e86ul));
+    Round(h, a, b, c, d, e, f, g, K(0x37088980ul));
+    Round(g, h, a, b, c, d, e, f, K(0xa507ea32ul));
+    Round(f, g, h, a, b, c, d, e, K(0x6fab9537ul));
+    Round(e, f, g, h, a, b, c, d, K(0x17406110ul));
+    Round(d, e, f, g, h, a, b, c, K(0x0d8cd6f1ul));
+    Round(c, d, e, f, g, h, a, b, K(0xcdaa3b6dul));
+    Round(b, c, d, e, f, g, h, a, K(0xc0bbbe37ul));
+    Round(a, b, c, d, e, f, g, h, K(0x83613bdaul));
+    Round(h, a, b, c, d, e, f, g, K(0xdb48a363ul));
+    Round(g, h, a, b, c, d, e, f, K(0x0b02e931ul));
+    Round(f, g, h, a, b, c, d, e, K(0x6fd15ca7ul));
+    Round(e, f, g, h, a, b, c, d, K(0x521afacaul));
+    Round(d, e, f, g, h, a, b, c, K(0x31338431ul));
+    Round(c, d, e, f, g, h, a, b, K(0x6ed41a95ul));
+    Round(b, c, d, e, f, g, h, a, K(0x6d437890ul));
+    Round(a, b, c, d, e, f, g, h, K(0xc39c91f2ul));
+    Round(h, a, b, c, d, e, f, g, K(0x9eccabbdul));
+    Round(g, h, a, b, c, d, e, f, K(0xb5c9a0e6ul));
+    Round(f, g, h, a, b, c, d, e, K(0x532fb63cul));
+    Round(e, f, g, h, a, b, c, d, K(0xd2c741c6ul));
+    Round(d, e, f, g, h, a, b, c, K(0x07237ea3ul));
+    Round(c, d, e, f, g, h, a, b, K(0xa4954b68ul));
+    Round(b, c, d, e, f, g, h, a, K(0x4c191d76ul));
+
+    w0 = Add(t0, a);
+    w1 = Add(t1, b);
+    w2 = Add(t2, c);
+    w3 = Add(t3, d);
+    w4 = Add(t4, e);
+    w5 = Add(t5, f);
+    w6 = Add(t6, g);
+    w7 = Add(t7, h);
+
+    // Transform 3
+    a = K(0x6a09e667ul);
+    b = K(0xbb67ae85ul);
+    c = K(0x3c6ef372ul);
+    d = K(0xa54ff53aul);
+    e = K(0x510e527ful);
+    f = K(0x9b05688cul);
+    g = K(0x1f83d9abul);
+    h = K(0x5be0cd19ul);
+
+    Round(a, b, c, d, e, f, g, h, Add(K(0x428a2f98ul), w0));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x71374491ul), w1));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb5c0fbcful), w2));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xe9b5dba5ul), w3));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x3956c25bul), w4));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x59f111f1ul), w5));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x923f82a4ul), w6));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xab1c5ed5ul), w7));
+    Round(a, b, c, d, e, f, g, h, K(0x5807aa98ul));
+    Round(h, a, b, c, d, e, f, g, K(0x12835b01ul));
+    Round(g, h, a, b, c, d, e, f, K(0x243185beul));
+    Round(f, g, h, a, b, c, d, e, K(0x550c7dc3ul));
+    Round(e, f, g, h, a, b, c, d, K(0x72be5d74ul));
+    Round(d, e, f, g, h, a, b, c, K(0x80deb1feul));
+    Round(c, d, e, f, g, h, a, b, K(0x9bdc06a7ul));
+    Round(b, c, d, e, f, g, h, a, K(0xc19bf274ul));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xe49b69c1ul), Inc(w0, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xefbe4786ul), Inc(w1, K(0xa00000ul), sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x0fc19dc6ul), Inc(w2, sigma1(w0), sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x240ca1ccul), Inc(w3, sigma1(w1), sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x2de92c6ful), Inc(w4, sigma1(w2), sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4a7484aaul), Inc(w5, sigma1(w3), sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5cb0a9dcul), Inc(w6, sigma1(w4), K(0x100ul), sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x76f988daul), Inc(w7, sigma1(w5), w0, K(0x11002000ul))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x983e5152ul), w8 = Add(K(0x80000000ul), sigma1(w6), w1)));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa831c66dul), w9 = Add(sigma1(w7), w2)));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xb00327c8ul), w10 = Add(sigma1(w8), w3)));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xbf597fc7ul), w11 = Add(sigma1(w9), w4)));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xc6e00bf3ul), w12 = Add(sigma1(w10), w5)));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd5a79147ul), w13 = Add(sigma1(w11), w6)));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x06ca6351ul), w14 = Add(sigma1(w12), w7, K(0x400022ul))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x14292967ul), w15 = Add(K(0x100ul), sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x27b70a85ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x2e1b2138ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x4d2c6dfcul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x53380d13ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x650a7354ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x766a0abbul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x81c2c92eul), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x92722c85ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0xa2bfe8a1ul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0xa81a664bul), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0xc24b8b70ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0xc76c51a3ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0xd192e819ul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xd6990624ul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xf40e3585ul), Inc(w14, sigma1(w12), w7, sigma0(w15))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x106aa070ul), Inc(w15, sigma1(w13), w8, sigma0(w0))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x19a4c116ul), Inc(w0, sigma1(w14), w9, sigma0(w1))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x1e376c08ul), Inc(w1, sigma1(w15), w10, sigma0(w2))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x2748774cul), Inc(w2, sigma1(w0), w11, sigma0(w3))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x34b0bcb5ul), Inc(w3, sigma1(w1), w12, sigma0(w4))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x391c0cb3ul), Inc(w4, sigma1(w2), w13, sigma0(w5))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0x4ed8aa4aul), Inc(w5, sigma1(w3), w14, sigma0(w6))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0x5b9cca4ful), Inc(w6, sigma1(w4), w15, sigma0(w7))));
+    Round(b, c, d, e, f, g, h, a, Add(K(0x682e6ff3ul), Inc(w7, sigma1(w5), w0, sigma0(w8))));
+    Round(a, b, c, d, e, f, g, h, Add(K(0x748f82eeul), Inc(w8, sigma1(w6), w1, sigma0(w9))));
+    Round(h, a, b, c, d, e, f, g, Add(K(0x78a5636ful), Inc(w9, sigma1(w7), w2, sigma0(w10))));
+    Round(g, h, a, b, c, d, e, f, Add(K(0x84c87814ul), Inc(w10, sigma1(w8), w3, sigma0(w11))));
+    Round(f, g, h, a, b, c, d, e, Add(K(0x8cc70208ul), Inc(w11, sigma1(w9), w4, sigma0(w12))));
+    Round(e, f, g, h, a, b, c, d, Add(K(0x90befffaul), Inc(w12, sigma1(w10), w5, sigma0(w13))));
+    Round(d, e, f, g, h, a, b, c, Add(K(0xa4506cebul), Inc(w13, sigma1(w11), w6, sigma0(w14))));
+    Round(c, d, e, f, g, h, a, b, Add(K(0xbef9a3f7ul), w14, sigma1(w12), w7, sigma0(w15)));
+    Round(b, c, d, e, f, g, h, a, Add(K(0xc67178f2ul), w15, sigma1(w13), w8, sigma0(w0)));
+
+    // Output
+    Write4(out, 0, Add(a, K(0x6a09e667ul)));
+    Write4(out, 4, Add(b, K(0xbb67ae85ul)));
+    Write4(out, 8, Add(c, K(0x3c6ef372ul)));
+    Write4(out, 12, Add(d, K(0xa54ff53aul)));
+    Write4(out, 16, Add(e, K(0x510e527ful)));
+    Write4(out, 20, Add(f, K(0x9b05688cul)));
+    Write4(out, 24, Add(g, K(0x1f83d9abul)));
+    Write4(out, 28, Add(h, K(0x5be0cd19ul)));
+}
+
+}
+
+#endif
diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
index e67e10cd56..1e8cc1c2ef 100644
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -767,4 +767,20 @@ BOOST_AUTO_TEST_CASE(countbits_tests)
     }
 }
 
+BOOST_AUTO_TEST_CASE(sha256d64)
+{
+    for (int i = 0; i <= 32; ++i) {
+        unsigned char in[64 * 32];
+        unsigned char out1[32 * 32], out2[32 * 32];
+        for (int j = 0; j < 64 * i; ++j) {
+            in[j] = InsecureRandBits(8);
+        }
+        for (int j = 0; j < i; ++j) {
+            CHash256().Write(in + 64 * j, 64).Finalize(out1 + 32 * j);
+        }
+        SHA256D64(out2, in, i);
+        BOOST_CHECK(memcmp(out1, out2, 32 * i) == 0);
+    }
+}
+
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/test/merkle_tests.cpp b/src/test/merkle_tests.cpp
index 56b897ffb7..367aed4651 100644
--- a/src/test/merkle_tests.cpp
+++ b/src/test/merkle_tests.cpp
@@ -9,6 +9,123 @@
 
 BOOST_FIXTURE_TEST_SUITE(merkle_tests, TestingSetup)
 
+static uint256 ComputeMerkleRootFromBranch(const uint256& leaf, const std::vector<uint256>& vMerkleBranch, uint32_t nIndex) {
+    uint256 hash = leaf;
+    for (std::vector<uint256>::const_iterator it = vMerkleBranch.begin(); it != vMerkleBranch.end(); ++it) {
+        if (nIndex & 1) {
+            hash = Hash(BEGIN(*it), END(*it), BEGIN(hash), END(hash));
+        } else {
+            hash = Hash(BEGIN(hash), END(hash), BEGIN(*it), END(*it));
+        }
+        nIndex >>= 1;
+    }
+    return hash;
+}
+
+/* This implements a constant-space merkle root/path calculator, limited to 2^32 leaves. */
+static void MerkleComputation(const std::vector<uint256>& leaves, uint256* proot, bool* pmutated, uint32_t branchpos, std::vector<uint256>* pbranch) {
+    if (pbranch) pbranch->clear();
+    if (leaves.size() == 0) {
+        if (pmutated) *pmutated = false;
+        if (proot) *proot = uint256();
+        return;
+    }
+    bool mutated = false;
+    // count is the number of leaves processed so far.
