uint256->arith_uint256 blob256->uint256

Introduce new opaque implementation of `uint256`, move old
"arithmetic" implementation to `arith_uint256.

7 files changed, 985 insertions, 701 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index d6ac6e1277..bc2b1aff96 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -74,11 +74,12 @@ BITCOIN_CORE_H = \
   alert.h \
   allocators.h \
   amount.h \
+  arith_uint256.h \
   base58.h \
   bloom.h \
   chain.h \
-  chainparams.h \
   chainparamsbase.h \
+  chainparams.h \
   chainparamsseeds.h \
   checkpoints.h \
   checkqueue.h \
@@ -87,8 +88,6 @@ BITCOIN_CORE_H = \
   coins.h \
   compat.h \
   compressor.h \
-  primitives/block.h \
-  primitives/transaction.h \
   core_io.h \
   crypter.h \
   db.h \
@@ -108,6 +107,8 @@ BITCOIN_CORE_H = \
   net.h \
   noui.h \
   pow.h \
+  primitives/block.h \
+  primitives/transaction.h \
   protocol.h \
   pubkey.h \
   random.h \
@@ -115,11 +116,11 @@ BITCOIN_CORE_H = \
   rpcprotocol.h \
   rpcserver.h \
   script/interpreter.h \
+  script/script_error.h \
   script/script.h \
   script/sigcache.h \
   script/sign.h \
   script/standard.h \
-  script/script_error.h \
   serialize.h \
   streams.h \
   sync.h \
@@ -132,13 +133,13 @@ BITCOIN_CORE_H = \
   uint256.h \
   undo.h \
   util.h \
-  utilstrencodings.h \
   utilmoneystr.h \
+  utilstrencodings.h \
   utiltime.h \
   version.h \
+  walletdb.h \
   wallet.h \
   wallet_ismine.h \
-  walletdb.h \
   compat/sanity.h
 
 JSON_H = \
@@ -261,18 +262,19 @@ libbitcoin_common_a_SOURCES = \
 # backward-compatibility objects and their sanity checks are linked.
 libbitcoin_util_a_CPPFLAGS = $(BITCOIN_INCLUDES)
 libbitcoin_util_a_SOURCES = \
-  compat/strnlen.cpp \
-  compat/glibc_sanity.cpp \
-  compat/glibcxx_sanity.cpp \
+  arith_uint256.cpp \
   chainparamsbase.cpp \
   clientversion.cpp \
+  compat/glibc_sanity.cpp \
+  compat/glibcxx_sanity.cpp \
+  compat/strnlen.cpp \
   random.cpp \
   rpcprotocol.cpp \
   sync.cpp \
   uint256.cpp \
   util.cpp \
-  utilstrencodings.cpp \
   utilmoneystr.cpp \
+  utilstrencodings.cpp \
   utiltime.cpp \
   $(BITCOIN_CORE_H)
 
@@ -352,19 +354,20 @@ bitcoin_cli_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 if BUILD_BITCOIN_LIBS
 include_HEADERS = script/bitcoinconsensus.h
 libbitcoinconsensus_la_SOURCES = \
-  primitives/transaction.cpp \
+  arith_uint256.cpp \
   crypto/hmac_sha512.cpp \
+  crypto/ripemd160.cpp \
   crypto/sha1.cpp \
   crypto/sha256.cpp \
   crypto/sha512.cpp \
-  crypto/ripemd160.cpp \
   eccryptoverify.cpp \
   ecwrapper.cpp \
   hash.cpp \
+  primitives/transaction.cpp \
   pubkey.cpp \
-  script/script.cpp \
-  script/interpreter.cpp \
   script/bitcoinconsensus.cpp \
+  script/interpreter.cpp \
+  script/script.cpp \
   uint256.cpp \
   utilstrencodings.cpp
 
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 5f388e2806..21d91acc6a 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -34,6 +34,7 @@ RAW_TEST_FILES = test/data/alertTests.raw
 GENERATED_TEST_FILES = $(JSON_TEST_FILES:.json=.json.h) $(RAW_TEST_FILES:.raw=.raw.h)
 
 BITCOIN_TESTS =\
+  test/arith_uint256_tests.cpp \
   test/bignum.h \
   test/alert_tests.cpp \
   test/allocator_tests.cpp \
@@ -67,7 +68,6 @@ BITCOIN_TESTS =\
   test/test_bitcoin.cpp \
   test/timedata_tests.cpp \
   test/transaction_tests.cpp \
-  test/uint256_tests.cpp \
   test/univalue_tests.cpp \
   test/util_tests.cpp
 
diff --git a/src/arith_uint256.cpp b/src/arith_uint256.cpp
new file mode 100644
index 0000000000..0dba429a8d
--- /dev/null
+++ b/src/arith_uint256.cpp
@@ -0,0 +1,357 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "arith_uint256.h"
+
+#include "utilstrencodings.h"
+
+#include <stdio.h>
+#include <string.h>
+
+template <unsigned int BITS>
+base_uint<BITS>::base_uint(const std::string& str)
+{
+    SetHex(str);
+}
+
+template <unsigned int BITS>
+base_uint<BITS>::base_uint(const std::vector<unsigned char>& vch)
+{
+    if (vch.size() != sizeof(pn))
+        throw uint_error("Converting vector of wrong size to base_uint");
+    memcpy(pn, &vch[0], sizeof(pn));
+}
+
+template <unsigned int BITS>
+base_uint<BITS>& base_uint<BITS>::operator<<=(unsigned int shift)
+{
+    base_uint<BITS> a(*this);
+    for (int i = 0; i < WIDTH; i++)
+        pn[i] = 0;
+    int k = shift / 32;
+    shift = shift % 32;
+    for (int i = 0; i < WIDTH; i++) {
+        if (i + k + 1 < WIDTH && shift != 0)
+            pn[i + k + 1] |= (a.pn[i] >> (32 - shift));
+        if (i + k < WIDTH)
+            pn[i + k] |= (a.pn[i] << shift);
+    }
+    return *this;
+}
+
+template <unsigned int BITS>
+base_uint<BITS>& base_uint<BITS>::operator>>=(unsigned int shift)
+{
+    base_uint<BITS> a(*this);
+    for (int i = 0; i < WIDTH; i++)
+        pn[i] = 0;
+    int k = shift / 32;
+    shift = shift % 32;
+    for (int i = 0; i < WIDTH; i++) {
+        if (i - k - 1 >= 0 && shift != 0)
+            pn[i - k - 1] |= (a.pn[i] << (32 - shift));
+        if (i - k >= 0)
+            pn[i - k] |= (a.pn[i] >> shift);
+    }
+    return *this;
+}
+
+template <unsigned int BITS>
+base_uint<BITS>& base_uint<BITS>::operator*=(uint32_t b32)
+{
+    uint64_t carry = 0;
+    for (int i = 0; i < WIDTH; i++) {
+        uint64_t n = carry + (uint64_t)b32 * pn[i];
+        pn[i] = n & 0xffffffff;
+        carry = n >> 32;
+    }
+    return *this;
+}
+
+template <unsigned int BITS>
+base_uint<BITS>& base_uint<BITS>::operator*=(const base_uint& b)
+{
+    base_uint<BITS> a = *this;
+    *this = 0;
+    for (int j = 0; j < WIDTH; j++) {
+        uint64_t carry = 0;
+        for (int i = 0; i + j < WIDTH; i++) {
+            uint64_t n = carry + pn[i + j] + (uint64_t)a.pn[j] * b.pn[i];
+            pn[i + j] = n & 0xffffffff;
+            carry = n >> 32;
+        }
+    }
+    return *this;
+}
+
+template <unsigned int BITS>
+base_uint<BITS>& base_uint<BITS>::operator/=(const base_uint& b)
+{
+    base_uint<BITS> div = b;     // make a copy, so we can shift.
+    base_uint<BITS> num = *this; // make a copy, so we can subtract.
+    *this = 0;                   // the quotient.
+    int num_bits = num.bits();
+    int div_bits = div.bits();
+    if (div_bits == 0)
+        throw uint_error("Division by zero");
+    if (div_bits > num_bits) // the result is certainly 0.
+        return *this;
+    int shift = num_bits - div_bits;
+    div <<= shift; // shift so that div and num align.
+    while (shift >= 0) {
+        if (num >= div) {
+            num -= div;
+            pn[shift / 32] |= (1 << (shift & 31)); // set a bit of the result.
+        }
+        div >>= 1; // shift back.
+        shift--;
+    }
+    // num now contains the remainder of the division.
+    return *this;
+}
+
+template <unsigned int BITS>
+int base_uint<BITS>::CompareTo(const base_uint<BITS>& b) const
+{
+    for (int i = WIDTH - 1; i >= 0; i--) {
+        if (pn[i] < b.pn[i])
+            return -1;
+        if (pn[i] > b.pn[i])
+            return 1;
+    }
+    return 0;
+}
+
+template <unsigned int BITS>
+bool base_uint<BITS>::EqualTo(uint64_t b) const
+{
+    for (int i = WIDTH - 1; i >= 2; i--) {
+        if (pn[i])
+            return false;
+    }
+    if (pn[1] != (b >> 32))
+        return false;
+    if (pn[0] != (b & 0xfffffffful))
+        return false;
+    return true;
+}
+
+template <unsigned int BITS>
+double base_uint<BITS>::getdouble() const
+{
+    double ret = 0.0;
+    double fact = 1.0;
+    for (int i = 0; i < WIDTH; i++) {
+        ret += fact * pn[i];
+        fact *= 4294967296.0;
+    }
+    return ret;
+}
+
+template <unsigned int BITS>
+std::string base_uint<BITS>::GetHex() const
+{
+    char psz[sizeof(pn) * 2 + 1];
+    for (unsigned int i = 0; i < sizeof(pn); i++)
+        sprintf(psz + i * 2, "%02x", ((unsigned char*)pn)[sizeof(pn) - i - 1]);
+    return std::string(psz, psz + sizeof(pn) * 2);
+}
+
+template <unsigned int BITS>
+void base_uint<BITS>::SetHex(const char* psz)
+{
+    memset(pn, 0, sizeof(pn));
+
+    // skip leading spaces
+    while (isspace(*psz))
+        psz++;
+
+    // skip 0x
+    if (psz[0] == '0' && tolower(psz[1]) == 'x')
+        psz += 2;
+
+    // hex string to uint
+    const char* pbegin = psz;
+    while (::HexDigit(*psz) != -1)
+        psz++;
+    psz--;
+    unsigned char* p1 = (unsigned char*)pn;
+    unsigned char* pend = p1 + WIDTH * 4;
+    while (psz >= pbegin && p1 < pend) {
+        *p1 = ::HexDigit(*psz--);
+        if (psz >= pbegin) {
+            *p1 |= ((unsigned char)::HexDigit(*psz--) << 4);
+            p1++;
+        }
+    }
+}
+
+template <unsigned int BITS>
+void base_uint<BITS>::SetHex(const std::string& str)
+{
+    SetHex(str.c_str());
+}
+
+template <unsigned int BITS>
+std::string base_uint<BITS>::ToString() const
+{
+    return (GetHex());
+}
+
+template <unsigned int BITS>
+unsigned int base_uint<BITS>::bits() const
+{
+    for (int pos = WIDTH - 1; pos >= 0; pos--) {
+        if (pn[pos]) {
+            for (int bits = 31; bits > 0; bits--) {
+                if (pn[pos] & 1 << bits)
+                    return 32 * pos + bits + 1;
+            }
+            return 32 * pos + 1;
+        }
+    }
+    return 0;
+}
+
+// Explicit instantiations for base_uint<160>
+template base_uint<160>::base_uint(const std::string&);
+template base_uint<160>::base_uint(const std::vector<unsigned char>&);
+template base_uint<160>& base_uint<160>::operator<<=(unsigned int);
+template base_uint<160>& base_uint<160>::operator>>=(unsigned int);
+template base_uint<160>& base_uint<160>::operator*=(uint32_t b32);
+template base_uint<160>& base_uint<160>::operator*=(const base_uint<160>& b);
+template base_uint<160>& base_uint<160>::operator/=(const base_uint<160>& b);
+template int base_uint<160>::CompareTo(const base_uint<160>&) const;
+template bool base_uint<160>::EqualTo(uint64_t) const;
+template double base_uint<160>::getdouble() const;
+template std::string base_uint<160>::GetHex() const;
+template std::string base_uint<160>::ToString() const;
+template void base_uint<160>::SetHex(const char*);
+template void base_uint<160>::SetHex(const std::string&);
+template unsigned int base_uint<160>::bits() const;
+
+// Explicit instantiations for base_uint<256>
+template base_uint<256>::base_uint(const std::string&);
+template base_uint<256>::base_uint(const std::vector<unsigned char>&);
+template base_uint<256>& base_uint<256>::operator<<=(unsigned int);
+template base_uint<256>& base_uint<256>::operator>>=(unsigned int);
+template base_uint<256>& base_uint<256>::operator*=(uint32_t b32);
+template base_uint<256>& base_uint<256>::operator*=(const base_uint<256>& b);
+template base_uint<256>& base_uint<256>::operator/=(const base_uint<256>& b);
+template int base_uint<256>::CompareTo(const base_uint<256>&) const;
+template bool base_uint<256>::EqualTo(uint64_t) const;
+template double base_uint<256>::getdouble() const;
+template std::string base_uint<256>::GetHex() const;
+template std::string base_uint<256>::ToString() const;
+template void base_uint<256>::SetHex(const char*);
+template void base_uint<256>::SetHex(const std::string&);
+template unsigned int base_uint<256>::bits() const;
+
+// This implementation directly uses shifts instead of going
+// through an intermediate MPI representation.
+arith_uint256& arith_uint256::SetCompact(uint32_t nCompact, bool* pfNegative, bool* pfOverflow)
+{
+    int nSize = nCompact >> 24;
+    uint32_t nWord = nCompact & 0x007fffff;
+    if (nSize <= 3) {
+        nWord >>= 8 * (3 - nSize);
+        *this = nWord;
+    } else {
+        *this = nWord;
+        *this <<= 8 * (nSize - 3);
+    }
+    if (pfNegative)
+        *pfNegative = nWord != 0 && (nCompact & 0x00800000) != 0;
+    if (pfOverflow)
+        *pfOverflow = nWord != 0 && ((nSize > 34) ||
+                                     (nWord > 0xff && nSize > 33) ||
+                                     (nWord > 0xffff && nSize > 32));
+    return *this;
+}
+
+uint32_t arith_uint256::GetCompact(bool fNegative) const
+{
+    int nSize = (bits() + 7) / 8;
+    uint32_t nCompact = 0;
+    if (nSize <= 3) {
+        nCompact = GetLow64() << 8 * (3 - nSize);
+    } else {
+        arith_uint256 bn = *this >> 8 * (nSize - 3);
+        nCompact = bn.GetLow64();
+    }
+    // The 0x00800000 bit denotes the sign.
+    // Thus, if it is already set, divide the mantissa by 256 and increase the exponent.
+    if (nCompact & 0x00800000) {
+        nCompact >>= 8;
+        nSize++;
+    }
+    assert((nCompact & ~0x007fffff) == 0);
+    assert(nSize < 256);
+    nCompact |= nSize << 24;
+    nCompact |= (fNegative && (nCompact & 0x007fffff) ? 0x00800000 : 0);
+    return nCompact;
+}
+
+static void inline HashMix(uint32_t& a, uint32_t& b, uint32_t& c)
+{
+    // Taken from lookup3, by Bob Jenkins.
+    a -= c;
+    a ^= ((c << 4) | (c >> 28));
+    c += b;
+    b -= a;
+    b ^= ((a << 6) | (a >> 26));
+    a += c;
+    c -= b;
+    c ^= ((b << 8) | (b >> 24));
+    b += a;
+    a -= c;
+    a ^= ((c << 16) | (c >> 16));
+    c += b;
+    b -= a;
+    b ^= ((a << 19) | (a >> 13));
+    a += c;
+    c -= b;
+    c ^= ((b << 4) | (b >> 28));
+    b += a;
+}
+
+static void inline HashFinal(uint32_t& a, uint32_t& b, uint32_t& c)
+{
+    // Taken from lookup3, by Bob Jenkins.
+    c ^= b;
+    c -= ((b << 14) | (b >> 18));
+    a ^= c;
+    a -= ((c << 11) | (c >> 21));
+    b ^= a;
+    b -= ((a << 25) | (a >> 7));
+    c ^= b;
+    c -= ((b << 16) | (b >> 16));
+    a ^= c;
+    a -= ((c << 4) | (c >> 28));
+    b ^= a;
+    b -= ((a << 14) | (a >> 18));
+    c ^= b;
+    c -= ((b << 24) | (b >> 8));
+}
+
+uint64_t arith_uint256::GetHash(const arith_uint256& salt) const
+{
+    uint32_t a, b, c;
+    a = b = c = 0xdeadbeef + (WIDTH << 2);
+
+    a += pn[0] ^ salt.pn[0];
+    b += pn[1] ^ salt.pn[1];
+    c += pn[2] ^ salt.pn[2];
+    HashMix(a, b, c);
+    a += pn[3] ^ salt.pn[3];
+    b += pn[4] ^ salt.pn[4];
+    c += pn[5] ^ salt.pn[5];
+    HashMix(a, b, c);
+    a += pn[6] ^ salt.pn[6];
+    b += pn[7] ^ salt.pn[7];
+    HashFinal(a, b, c);
+
+    return ((((uint64_t)b) << 32) | c);
+}
diff --git a/src/arith_uint256.h b/src/arith_uint256.h
index 3bb384ca8a..9e32b124c2 100644
--- a/src/arith_uint256.h
+++ b/src/arith_uint256.h
@@ -1,19 +1,350 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
 #ifndef BITCOIN_ARITH_UINT256_H
 #define BITCOIN_ARITH_UINT256_H
 
-// Temporary for migration to opaque uint160/256
-#include "uint256.h"
+#include <assert.h>
+#include <cstring>
+#include <stdexcept>
+#include <stdint.h>
+#include <string>
+#include <vector>
 