+    uint32_t count = 0;
+    // inner is an array of eagerly computed subtree hashes, indexed by tree
+    // level (0 being the leaves).
+    // For example, when count is 25 (11001 in binary), inner[4] is the hash of
+    // the first 16 leaves, inner[3] of the next 8 leaves, and inner[0] equal to
+    // the last leaf. The other inner entries are undefined.
+    uint256 inner[32];
+    // Which position in inner is a hash that depends on the matching leaf.
+    int matchlevel = -1;
+    // First process all leaves into 'inner' values.
+    while (count < leaves.size()) {
+        uint256 h = leaves[count];
+        bool matchh = count == branchpos;
+        count++;
+        int level;
+        // For each of the lower bits in count that are 0, do 1 step. Each
+        // corresponds to an inner value that existed before processing the
+        // current leaf, and each needs a hash to combine it.
+        for (level = 0; !(count & (((uint32_t)1) << level)); level++) {
+            if (pbranch) {
+                if (matchh) {
+                    pbranch->push_back(inner[level]);
+                } else if (matchlevel == level) {
+                    pbranch->push_back(h);
+                    matchh = true;
+                }
+            }
+            mutated |= (inner[level] == h);
+            CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
+        }
+        // Store the resulting hash at inner position level.
+        inner[level] = h;
+        if (matchh) {
+            matchlevel = level;
+        }
+    }
+    // Do a final 'sweep' over the rightmost branch of the tree to process
+    // odd levels, and reduce everything to a single top value.
+    // Level is the level (counted from the bottom) up to which we've sweeped.
+    int level = 0;
+    // As long as bit number level in count is zero, skip it. It means there
+    // is nothing left at this level.
+    while (!(count & (((uint32_t)1) << level))) {
+        level++;
+    }
+    uint256 h = inner[level];
+    bool matchh = matchlevel == level;
+    while (count != (((uint32_t)1) << level)) {
+        // If we reach this point, h is an inner value that is not the top.
+        // We combine it with itself (Bitcoin's special rule for odd levels in
+        // the tree) to produce a higher level one.
+        if (pbranch && matchh) {
+            pbranch->push_back(h);
+        }
+        CHash256().Write(h.begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
+        // Increment count to the value it would have if two entries at this
+        // level had existed.
+        count += (((uint32_t)1) << level);
+        level++;
+        // And propagate the result upwards accordingly.
+        while (!(count & (((uint32_t)1) << level))) {
+            if (pbranch) {
+                if (matchh) {
+                    pbranch->push_back(inner[level]);
+                } else if (matchlevel == level) {
+                    pbranch->push_back(h);
+                    matchh = true;
+                }
+            }
+            CHash256().Write(inner[level].begin(), 32).Write(h.begin(), 32).Finalize(h.begin());
+            level++;
+        }
+    }
+    // Return result.
+    if (pmutated) *pmutated = mutated;
+    if (proot) *proot = h;
+}
+
+static std::vector<uint256> ComputeMerkleBranch(const std::vector<uint256>& leaves, uint32_t position) {
+    std::vector<uint256> ret;
+    MerkleComputation(leaves, nullptr, nullptr, position, &ret);
+    return ret;
+}
+
+static std::vector<uint256> BlockMerkleBranch(const CBlock& block, uint32_t position)
+{
+    std::vector<uint256> leaves;
+    leaves.resize(block.vtx.size());
+    for (size_t s = 0; s < block.vtx.size(); s++) {
+        leaves[s] = block.vtx[s]->GetHash();
+    }
+    return ComputeMerkleBranch(leaves, position);
+}
+
 // Older version of the merkle root computation code, for comparison.
 static uint256 BlockBuildMerkleTree(const CBlock& block, bool* fMutated, std::vector<uint256>& vMerkleTree)
 {