-class arith_uint256 : public uint256 {
+class uint_error : public std::runtime_error {
 public:
-    arith_uint256() {}
-    arith_uint256(const base_uint<256>& b) : uint256(b) {}
-    arith_uint256(uint64_t b) : uint256(b) {}
-    explicit arith_uint256(const std::string& str) : uint256(str) {}
-    explicit arith_uint256(const std::vector<unsigned char>& vch) : uint256(vch) {}
+    explicit uint_error(const std::string& str) : std::runtime_error(str) {}
+};
+
+/** Template base class for unsigned big integers. */
+template<unsigned int BITS>
+class base_uint
+{
+protected:
+    enum { WIDTH=BITS/32 };
+    uint32_t pn[WIDTH];
+public:
+
+    base_uint()
+    {
+        for (int i = 0; i < WIDTH; i++)
+            pn[i] = 0;
+    }
+
+    base_uint(const base_uint& b)
+    {
+        for (int i = 0; i < WIDTH; i++)
+            pn[i] = b.pn[i];
+    }
+
+    base_uint& operator=(const base_uint& b)
+    {
+        for (int i = 0; i < WIDTH; i++)
+            pn[i] = b.pn[i];
+        return *this;
+    }
+
+    base_uint(uint64_t b)
+    {
+        pn[0] = (unsigned int)b;
+        pn[1] = (unsigned int)(b >> 32);
+        for (int i = 2; i < WIDTH; i++)
+            pn[i] = 0;
+    }
+
+    explicit base_uint(const std::string& str);
+    explicit base_uint(const std::vector<unsigned char>& vch);
+
+    bool operator!() const
+    {
+        for (int i = 0; i < WIDTH; i++)
+            if (pn[i] != 0)
+                return false;
+        return true;
+    }
+
+    const base_uint operator~() const
+    {
+        base_uint ret;
+        for (int i = 0; i < WIDTH; i++)
+            ret.pn[i] = ~pn[i];
+        return ret;
+    }
+
+    const base_uint operator-() const
+    {
+        base_uint ret;
+        for (int i = 0; i < WIDTH; i++)
+            ret.pn[i] = ~pn[i];
+        ret++;
+        return ret;
+    }
+
+    double getdouble() const;
+
+    base_uint& operator=(uint64_t b)
+    {
+        pn[0] = (unsigned int)b;
+        pn[1] = (unsigned int)(b >> 32);
+        for (int i = 2; i < WIDTH; i++)
+            pn[i] = 0;
+        return *this;
+    }
+
+    base_uint& operator^=(const base_uint& b)
+    {
+        for (int i = 0; i < WIDTH; i++)
+            pn[i] ^= b.pn[i];
+        return *this;
+    }
+
+    base_uint& operator&=(const base_uint& b)
+    {
+        for (int i = 0; i < WIDTH; i++)
+            pn[i] &= b.pn[i];
+        return *this;
+    }
+
+    base_uint& operator|=(const base_uint& b)
+    {
+        for (int i = 0; i < WIDTH; i++)
+            pn[i] |= b.pn[i];
+        return *this;
+    }
+
+    base_uint& operator^=(uint64_t b)
+    {
+        pn[0] ^= (unsigned int)b;
+        pn[1] ^= (unsigned int)(b >> 32);
+        return *this;
+    }
+
+    base_uint& operator|=(uint64_t b)
+    {
+        pn[0] |= (unsigned int)b;
+        pn[1] |= (unsigned int)(b >> 32);
+        return *this;
+    }
+
+    base_uint& operator<<=(unsigned int shift);
+    base_uint& operator>>=(unsigned int shift);
+
+    base_uint& operator+=(const base_uint& b)
+    {
+        uint64_t carry = 0;
+        for (int i = 0; i < WIDTH; i++)
+        {
+            uint64_t n = carry + pn[i] + b.pn[i];
+            pn[i] = n & 0xffffffff;
+            carry = n >> 32;
+        }
+        return *this;
+    }
+
+    base_uint& operator-=(const base_uint& b)
+    {
+        *this += -b;
+        return *this;
+    }
+
+    base_uint& operator+=(uint64_t b64)
+    {
+        base_uint b;
+        b = b64;
+        *this += b;
+        return *this;
+    }
+
+    base_uint& operator-=(uint64_t b64)
+    {
+        base_uint b;
+        b = b64;
+        *this += -b;
+        return *this;
+    }
+
+    base_uint& operator*=(uint32_t b32);
+    base_uint& operator*=(const base_uint& b);
+    base_uint& operator/=(const base_uint& b);
+
+    base_uint& operator++()
+    {
+        // prefix operator
+        int i = 0;
+        while (++pn[i] == 0 && i < WIDTH-1)
+            i++;
+        return *this;
+    }
+
+    const base_uint operator++(int)
+    {
+        // postfix operator
+        const base_uint ret = *this;
+        ++(*this);
+        return ret;
+    }
+
+    base_uint& operator--()
+    {
+        // prefix operator
+        int i = 0;
+        while (--pn[i] == (uint32_t)-1 && i < WIDTH-1)
+            i++;
+        return *this;
+    }
+
+    const base_uint operator--(int)
+    {
+        // postfix operator
+        const base_uint ret = *this;
+        --(*this);
+        return ret;
+    }
+
+    int CompareTo(const base_uint& b) const;
+    bool EqualTo(uint64_t b) const;
+
+    friend inline const base_uint operator+(const base_uint& a, const base_uint& b) { return base_uint(a) += b; }
+    friend inline const base_uint operator-(const base_uint& a, const base_uint& b) { return base_uint(a) -= b; }
+    friend inline const base_uint operator*(const base_uint& a, const base_uint& b) { return base_uint(a) *= b; }
+    friend inline const base_uint operator/(const base_uint& a, const base_uint& b) { return base_uint(a) /= b; }
+    friend inline const base_uint operator|(const base_uint& a, const base_uint& b) { return base_uint(a) |= b; }
+    friend inline const base_uint operator&(const base_uint& a, const base_uint& b) { return base_uint(a) &= b; }
+    friend inline const base_uint operator^(const base_uint& a, const base_uint& b) { return base_uint(a) ^= b; }
+    friend inline const base_uint operator>>(const base_uint& a, int shift) { return base_uint(a) >>= shift; }
+    friend inline const base_uint operator<<(const base_uint& a, int shift) { return base_uint(a) <<= shift; }
+    friend inline const base_uint operator*(const base_uint& a, uint32_t b) { return base_uint(a) *= b; }
+    friend inline bool operator==(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) == 0; }
+    friend inline bool operator!=(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) != 0; }
+    friend inline bool operator>(const base_uint& a, const base_uint& b) { return a.CompareTo(b) > 0; }
+    friend inline bool operator<(const base_uint& a, const base_uint& b) { return a.CompareTo(b) < 0; }
+    friend inline bool operator>=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) >= 0; }
+    friend inline bool operator<=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) <= 0; }
+    friend inline bool operator==(const base_uint& a, uint64_t b) { return a.EqualTo(b); }
+    friend inline bool operator!=(const base_uint& a, uint64_t b) { return !a.EqualTo(b); }
+
+    std::string GetHex() const;
+    void SetHex(const char* psz);
+    void SetHex(const std::string& str);
+    std::string ToString() const;
+
+    unsigned char* begin()
+    {
+        return (unsigned char*)&pn[0];
+    }
+
+    unsigned char* end()
+    {
+        return (unsigned char*)&pn[WIDTH];
+    }
+
+    const unsigned char* begin() const
+    {
+        return (unsigned char*)&pn[0];
+    }
+
+    const unsigned char* end() const
+    {
+        return (unsigned char*)&pn[WIDTH];
+    }
+
+    unsigned int size() const
+    {
+        return sizeof(pn);
+    }
+
+    /**
+     * Returns the position of the highest bit set plus one, or zero if the
+     * value is zero.
+     */
+    unsigned int bits() const;
+
+    uint64_t GetLow64() const
+    {
+        assert(WIDTH >= 2);
+        return pn[0] | (uint64_t)pn[1] << 32;
+    }
+
+    unsigned int GetSerializeSize(int nType, int nVersion) const
+    {
+        return sizeof(pn);
+    }
+
+    template<typename Stream>
+    void Serialize(Stream& s, int nType, int nVersion) const
+    {
+        s.write((char*)pn, sizeof(pn));
+    }
+
+    template<typename Stream>
+    void Unserialize(Stream& s, int nType, int nVersion)
+    {
+        s.read((char*)pn, sizeof(pn));
+    }
+
+    // Temporary for migration to blob160/256
+    uint64_t GetCheapHash() const
+    {
+        return GetLow64();
+    }
+    void SetNull()
+    {
+        memset(pn, 0, sizeof(pn));
+    }
+    bool IsNull() const
+    {
+        for (int i = 0; i < WIDTH; i++)
+            if (pn[i] != 0)
+                return false;
+        return true;
+    }
 };
 
-#define ArithToUint256(x) (x)
-#define UintToArith256(x) (x)
+/** 160-bit unsigned big integer. */
+class arith_uint160 : public base_uint<160> {
+public:
+    arith_uint160() {}
+    arith_uint160(const base_uint<160>& b) : base_uint<160>(b) {}
+    arith_uint160(uint64_t b) : base_uint<160>(b) {}
+    explicit arith_uint160(const std::string& str) : base_uint<160>(str) {}
+    explicit arith_uint160(const std::vector<unsigned char>& vch) : base_uint<160>(vch) {}
+};
+
+/** 256-bit unsigned big integer. */
+class arith_uint256 : public base_uint<256> {
+public:
+    arith_uint256() {}
+    arith_uint256(const base_uint<256>& b) : base_uint<256>(b) {}
+    arith_uint256(uint64_t b) : base_uint<256>(b) {}
+    explicit arith_uint256(const std::string& str) : base_uint<256>(str) {}
+    explicit arith_uint256(const std::vector<unsigned char>& vch) : base_uint<256>(vch) {}
+
+    /**
+     * The "compact" format is a representation of a whole
+     * number N using an unsigned 32bit number similar to a
+     * floating point format.
+     * The most significant 8 bits are the unsigned exponent of base 256.
+     * This exponent can be thought of as "number of bytes of N".
+     * The lower 23 bits are the mantissa.
+     * Bit number 24 (0x800000) represents the sign of N.
+     * N = (-1^sign) * mantissa * 256^(exponent-3)
+     *
+     * Satoshi's original implementation used BN_bn2mpi() and BN_mpi2bn().
+     * MPI uses the most significant bit of the first byte as sign.
+     * Thus 0x1234560000 is compact (0x05123456)
+     * and  0xc0de000000 is compact (0x0600c0de)
+     *
+     * Bitcoin only uses this "compact" format for encoding difficulty
+     * targets, which are unsigned 256bit quantities.  Thus, all the
+     * complexities of the sign bit and using base 256 are probably an
+     * implementation accident.
+     */
+    arith_uint256& SetCompact(uint32_t nCompact, bool *pfNegative = NULL, bool *pfOverflow = NULL);
+    uint32_t GetCompact(bool fNegative = false) const;
+
+    uint64_t GetHash(const arith_uint256& salt) const;
+};
 
 #endif // BITCOIN_UINT256_H
diff --git a/src/test/uint256_tests.cpp b/src/test/arith_uint256_tests.cpp
index d05b28956c..f5f71da614 100644
--- a/src/test/uint256_tests.cpp
+++ b/src/test/arith_uint256_tests.cpp
@@ -8,65 +8,65 @@
 #include <iomanip>
 #include <limits>
 #include <cmath>
-#include "uint256.h"
+#include "arith_uint256.h"
 #include <string>
 #include "version.h"
 
-BOOST_AUTO_TEST_SUITE(uint256_tests)
- 
-const unsigned char R1Array[] = 
+BOOST_AUTO_TEST_SUITE(arith_uint256_tests)
+
+const unsigned char R1Array[] =
     "\x9c\x52\x4a\xdb\xcf\x56\x11\x12\x2b\x29\x12\x5e\x5d\x35\xd2\xd2"
     "\x22\x81\xaa\xb5\x33\xf0\x08\x32\xd5\x56\xb1\xf9\xea\xe5\x1d\x7d";
 const char R1ArrayHex[] = "7D1DE5EAF9B156D53208F033B5AA8122D2d2355d5e12292b121156cfdb4a529c";
 const double R1Ldouble = 0.4887374590559308955; // R1L equals roughly R1Ldouble * 2^256
-const double R1Sdouble = 0.7096329412477836074; 
-const uint256 R1L = uint256(std::vector<unsigned char>(R1Array,R1Array+32));
-const uint160 R1S = uint160(std::vector<unsigned char>(R1Array,R1Array+20));
+const double R1Sdouble = 0.7096329412477836074;
+const arith_uint256 R1L = arith_uint256(std::vector<unsigned char>(R1Array,R1Array+32));
+const arith_uint160 R1S = arith_uint160(std::vector<unsigned char>(R1Array,R1Array+20));
 const uint64_t R1LLow64 = 0x121156cfdb4a529cULL;
 
-const unsigned char R2Array[] = 
+const unsigned char R2Array[] =
     "\x70\x32\x1d\x7c\x47\xa5\x6b\x40\x26\x7e\x0a\xc3\xa6\x9c\xb6\xbf"
     "\x13\x30\x47\xa3\x19\x2d\xda\x71\x49\x13\x72\xf0\xb4\xca\x81\xd7";
-const uint256 R2L = uint256(std::vector<unsigned char>(R2Array,R2Array+32));
-const uint160 R2S = uint160(std::vector<unsigned char>(R2Array,R2Array+20));
+const arith_uint256 R2L = arith_uint256(std::vector<unsigned char>(R2Array,R2Array+32));
+const arith_uint160 R2S = arith_uint160(std::vector<unsigned char>(R2Array,R2Array+20));
 
 const char R1LplusR2L[] = "549FB09FEA236A1EA3E31D4D58F1B1369288D204211CA751527CFC175767850C";
 
-const unsigned char ZeroArray[] = 
+const unsigned char ZeroArray[] =
     "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
     "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
-const uint256 ZeroL = uint256(std::vector<unsigned char>(ZeroArray,ZeroArray+32));
-const uint160 ZeroS = uint160(std::vector<unsigned char>(ZeroArray,ZeroArray+20));
-                             
-const unsigned char OneArray[] = 
+const arith_uint256 ZeroL = arith_uint256(std::vector<unsigned char>(ZeroArray,ZeroArray+32));
+const arith_uint160 ZeroS = arith_uint160(std::vector<unsigned char>(ZeroArray,ZeroArray+20));
+
+const unsigned char OneArray[] =
     "\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
     "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
-const uint256 OneL = uint256(std::vector<unsigned char>(OneArray,OneArray+32));
-const uint160 OneS = uint160(std::vector<unsigned char>(OneArray,OneArray+20));
+const arith_uint256 OneL = arith_uint256(std::vector<unsigned char>(OneArray,OneArray+32));
+const arith_uint160 OneS = arith_uint160(std::vector<unsigned char>(OneArray,OneArray+20));
 
-const unsigned char MaxArray[] = 
+const unsigned char MaxArray[] =
     "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
     "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff";
-const uint256 MaxL = uint256(std::vector<unsigned char>(MaxArray,MaxArray+32));
-const uint160 MaxS = uint160(std::vector<unsigned char>(MaxArray,MaxArray+20));
+const arith_uint256 MaxL = arith_uint256(std::vector<unsigned char>(MaxArray,MaxArray+32));
+const arith_uint160 MaxS = arith_uint160(std::vector<unsigned char>(MaxArray,MaxArray+20));
 
-const uint256 HalfL = (OneL << 255);
-const uint160 HalfS = (OneS << 159);
+const arith_uint256 HalfL = (OneL << 255);
+const arith_uint160 HalfS = (OneS << 159);
 std::string ArrayToString(const unsigned char A[], unsigned int width)
 {
     std::stringstream Stream;
     Stream << std::hex;
-    for (unsigned int i = 0; i < width; ++i) 
+    for (unsigned int i = 0; i < width; ++i)
     {
         Stream<<std::setw(2)<<std::setfill('0')<<(unsigned int)A[width-i-1];
-    }       
+    }
     return Stream.str();
 }
 
 BOOST_AUTO_TEST_CASE( basics ) // constructors, equality, inequality
 {
     BOOST_CHECK(1 == 0+1);
-    // constructor uint256(vector<char>):
+    // constructor arith_uint256(vector<char>):
     BOOST_CHECK(R1L.ToString() == ArrayToString(R1Array,32));
     BOOST_CHECK(R1S.ToString() == ArrayToString(R1Array,20));
     BOOST_CHECK(R2L.ToString() == ArrayToString(R2Array,32));
@@ -88,104 +88,104 @@ BOOST_AUTO_TEST_CASE( basics ) // constructors, equality, inequality
     BOOST_CHECK(~MaxL == ZeroL && ~MaxS == ZeroS);
     BOOST_CHECK( ((R1L ^ R2L) ^ R1L) == R2L);
     BOOST_CHECK( ((R1S ^ R2S) ^ R1S) == R2S);
-    
+
     uint64_t Tmp64 = 0xc4dab720d9c7acaaULL;
-    for (unsigned int i = 0; i < 256; ++i) 
+    for (unsigned int i = 0; i < 256; ++i)
     {
-        BOOST_CHECK(ZeroL != (OneL << i)); 
-        BOOST_CHECK((OneL << i) != ZeroL); 
+        BOOST_CHECK(ZeroL != (OneL << i));
+        BOOST_CHECK((OneL << i) != ZeroL);
         BOOST_CHECK(R1L != (R1L ^ (OneL << i)));
-        BOOST_CHECK(((uint256(Tmp64) ^ (OneL << i) ) != Tmp64 ));
+        BOOST_CHECK(((arith_uint256(Tmp64) ^ (OneL << i) ) != Tmp64 ));
     }
-    BOOST_CHECK(ZeroL == (OneL << 256)); 
+    BOOST_CHECK(ZeroL == (OneL << 256));
 
-    for (unsigned int i = 0; i < 160; ++i) 
+    for (unsigned int i = 0; i < 160; ++i)
     {
-        BOOST_CHECK(ZeroS != (OneS << i)); 
-        BOOST_CHECK((OneS << i) != ZeroS); 
+        BOOST_CHECK(ZeroS != (OneS << i));
+        BOOST_CHECK((OneS << i) != ZeroS);
         BOOST_CHECK(R1S != (R1S ^ (OneS << i)));
-        BOOST_CHECK(((uint160(Tmp64) ^ (OneS << i) ) != Tmp64 ));
+        BOOST_CHECK(((arith_uint160(Tmp64) ^ (OneS << i) ) != Tmp64 ));
     }
-    BOOST_CHECK(ZeroS == (OneS << 256)); 
+    BOOST_CHECK(ZeroS == (OneS << 256));
 
     // String Constructor and Copy Constructor
-    BOOST_CHECK(uint256("0x"+R1L.ToString()) == R1L);
-    BOOST_CHECK(uint256("0x"+R2L.ToString()) == R2L);
-    BOOST_CHECK(uint256("0x"+ZeroL.ToString()) == ZeroL);
-    BOOST_CHECK(uint256("0x"+OneL.ToString()) == OneL);
-    BOOST_CHECK(uint256("0x"+MaxL.ToString()) == MaxL);
-    BOOST_CHECK(uint256(R1L.ToString()) == R1L);
-    BOOST_CHECK(uint256("   0x"+R1L.ToString()+"   ") == R1L);
-    BOOST_CHECK(uint256("") == ZeroL);
-    BOOST_CHECK(R1L == uint256(R1ArrayHex));
-    BOOST_CHECK(uint256(R1L) == R1L);
-    BOOST_CHECK((uint256(R1L^R2L)^R2L) == R1L);
-    BOOST_CHECK(uint256(ZeroL) == ZeroL);
-    BOOST_CHECK(uint256(OneL) == OneL);
-
-    BOOST_CHECK(uint160("0x"+R1S.ToString()) == R1S);
-    BOOST_CHECK(uint160("0x"+R2S.ToString()) == R2S);
-    BOOST_CHECK(uint160("0x"+ZeroS.ToString()) == ZeroS);
-    BOOST_CHECK(uint160("0x"+OneS.ToString()) == OneS);
-    BOOST_CHECK(uint160("0x"+MaxS.ToString()) == MaxS);
-    BOOST_CHECK(uint160(R1S.ToString()) == R1S);
-    BOOST_CHECK(uint160("   0x"+R1S.ToString()+"   ") == R1S); 
-    BOOST_CHECK(uint160("") == ZeroS);
-    BOOST_CHECK(R1S == uint160(R1ArrayHex));
-
-    BOOST_CHECK(uint160(R1S) == R1S);
-    BOOST_CHECK((uint160(R1S^R2S)^R2S) == R1S);
-    BOOST_CHECK(uint160(ZeroS) == ZeroS);
-    BOOST_CHECK(uint160(OneS) == OneS);
+    BOOST_CHECK(arith_uint256("0x"+R1L.ToString()) == R1L);
+    BOOST_CHECK(arith_uint256("0x"+R2L.ToString()) == R2L);
+    BOOST_CHECK(arith_uint256("0x"+ZeroL.ToString()) == ZeroL);
+    BOOST_CHECK(arith_uint256("0x"+OneL.ToString()) == OneL);
+    BOOST_CHECK(arith_uint256("0x"+MaxL.ToString()) == MaxL);
+    BOOST_CHECK(arith_uint256(R1L.ToString()) == R1L);
+    BOOST_CHECK(arith_uint256("   0x"+R1L.ToString()+"   ") == R1L);
+    BOOST_CHECK(arith_uint256("") == ZeroL);
+    BOOST_CHECK(R1L == arith_uint256(R1ArrayHex));
+    BOOST_CHECK(arith_uint256(R1L) == R1L);
+    BOOST_CHECK((arith_uint256(R1L^R2L)^R2L) == R1L);
+    BOOST_CHECK(arith_uint256(ZeroL) == ZeroL);
+    BOOST_CHECK(arith_uint256(OneL) == OneL);
+
+    BOOST_CHECK(arith_uint160("0x"+R1S.ToString()) == R1S);
+    BOOST_CHECK(arith_uint160("0x"+R2S.ToString()) == R2S);
+    BOOST_CHECK(arith_uint160("0x"+ZeroS.ToString()) == ZeroS);
+    BOOST_CHECK(arith_uint160("0x"+OneS.ToString()) == OneS);
+    BOOST_CHECK(arith_uint160("0x"+MaxS.ToString()) == MaxS);
+    BOOST_CHECK(arith_uint160(R1S.ToString()) == R1S);
+    BOOST_CHECK(arith_uint160("   0x"+R1S.ToString()+"   ") == R1S);
+    BOOST_CHECK(arith_uint160("") == ZeroS);
+    BOOST_CHECK(R1S == arith_uint160(R1ArrayHex));
+
+    BOOST_CHECK(arith_uint160(R1S) == R1S);
+    BOOST_CHECK((arith_uint160(R1S^R2S)^R2S) == R1S);
+    BOOST_CHECK(arith_uint160(ZeroS) == ZeroS);
+    BOOST_CHECK(arith_uint160(OneS) == OneS);
 
     // uint64_t constructor
-    BOOST_CHECK( (R1L & uint256("0xffffffffffffffff")) == uint256(R1LLow64));
-    BOOST_CHECK(ZeroL == uint256(0));
-    BOOST_CHECK(OneL == uint256(1));
-    BOOST_CHECK(uint256("0xffffffffffffffff") = uint256(0xffffffffffffffffULL));
-    BOOST_CHECK( (R1S & uint160("0xffffffffffffffff")) == uint160(R1LLow64));
-    BOOST_CHECK(ZeroS == uint160(0));
-    BOOST_CHECK(OneS == uint160(1));
-    BOOST_CHECK(uint160("0xffffffffffffffff") = uint160(0xffffffffffffffffULL));
+    BOOST_CHECK( (R1L & arith_uint256("0xffffffffffffffff")) == arith_uint256(R1LLow64));
+    BOOST_CHECK(ZeroL == arith_uint256(0));
+    BOOST_CHECK(OneL == arith_uint256(1));
+    BOOST_CHECK(arith_uint256("0xffffffffffffffff") = arith_uint256(0xffffffffffffffffULL));
+    BOOST_CHECK( (R1S & arith_uint160("0xffffffffffffffff")) == arith_uint160(R1LLow64));
+    BOOST_CHECK(ZeroS == arith_uint160(0));
+    BOOST_CHECK(OneS == arith_uint160(1));
+    BOOST_CHECK(arith_uint160("0xffffffffffffffff") = arith_uint160(0xffffffffffffffffULL));
 
     // Assignment (from base_uint)
-    uint256 tmpL = ~ZeroL; BOOST_CHECK(tmpL == ~ZeroL);
+    arith_uint256 tmpL = ~ZeroL; BOOST_CHECK(tmpL == ~ZeroL);
     tmpL = ~OneL; BOOST_CHECK(tmpL == ~OneL);
     tmpL = ~R1L; BOOST_CHECK(tmpL == ~R1L);
     tmpL = ~R2L; BOOST_CHECK(tmpL == ~R2L);
     tmpL = ~MaxL; BOOST_CHECK(tmpL == ~MaxL);
-    uint160 tmpS = ~ZeroS; BOOST_CHECK(tmpS == ~ZeroS);
+    arith_uint160 tmpS = ~ZeroS; BOOST_CHECK(tmpS == ~ZeroS);
     tmpS = ~OneS; BOOST_CHECK(tmpS == ~OneS);
     tmpS = ~R1S; BOOST_CHECK(tmpS == ~R1S);
     tmpS = ~R2S; BOOST_CHECK(tmpS == ~R2S);
     tmpS = ~MaxS; BOOST_CHECK(tmpS == ~MaxS);
 
     // Wrong length must throw exception.
-    BOOST_CHECK_THROW(uint256(std::vector<unsigned char>(OneArray,OneArray+31)), uint_error);
-    BOOST_CHECK_THROW(uint256(std::vector<unsigned char>(OneArray,OneArray+20)), uint_error);
-    BOOST_CHECK_THROW(uint160(std::vector<unsigned char>(OneArray,OneArray+32)), uint_error);
-    BOOST_CHECK_THROW(uint160(std::vector<unsigned char>(OneArray,OneArray+19)), uint_error);
+    BOOST_CHECK_THROW(arith_uint256(std::vector<unsigned char>(OneArray,OneArray+31)), uint_error);
+    BOOST_CHECK_THROW(arith_uint256(std::vector<unsigned char>(OneArray,OneArray+20)), uint_error);
+    BOOST_CHECK_THROW(arith_uint160(std::vector<unsigned char>(OneArray,OneArray+32)), uint_error);
+    BOOST_CHECK_THROW(arith_uint160(std::vector<unsigned char>(OneArray,OneArray+19)), uint_error);
 }
 
-void shiftArrayRight(unsigned char* to, const unsigned char* from, unsigned int arrayLength, unsigned int bitsToShift) 
+void shiftArrayRight(unsigned char* to, const unsigned char* from, unsigned int arrayLength, unsigned int bitsToShift)
 {
-    for (unsigned int T=0; T < arrayLength; ++T) 
+    for (unsigned int T=0; T < arrayLength; ++T)
     {
         unsigned int F = (T+bitsToShift/8);
-        if (F < arrayLength) 
+        if (F < arrayLength)
             to[T]  = from[F] >> (bitsToShift%8);
         else
             to[T] = 0;
-        if (F + 1 < arrayLength) 
+        if (F + 1 < arrayLength)
             to[T] |= from[(F+1)] << (8-bitsToShift%8);
     }
 }
 
-void shiftArrayLeft(unsigned char* to, const unsigned char* from, unsigned int arrayLength, unsigned int bitsToShift) 
+void shiftArrayLeft(unsigned char* to, const unsigned char* from, unsigned int arrayLength, unsigned int bitsToShift)
 {
-    for (unsigned int T=0; T < arrayLength; ++T) 
+    for (unsigned int T=0; T < arrayLength; ++T)
     {
-        if (T >= bitsToShift/8) 
+        if (T >= bitsToShift/8)
         {
             unsigned int F = T-bitsToShift/8;
             to[T]  = from[F] << (bitsToShift%8);
@@ -200,39 +200,39 @@ void shiftArrayLeft(unsigned char* to, const unsigned char* from, unsigned int a
 
 BOOST_AUTO_TEST_CASE( shifts ) { // "<<"  ">>"  "<<="  ">>="
     unsigned char TmpArray[32];
-    uint256 TmpL;
+    arith_uint256 TmpL;
     for (unsigned int i = 0; i < 256; ++i)
     {
         shiftArrayLeft(TmpArray, OneArray, 32, i);
-        BOOST_CHECK(uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (OneL << i));
+        BOOST_CHECK(arith_uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (OneL << i));
         TmpL = OneL; TmpL <<= i;
         BOOST_CHECK(TmpL == (OneL << i));
         BOOST_CHECK((HalfL >> (255-i)) == (OneL << i));
         TmpL = HalfL; TmpL >>= (255-i);
         BOOST_CHECK(TmpL == (OneL << i));
-                    
+
         shiftArrayLeft(TmpArray, R1Array, 32, i);
-        BOOST_CHECK(uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (R1L << i));
+        BOOST_CHECK(arith_uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (R1L << i));
         TmpL = R1L; TmpL <<= i;
         BOOST_CHECK(TmpL == (R1L << i));
 
         shiftArrayRight(TmpArray, R1Array, 32, i);
-        BOOST_CHECK(uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (R1L >> i)); 
+        BOOST_CHECK(arith_uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (R1L >> i));
         TmpL = R1L; TmpL >>= i;
         BOOST_CHECK(TmpL == (R1L >> i));
 
         shiftArrayLeft(TmpArray, MaxArray, 32, i);
-        BOOST_CHECK(uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (MaxL << i));
+        BOOST_CHECK(arith_uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (MaxL << i));
         TmpL = MaxL; TmpL <<= i;
         BOOST_CHECK(TmpL == (MaxL << i));
 
         shiftArrayRight(TmpArray, MaxArray, 32, i);
-        BOOST_CHECK(uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (MaxL >> i));
+        BOOST_CHECK(arith_uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (MaxL >> i));
         TmpL = MaxL; TmpL >>= i;
         BOOST_CHECK(TmpL == (MaxL >> i));
     }
-    uint256 c1L = uint256(0x0123456789abcdefULL);
-    uint256 c2L = c1L << 128;
+    arith_uint256 c1L = arith_uint256(0x0123456789abcdefULL);
+    arith_uint256 c2L = c1L << 128;
     for (unsigned int i = 0; i < 128; ++i) {
         BOOST_CHECK((c1L << i) == (c2L >> (128-i)));
     }
@@ -240,39 +240,39 @@ BOOST_AUTO_TEST_CASE( shifts ) { // "<<"  ">>"  "<<="  ">>="
         BOOST_CHECK((c1L << i) == (c2L << (i-128)));
     }
 
-    uint160 TmpS;
+    arith_uint160 TmpS;
     for (unsigned int i = 0; i < 160; ++i)
     {
         shiftArrayLeft(TmpArray, OneArray, 20, i);
-        BOOST_CHECK(uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (OneS << i));
+        BOOST_CHECK(arith_uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (OneS << i));
         TmpS = OneS; TmpS <<= i;
         BOOST_CHECK(TmpS == (OneS << i));
         BOOST_CHECK((HalfS >> (159-i)) == (OneS << i));
         TmpS = HalfS; TmpS >>= (159-i);
         BOOST_CHECK(TmpS == (OneS << i));
-                    
+
         shiftArrayLeft(TmpArray, R1Array, 20, i);
-        BOOST_CHECK(uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (R1S << i));
+        BOOST_CHECK(arith_uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (R1S << i));
         TmpS = R1S; TmpS <<= i;
         BOOST_CHECK(TmpS == (R1S << i));
 
         shiftArrayRight(TmpArray, R1Array, 20, i);
-        BOOST_CHECK(uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (R1S >> i)); 
+        BOOST_CHECK(arith_uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (R1S >> i));
         TmpS = R1S; TmpS >>= i;
         BOOST_CHECK(TmpS == (R1S >> i));
 
         shiftArrayLeft(TmpArray, MaxArray, 20, i);
-        BOOST_CHECK(uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (MaxS << i));
+        BOOST_CHECK(arith_uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (MaxS << i));
         TmpS = MaxS; TmpS <<= i;
         BOOST_CHECK(TmpS == (MaxS << i));
 
         shiftArrayRight(TmpArray, MaxArray, 20, i);
-        BOOST_CHECK(uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (MaxS >> i));
+        BOOST_CHECK(arith_uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (MaxS >> i));
         TmpS = MaxS; TmpS >>= i;
         BOOST_CHECK(TmpS == (MaxS >> i));
     }
-    uint160 c1S = uint160(0x0123456789abcdefULL);
-    uint160 c2S = c1S << 80;
+    arith_uint160 c1S = arith_uint160(0x0123456789abcdefULL);
+    arith_uint160 c2S = c1S << 80;
     for (unsigned int i = 0; i < 80; ++i) {
         BOOST_CHECK((c1S << i) == (c2S >> (80-i)));
     }
@@ -285,47 +285,47 @@ BOOST_AUTO_TEST_CASE( unaryOperators ) // !    ~    -
 {
     BOOST_CHECK(!ZeroL);  BOOST_CHECK(!ZeroS);
     BOOST_CHECK(!(!OneL));BOOST_CHECK(!(!OneS));
-    for (unsigned int i = 0; i < 256; ++i) 
+    for (unsigned int i = 0; i < 256; ++i)
         BOOST_CHECK(!(!(OneL<<i)));
-    for (unsigned int i = 0; i < 160; ++i) 
+    for (unsigned int i = 0; i < 160; ++i)
         BOOST_CHECK(!(!(OneS<<i)));
     BOOST_CHECK(!(!R1L));BOOST_CHECK(!(!R1S));
-    BOOST_CHECK(!(!R2S));BOOST_CHECK(!(!R2S)); 
+    BOOST_CHECK(!(!R2S));BOOST_CHECK(!(!R2S));
     BOOST_CHECK(!(!MaxL));BOOST_CHECK(!(!MaxS));
 
     BOOST_CHECK(~ZeroL == MaxL); BOOST_CHECK(~ZeroS == MaxS);
 
     unsigned char TmpArray[32];
-    for (unsigned int i = 0; i < 32; ++i) { TmpArray[i] = ~R1Array[i]; } 
-    BOOST_CHECK(uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (~R1L));
-    BOOST_CHECK(uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (~R1S));
+    for (unsigned int i = 0; i < 32; ++i) { TmpArray[i] = ~R1Array[i]; }
+    BOOST_CHECK(arith_uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (~R1L));
+    BOOST_CHECK(arith_uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (~R1S));
 
     BOOST_CHECK(-ZeroL == ZeroL); BOOST_CHECK(-ZeroS == ZeroS);
     BOOST_CHECK(-R1L == (~R1L)+1);
     BOOST_CHECK(-R1S == (~R1S)+1);
-    for (unsigned int i = 0; i < 256; ++i) 
+    for (unsigned int i = 0; i < 256; ++i)
         BOOST_CHECK(-(OneL<<i) == (MaxL << i));
-    for (unsigned int i = 0; i < 160; ++i) 
+    for (unsigned int i = 0; i < 160; ++i)
         BOOST_CHECK(-(OneS<<i) == (MaxS << i));
 }
 
 
 // Check if doing _A_ _OP_ _B_ results in the same as applying _OP_ onto each
-// element of Aarray and Barray, and then converting the result into a uint256.
+// element of Aarray and Barray, and then converting the result into a arith_uint256.
 #define CHECKBITWISEOPERATOR(_A_,_B_,_OP_)                              \
     for (unsigned int i = 0; i < 32; ++i) { TmpArray[i] = _A_##Array[i] _OP_ _B_##Array[i]; } \
-    BOOST_CHECK(uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (_A_##L _OP_ _B_##L)); \
+    BOOST_CHECK(arith_uint256(std::vector<unsigned char>(TmpArray,TmpArray+32)) == (_A_##L _OP_ _B_##L)); \
     for (unsigned int i = 0; i < 20; ++i) { TmpArray[i] = _A_##Array[i] _OP_ _B_##Array[i]; } \
-    BOOST_CHECK(uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (_A_##S _OP_ _B_##S));
+    BOOST_CHECK(arith_uint160(std::vector<unsigned char>(TmpArray,TmpArray+20)) == (_A_##S _OP_ _B_##S));
 
 #define CHECKASSIGNMENTOPERATOR(_A_,_B_,_OP_)                           \
     TmpL = _A_##L; TmpL _OP_##= _B_##L; BOOST_CHECK(TmpL == (_A_##L _OP_ _B_##L)); \
     TmpS = _A_##S; TmpS _OP_##= _B_##S; BOOST_CHECK(TmpS == (_A_##S _OP_ _B_##S));
 
-BOOST_AUTO_TEST_CASE( bitwiseOperators ) 
+BOOST_AUTO_TEST_CASE( bitwiseOperators )
 {
     unsigned char TmpArray[32];
-    
+
     CHECKBITWISEOPERATOR(R1,R2,|)
     CHECKBITWISEOPERATOR(R1,R2,^)
     CHECKBITWISEOPERATOR(R1,R2,&)
@@ -342,8 +342,8 @@ BOOST_AUTO_TEST_CASE( bitwiseOperators )
     CHECKBITWISEOPERATOR(Max,R1,^)
     CHECKBITWISEOPERATOR(Max,R1,&)
 
-    uint256 TmpL;
-    uint160 TmpS;
+    arith_uint256 TmpL;
+    arith_uint160 TmpS;
     CHECKASSIGNMENTOPERATOR(R1,R2,|)
     CHECKASSIGNMENTOPERATOR(R1,R2,^)
     CHECKASSIGNMENTOPERATOR(R1,R2,&)
@@ -360,20 +360,20 @@ BOOST_AUTO_TEST_CASE( bitwiseOperators )
     CHECKASSIGNMENTOPERATOR(Max,R1,^)
     CHECKASSIGNMENTOPERATOR(Max,R1,&)
 
-    uint64_t Tmp64 = 0xe1db685c9a0b47a2ULL; 
-    TmpL = R1L; TmpL |= Tmp64;  BOOST_CHECK(TmpL == (R1L | uint256(Tmp64)));
-    TmpS = R1S; TmpS |= Tmp64;  BOOST_CHECK(TmpS == (R1S | uint160(Tmp64)));
+    uint64_t Tmp64 = 0xe1db685c9a0b47a2ULL;
+    TmpL = R1L; TmpL |= Tmp64;  BOOST_CHECK(TmpL == (R1L | arith_uint256(Tmp64)));
+    TmpS = R1S; TmpS |= Tmp64;  BOOST_CHECK(TmpS == (R1S | arith_uint160(Tmp64)));
     TmpL = R1L; TmpL |= 0; BOOST_CHECK(TmpL == R1L);
     TmpS = R1S; TmpS |= 0; BOOST_CHECK(TmpS == R1S);
     TmpL ^= 0; BOOST_CHECK(TmpL == R1L);
     TmpS ^= 0; BOOST_CHECK(TmpS == R1S);
-    TmpL ^= Tmp64;  BOOST_CHECK(TmpL == (R1L ^ uint256(Tmp64)));
-    TmpS ^= Tmp64;  BOOST_CHECK(TmpS == (R1S ^ uint160(Tmp64)));
+    TmpL ^= Tmp64;  BOOST_CHECK(TmpL == (R1L ^ arith_uint256(Tmp64)));
+    TmpS ^= Tmp64;  BOOST_CHECK(TmpS == (R1S ^ arith_uint160(Tmp64)));
 }
 
 BOOST_AUTO_TEST_CASE( comparison ) // <= >= < >
 {
-    uint256 TmpL;
+    arith_uint256 TmpL;
     for (unsigned int i = 0; i < 256; ++i) {
         TmpL= OneL<< i;
         BOOST_CHECK( TmpL >= ZeroL && TmpL > ZeroL && ZeroL < TmpL && ZeroL <= TmpL);
@@ -383,7 +383,7 @@ BOOST_AUTO_TEST_CASE( comparison ) // <= >= < >
         BOOST_CHECK( R1L <= TmpL ); BOOST_CHECK( (R1L == TmpL) != (R1L < TmpL)); BOOST_CHECK( (TmpL == R1L) || !( R1L >= TmpL));
         BOOST_CHECK(! (TmpL < R1L)); BOOST_CHECK(! (R1L > TmpL));
     }
-    uint160 TmpS;
+    arith_uint160 TmpS;
     for (unsigned int i = 0; i < 160; ++i) {
         TmpS= OneS<< i;
         BOOST_CHECK( TmpS >= ZeroS && TmpS > ZeroS && ZeroS < TmpS && ZeroS <= TmpS);
@@ -395,10 +395,10 @@ BOOST_AUTO_TEST_CASE( comparison ) // <= >= < >
     }
 }
 
-BOOST_AUTO_TEST_CASE( plusMinus ) 
+BOOST_AUTO_TEST_CASE( plusMinus )
 {
-    uint256 TmpL = 0;
-    BOOST_CHECK(R1L+R2L == uint256(R1LplusR2L));
+    arith_uint256 TmpL = 0;
+    BOOST_CHECK(R1L+R2L == arith_uint256(R1LplusR2L));
     TmpL += R1L;
     BOOST_CHECK(TmpL == R1L);
     TmpL += R2L;
@@ -412,13 +412,13 @@ BOOST_AUTO_TEST_CASE( plusMinus )
         BOOST_CHECK( TmpL == (HalfL >> (i-1)) );
         TmpL = (MaxL>>i); TmpL += 1;
         BOOST_CHECK( TmpL == (HalfL >> (i-1)) );
-        TmpL = (MaxL>>i); 
+        TmpL = (MaxL>>i);
         BOOST_CHECK( TmpL++ == (MaxL>>i) );
         BOOST_CHECK( TmpL == (HalfL >> (i-1)));
     }
-    BOOST_CHECK(uint256(0xbedc77e27940a7ULL) + 0xee8d836fce66fbULL == uint256(0xbedc77e27940a7ULL + 0xee8d836fce66fbULL));
-    TmpL = uint256(0xbedc77e27940a7ULL); TmpL += 0xee8d836fce66fbULL;
-    BOOST_CHECK(TmpL == uint256(0xbedc77e27940a7ULL+0xee8d836fce66fbULL));
+    BOOST_CHECK(arith_uint256(0xbedc77e27940a7ULL) + 0xee8d836fce66fbULL == arith_uint256(0xbedc77e27940a7ULL + 0xee8d836fce66fbULL));
+    TmpL = arith_uint256(0xbedc77e27940a7ULL); TmpL += 0xee8d836fce66fbULL;
+    BOOST_CHECK(TmpL == arith_uint256(0xbedc77e27940a7ULL+0xee8d836fce66fbULL));
     TmpL -= 0xee8d836fce66fbULL;  BOOST_CHECK(TmpL == 0xbedc77e27940a7ULL);
     TmpL = R1L;
     BOOST_CHECK(++TmpL == R1L+1);
@@ -439,8 +439,8 @@ BOOST_AUTO_TEST_CASE( plusMinus )
     BOOST_CHECK(--TmpL == R1L-1);
 
     // 160-bit; copy-pasted
-    uint160 TmpS = 0;
-    BOOST_CHECK(R1S+R2S == uint160(R1LplusR2L));
+    arith_uint160 TmpS = 0;
+    BOOST_CHECK(R1S+R2S == arith_uint160(R1LplusR2L));
     TmpS += R1S;
     BOOST_CHECK(TmpS == R1S);
     TmpS += R2S;
@@ -454,13 +454,13 @@ BOOST_AUTO_TEST_CASE( plusMinus )
         BOOST_CHECK( TmpS == (HalfS >> (i-1)) );
         TmpS = (MaxS>>i); TmpS += 1;
         BOOST_CHECK( TmpS == (HalfS >> (i-1)) );
-        TmpS = (MaxS>>i); 
+        TmpS = (MaxS>>i);
         BOOST_CHECK( TmpS++ == (MaxS>>i) );
         BOOST_CHECK( TmpS == (HalfS >> (i-1)));
     }
-    BOOST_CHECK(uint160(0xbedc77e27940a7ULL) + 0xee8d836fce66fbULL == uint160(0xbedc77e27940a7ULL + 0xee8d836fce66fbULL));
-    TmpS = uint160(0xbedc77e27940a7ULL); TmpS += 0xee8d836fce66fbULL;
-    BOOST_CHECK(TmpS == uint160(0xbedc77e27940a7ULL+0xee8d836fce66fbULL));
+    BOOST_CHECK(arith_uint160(0xbedc77e27940a7ULL) + 0xee8d836fce66fbULL == arith_uint160(0xbedc77e27940a7ULL + 0xee8d836fce66fbULL));
+    TmpS = arith_uint160(0xbedc77e27940a7ULL); TmpS += 0xee8d836fce66fbULL;
+    BOOST_CHECK(TmpS == arith_uint160(0xbedc77e27940a7ULL+0xee8d836fce66fbULL));
     TmpS -= 0xee8d836fce66fbULL;  BOOST_CHECK(TmpS == 0xbedc77e27940a7ULL);
     TmpS = R1S;
     BOOST_CHECK(++TmpS == R1S+1);
@@ -521,8 +521,8 @@ BOOST_AUTO_TEST_CASE( multiply )
 
 BOOST_AUTO_TEST_CASE( divide )
 {
-    uint256 D1L("AD7133AC1977FA2B7");
-    uint256 D2L("ECD751716");
+    arith_uint256 D1L("AD7133AC1977FA2B7");
+    arith_uint256 D2L("ECD751716");
     BOOST_CHECK((R1L / D1L).ToString() == "00000000000000000b8ac01106981635d9ed112290f8895545a7654dde28fb3a");
     BOOST_CHECK((R1L / D2L).ToString() == "000000000873ce8efec5b67150bad3aa8c5fcb70e947586153bf2cec7c37c57a");
     BOOST_CHECK(R1L / OneL == R1L);
@@ -536,8 +536,8 @@ BOOST_AUTO_TEST_CASE( divide )
     BOOST_CHECK(MaxL / R2L == 1);
     BOOST_CHECK_THROW(R2L / ZeroL, uint_error);
 
-    uint160 D1S("D3C5EDCDEA54EB92679F0A4B4");
-    uint160 D2S("13037");
+    arith_uint160 D1S("D3C5EDCDEA54EB92679F0A4B4");
+    arith_uint160 D2S("13037");
     BOOST_CHECK((R1S / D1S).ToString() == "0000000000000000000000000db9af3beade6c02");
     BOOST_CHECK((R1S / D2S).ToString() == "000098dfb6cc40ca592bf74366794f298ada205c");
     BOOST_CHECK(R1S / OneS == R1S);
@@ -553,7 +553,7 @@ BOOST_AUTO_TEST_CASE( divide )
 }
 
 
-bool almostEqual(double d1, double d2) 
+bool almostEqual(double d1, double d2)
 {
     return fabs(d1-d2) <= 4*fabs(d1)*std::numeric_limits<double>::epsilon();
 }
@@ -564,7 +564,7 @@ BOOST_AUTO_TEST_CASE( methods ) // GetHex SetHex begin() end() size() GetLow64 G
     BOOST_CHECK(R2L.GetHex() == R2L.ToString());
     BOOST_CHECK(OneL.GetHex() == OneL.ToString());
     BOOST_CHECK(MaxL.GetHex() == MaxL.ToString());
-    uint256 TmpL(R1L);
+    arith_uint256 TmpL(R1L);
     BOOST_CHECK(TmpL == R1L);
     TmpL.SetHex(R2L.ToString());   BOOST_CHECK(TmpL == R2L);
     TmpL.SetHex(ZeroL.ToString()); BOOST_CHECK(TmpL == 0);
@@ -612,7 +612,7 @@ BOOST_AUTO_TEST_CASE( methods ) // GetHex SetHex begin() end() size() GetLow64 G
     BOOST_CHECK(R2S.GetHex() == R2S.ToString());
     BOOST_CHECK(OneS.GetHex() == OneS.ToString());
     BOOST_CHECK(MaxS.GetHex() == MaxS.ToString());
-    uint160 TmpS(R1S);
+    arith_uint160 TmpS(R1S);
     BOOST_CHECK(TmpS == R1S);
     TmpS.SetHex(R2S.ToString());   BOOST_CHECK(TmpS == R2S);
     TmpS.SetHex(ZeroS.ToString()); BOOST_CHECK(TmpS == 0);
@@ -634,7 +634,7 @@ BOOST_AUTO_TEST_CASE( methods ) // GetHex SetHex begin() end() size() GetLow64 G
     BOOST_CHECK(MaxS.begin() + 20 == MaxS.end());
     BOOST_CHECK(TmpS.begin() + 20 == TmpS.end());
     BOOST_CHECK(R1S.GetLow64()  == R1LLow64);
-    BOOST_CHECK(HalfS.GetLow64() ==0x0000000000000000ULL); 
+    BOOST_CHECK(HalfS.GetLow64() ==0x0000000000000000ULL);
     BOOST_CHECK(OneS.GetLow64() ==0x0000000000000001ULL);
     BOOST_CHECK(R1S.GetSerializeSize(0,PROTOCOL_VERSION) == 20);
     BOOST_CHECK(ZeroS.GetSerializeSize(0,PROTOCOL_VERSION) == 20);
@@ -654,17 +654,17 @@ BOOST_AUTO_TEST_CASE( methods ) // GetHex SetHex begin() end() size() GetLow64 G
     TmpS.Unserialize(ss,0,PROTOCOL_VERSION);
     BOOST_CHECK(MaxS == TmpS);
     ss.str("");
-    
-    for (unsigned int i = 0; i < 255; ++i) 
+
+    for (unsigned int i = 0; i < 255; ++i)
     {
         BOOST_CHECK((OneL << i).getdouble() == ldexp(1.0,i));
         if (i < 160) BOOST_CHECK((OneS << i).getdouble() == ldexp(1.0,i));
     }
     BOOST_CHECK(ZeroL.getdouble() == 0.0);
     BOOST_CHECK(ZeroS.getdouble() == 0.0);
-    for (int i = 256; i > 53; --i) 
+    for (int i = 256; i > 53; --i)
         BOOST_CHECK(almostEqual((R1L>>(256-i)).getdouble(), ldexp(R1Ldouble,i)));
-    for (int i = 160; i > 53; --i) 
+    for (int i = 160; i > 53; --i)
         BOOST_CHECK(almostEqual((R1S>>(160-i)).getdouble(), ldexp(R1Sdouble,i)));
     uint64_t R1L64part = (R1L>>192).GetLow64();
     uint64_t R1S64part = (R1S>>96).GetLow64();
@@ -677,7 +677,7 @@ BOOST_AUTO_TEST_CASE( methods ) // GetHex SetHex begin() end() size() GetLow64 G
 
 BOOST_AUTO_TEST_CASE(bignum_SetCompact)
 {
-    uint256 num;
+    arith_uint256 num;
     bool fNegative;
     bool fOverflow;
     num.SetCompact(0, &fNegative, &fOverflow);
@@ -809,21 +809,21 @@ BOOST_AUTO_TEST_CASE( getmaxcoverage ) // some more tests just to get 100% cover
     // ~R1L give a base_uint<256>
     BOOST_CHECK((~~R1L >> 10) == (R1L >> 10)); BOOST_CHECK((~~R1S >> 10) == (R1S >> 10));
     BOOST_CHECK((~~R1L << 10) == (R1L << 10)); BOOST_CHECK((~~R1S << 10) == (R1S << 10));
-    BOOST_CHECK(!(~~R1L < R1L)); BOOST_CHECK(!(~~R1S < R1S)); 
-    BOOST_CHECK(~~R1L <= R1L); BOOST_CHECK(~~R1S <= R1S); 
-    BOOST_CHECK(!(~~R1L > R1L)); BOOST_CHECK(!(~~R1S > R1S)); 
-    BOOST_CHECK(~~R1L >= R1L); BOOST_CHECK(~~R1S >= R1S); 
-    BOOST_CHECK(!(R1L < ~~R1L)); BOOST_CHECK(!(R1S < ~~R1S)); 
-    BOOST_CHECK(R1L <= ~~R1L); BOOST_CHECK(R1S <= ~~R1S); 
-    BOOST_CHECK(!(R1L > ~~R1L)); BOOST_CHECK(!(R1S > ~~R1S)); 
-    BOOST_CHECK(R1L >= ~~R1L); BOOST_CHECK(R1S >= ~~R1S); 
-    
+    BOOST_CHECK(!(~~R1L < R1L)); BOOST_CHECK(!(~~R1S < R1S));
+    BOOST_CHECK(~~R1L <= R1L); BOOST_CHECK(~~R1S <= R1S);
+    BOOST_CHECK(!(~~R1L > R1L)); BOOST_CHECK(!(~~R1S > R1S));
+    BOOST_CHECK(~~R1L >= R1L); BOOST_CHECK(~~R1S >= R1S);
+    BOOST_CHECK(!(R1L < ~~R1L)); BOOST_CHECK(!(R1S < ~~R1S));
+    BOOST_CHECK(R1L <= ~~R1L); BOOST_CHECK(R1S <= ~~R1S);
+    BOOST_CHECK(!(R1L > ~~R1L)); BOOST_CHECK(!(R1S > ~~R1S));
+    BOOST_CHECK(R1L >= ~~R1L); BOOST_CHECK(R1S >= ~~R1S);
+
     BOOST_CHECK(~~R1L + R2L == R1L + ~~R2L);
     BOOST_CHECK(~~R1S + R2S == R1S + ~~R2S);
     BOOST_CHECK(~~R1L - R2L == R1L - ~~R2L);
     BOOST_CHECK(~~R1S - R2S == R1S - ~~R2S);
-    BOOST_CHECK(~R1L != R1L); BOOST_CHECK(R1L != ~R1L); 
-    BOOST_CHECK(~R1S != R1S); BOOST_CHECK(R1S != ~R1S); 
+    BOOST_CHECK(~R1L != R1L); BOOST_CHECK(R1L != ~R1L);
+    BOOST_CHECK(~R1S != R1S); BOOST_CHECK(R1S != ~R1S);
     unsigned char TmpArray[32];
     CHECKBITWISEOPERATOR(~R1,R2,|)
     CHECKBITWISEOPERATOR(~R1,R2,^)
@@ -834,4 +834,3 @@ BOOST_AUTO_TEST_CASE( getmaxcoverage ) // some more tests just to get 100% cover
 }
 
 BOOST_AUTO_TEST_SUITE_END()
-
diff --git a/src/uint256.cpp b/src/uint256.cpp
index 918c1a7cd7..3b1334a032 100644
--- a/src/uint256.cpp
+++ b/src/uint256.cpp
@@ -11,158 +11,25 @@
 #include <string.h>
 
 template <unsigned int BITS>
-base_uint<BITS>::base_uint(const std::string& str)
+base_blob<BITS>::base_blob(const std::vector<unsigned char>& vch)
 {
-    SetHex(str);
+    assert(vch.size() == sizeof(data));
+    memcpy(data, &vch[0], sizeof(data));
 }
 
 template <unsigned int BITS>
-base_uint<BITS>::base_uint(const std::vector<unsigned char>& vch)
+std::string base_blob<BITS>::GetHex() const
 {
-    if (vch.size() != sizeof(pn))
-        throw uint_error("Converting vector of wrong size to base_uint");
-    memcpy(pn, &vch[0], sizeof(pn));
+    char psz[sizeof(data) * 2 + 1];
+    for (unsigned int i = 0; i < sizeof(data); i++)
+        sprintf(psz + i * 2, "%02x", data[sizeof(data) - i - 1]);
+    return std::string(psz, psz + sizeof(data) * 2);
 }
 
 template <unsigned int BITS>
-base_uint<BITS>& base_uint<BITS>::operator<<=(unsigned int shift)
+void base_blob<BITS>::SetHex(const char* psz)
 {
-    base_uint<BITS> a(*this);
-    for (int i = 0; i < WIDTH; i++)
-        pn[i] = 0;
-    int k = shift / 32;
-    shift = shift % 32;
-    for (int i = 0; i < WIDTH; i++) {
-        if (i + k + 1 < WIDTH && shift != 0)
-            pn[i + k + 1] |= (a.pn[i] >> (32 - shift));
-        if (i + k < WIDTH)
-            pn[i + k] |= (a.pn[i] << shift);
-    }
-    return *this;
-}
-
-template <unsigned int BITS>
-base_uint<BITS>& base_uint<BITS>::operator>>=(unsigned int shift)
-{
-    base_uint<BITS> a(*this);
-    for (int i = 0; i < WIDTH; i++)
-        pn[i] = 0;
-    int k = shift / 32;
-    shift = shift % 32;
-    for (int i = 0; i < WIDTH; i++) {
-        if (i - k - 1 >= 0 && shift != 0)
-            pn[i - k - 1] |= (a.pn[i] << (32 - shift));
-        if (i - k >= 0)
-            pn[i - k] |= (a.pn[i] >> shift);
-    }
-    return *this;
-}
-
-template <unsigned int BITS>
-base_uint<BITS>& base_uint<BITS>::operator*=(uint32_t b32)
-{
-    uint64_t carry = 0;
-    for (int i = 0; i < WIDTH; i++) {
-        uint64_t n = carry + (uint64_t)b32 * pn[i];
-        pn[i] = n & 0xffffffff;
-        carry = n >> 32;
-    }
-    return *this;
-}
-
-template <unsigned int BITS>
-base_uint<BITS>& base_uint<BITS>::operator*=(const base_uint& b)
-{
-    base_uint<BITS> a = *this;
-    *this = 0;
-    for (int j = 0; j < WIDTH; j++) {
-        uint64_t carry = 0;
-        for (int i = 0; i + j < WIDTH; i++) {
-            uint64_t n = carry + pn[i + j] + (uint64_t)a.pn[j] * b.pn[i];
-            pn[i + j] = n & 0xffffffff;
-            carry = n >> 32;
-        }
-    }
-    return *this;
-}
-
-template <unsigned int BITS>
-base_uint<BITS>& base_uint<BITS>::operator/=(const base_uint& b)
-{
-    base_uint<BITS> div = b;     // make a copy, so we can shift.
-    base_uint<BITS> num = *this; // make a copy, so we can subtract.
-    *this = 0;                   // the quotient.
-    int num_bits = num.bits();
-    int div_bits = div.bits();
-    if (div_bits == 0)
-        throw uint_error("Division by zero");
-    if (div_bits > num_bits) // the result is certainly 0.
-        return *this;
-    int shift = num_bits - div_bits;
-    div <<= shift; // shift so that div and num align.
-    while (shift >= 0) {
-        if (num >= div) {
-            num -= div;
-            pn[shift / 32] |= (1 << (shift & 31)); // set a bit of the result.
-        }
-        div >>= 1; // shift back.
-        shift--;
-    }
-    // num now contains the remainder of the division.
-    return *this;
-}
-
-template <unsigned int BITS>
-int base_uint<BITS>::CompareTo(const base_uint<BITS>& b) const
-{
-    for (int i = WIDTH - 1; i >= 0; i--) {
-        if (pn[i] < b.pn[i])
-            return -1;
-        if (pn[i] > b.pn[i])
-            return 1;
-    }
-    return 0;
-}
-
-template <unsigned int BITS>
-bool base_uint<BITS>::EqualTo(uint64_t b) const
-{
-    for (int i = WIDTH - 1; i >= 2; i--) {
-        if (pn[i])
-            return false;
-    }
-    if (pn[1] != (b >> 32))
-        return false;
-    if (pn[0] != (b & 0xfffffffful))
-        return false;
-    return true;
-}
-
-template <unsigned int BITS>
-double base_uint<BITS>::getdouble() const
-{
-    double ret = 0.0;
-    double fact = 1.0;
-    for (int i = 0; i < WIDTH; i++) {
-        ret += fact * pn[i];
-        fact *= 4294967296.0;
-    }
-    return ret;
-}
-
-template <unsigned int BITS>
-std::string base_uint<BITS>::GetHex() const
-{
-    char psz[sizeof(pn) * 2 + 1];
-    for (unsigned int i = 0; i < sizeof(pn); i++)
-        sprintf(psz + i * 2, "%02x", ((unsigned char*)pn)[sizeof(pn) - i - 1]);
-    return std::string(psz, psz + sizeof(pn) * 2);
-}
-
-template <unsigned int BITS>
-void base_uint<BITS>::SetHex(const char* psz)
-{
-    memset(pn, 0, sizeof(pn));
+    memset(data, 0, sizeof(data));
 
     // skip leading spaces
     while (isspace(*psz))
@@ -177,7 +44,7 @@ void base_uint<BITS>::SetHex(const char* psz)
     while (::HexDigit(*psz) != -1)
         psz++;
     psz--;
-    unsigned char* p1 = (unsigned char*)pn;
+    unsigned char* p1 = (unsigned char*)data;
     unsigned char* pend = p1 + WIDTH * 4;
     while (psz >= pbegin && p1 < pend) {
         *p1 = ::HexDigit(*psz--);
@@ -189,110 +56,30 @@ void base_uint<BITS>::SetHex(const char* psz)
 }
 
 template <unsigned int BITS>
-void base_uint<BITS>::SetHex(const std::string& str)
+void base_blob<BITS>::SetHex(const std::string& str)
 {
     SetHex(str.c_str());
 }
 
 template <unsigned int BITS>
-std::string base_uint<BITS>::ToString() const
+std::string base_blob<BITS>::ToString() const
 {
     return (GetHex());
 }
 
-template <unsigned int BITS>
-unsigned int base_uint<BITS>::bits() const
-{
-    for (int pos = WIDTH - 1; pos >= 0; pos--) {
-        if (pn[pos]) {
-            for (int bits = 31; bits > 0; bits--) {
-                if (pn[pos] & 1 << bits)
-                    return 32 * pos + bits + 1;
-            }
-            return 32 * pos + 1;
-        }
-    }
-    return 0;
-}
-
-// Explicit instantiations for base_uint<160>
-template base_uint<160>::base_uint(const std::string&);
-template base_uint<160>::base_uint(const std::vector<unsigned char>&);
-template base_uint<160>& base_uint<160>::operator<<=(unsigned int);
-template base_uint<160>& base_uint<160>::operator>>=(unsigned int);
-template base_uint<160>& base_uint<160>::operator*=(uint32_t b32);
-template base_uint<160>& base_uint<160>::operator*=(const base_uint<160>& b);
-template base_uint<160>& base_uint<160>::operator/=(const base_uint<160>& b);
-template int base_uint<160>::CompareTo(const base_uint<160>&) const;
-template bool base_uint<160>::EqualTo(uint64_t) const;
-template double base_uint<160>::getdouble() const;
-template std::string base_uint<160>::GetHex() const;
-template std::string base_uint<160>::ToString() const;
-template void base_uint<160>::SetHex(const char*);
-template void base_uint<160>::SetHex(const std::string&);
-template unsigned int base_uint<160>::bits() const;
+// Explicit instantiations for base_blob<160>
+template base_blob<160>::base_blob(const std::vector<unsigned char>&);
+template std::string base_blob<160>::GetHex() const;
+template std::string base_blob<160>::ToString() const;
+template void base_blob<160>::SetHex(const char*);
+template void base_blob<160>::SetHex(const std::string&);
 
-// Explicit instantiations for base_uint<256>
-template base_uint<256>::base_uint(const std::string&);
-template base_uint<256>::base_uint(const std::vector<unsigned char>&);
-template base_uint<256>& base_uint<256>::operator<<=(unsigned int);
-template base_uint<256>& base_uint<256>::operator>>=(unsigned int);
-template base_uint<256>& base_uint<256>::operator*=(uint32_t b32);
-template base_uint<256>& base_uint<256>::operator*=(const base_uint<256>& b);
-template base_uint<256>& base_uint<256>::operator/=(const base_uint<256>& b);
-template int base_uint<256>::CompareTo(const base_uint<256>&) const;
-template bool base_uint<256>::EqualTo(uint64_t) const;
-template double base_uint<256>::getdouble() const;
-template std::string base_uint<256>::GetHex() const;
-template std::string base_uint<256>::ToString() const;
-template void base_uint<256>::SetHex(const char*);
-template void base_uint<256>::SetHex(const std::string&);
-template unsigned int base_uint<256>::bits() const;
-
-// This implementation directly uses shifts instead of going
-// through an intermediate MPI representation.
-uint256& uint256::SetCompact(uint32_t nCompact, bool* pfNegative, bool* pfOverflow)
-{
-    int nSize = nCompact >> 24;
-    uint32_t nWord = nCompact & 0x007fffff;
-    if (nSize <= 3) {
-        nWord >>= 8 * (3 - nSize);
-        *this = nWord;
-    } else {
-        *this = nWord;
-        *this <<= 8 * (nSize - 3);
-    }
-    if (pfNegative)
-        *pfNegative = nWord != 0 && (nCompact & 0x00800000) != 0;
-    if (pfOverflow)
-        *pfOverflow = nWord != 0 && ((nSize > 34) ||
-                                     (nWord > 0xff && nSize > 33) ||
-                                     (nWord > 0xffff && nSize > 32));
-    return *this;
-}
-
-uint32_t uint256::GetCompact(bool fNegative) const
-{
-    int nSize = (bits() + 7) / 8;
-    uint32_t nCompact = 0;
-    if (nSize <= 3) {
-        nCompact = GetLow64() << 8 * (3 - nSize);
-    } else {
-        uint256 bn = *this >> 8 * (nSize - 3);
-        nCompact = bn.GetLow64();
-    }
-    // The 0x00800000 bit denotes the sign.
-    // Thus, if it is already set, divide the mantissa by 256 and increase the exponent.
-    if (nCompact & 0x00800000) {
-        nCompact >>= 8;
-        nSize++;
-    }
-    assert((nCompact & ~0x007fffff) == 0);
-    assert(nSize < 256);
-    nCompact |= nSize << 24;
-    nCompact |= (fNegative && (nCompact & 0x007fffff) ? 0x00800000 : 0);
-    return nCompact;
-}
+// Explicit instantiations for base_blob<256>
+template base_blob<256>::base_blob(const std::vector<unsigned char>&);
+template std::string base_blob<256>::GetHex() const;
+template std::string base_blob<256>::ToString() const;
+template void base_blob<256>::SetHex(const char*);
+template void base_blob<256>::SetHex(const std::string&);
 
 static void inline HashMix(uint32_t& a, uint32_t& b, uint32_t& c)
 {
@@ -339,18 +126,20 @@ static void inline HashFinal(uint32_t& a, uint32_t& b, uint32_t& c)
 uint64_t uint256::GetHash(const uint256& salt) const
 {
     uint32_t a, b, c;
+    const uint32_t *pn = (const uint32_t*)data;
+    const uint32_t *salt_pn = (const uint32_t*)salt.data;
     a = b = c = 0xdeadbeef + (WIDTH << 2);
 
-    a += pn[0] ^ salt.pn[0];
-    b += pn[1] ^ salt.pn[1];
-    c += pn[2] ^ salt.pn[2];
+    a += pn[0] ^ salt_pn[0];
+    b += pn[1] ^ salt_pn[1];
+    c += pn[2] ^ salt_pn[2];
     HashMix(a, b, c);
-    a += pn[3] ^ salt.pn[3];
-    b += pn[4] ^ salt.pn[4];
-    c += pn[5] ^ salt.pn[5];
+    a += pn[3] ^ salt_pn[3];
+    b += pn[4] ^ salt_pn[4];
+    c += pn[5] ^ salt_pn[5];
     HashMix(a, b, c);
-    a += pn[6] ^ salt.pn[6];
-    b += pn[7] ^ salt.pn[7];
+    a += pn[6] ^ salt_pn[6];
+    b += pn[7] ^ salt_pn[7];
     HashFinal(a, b, c);
 
     return ((((uint64_t)b) << 32) | c);
diff --git a/src/uint256.h b/src/uint256.h
index 8189b27cb3..6d016ab164 100644
--- a/src/uint256.h
+++ b/src/uint256.h
@@ -13,217 +13,37 @@
 #include <string>
 #include <vector>
 
-class uint_error : public std::runtime_error {
-public:
-    explicit uint_error(const std::string& str) : std::runtime_error(str) {}
-};
-
-/** Template base class for unsigned big integers. */
+/** Template base class for fixed-sized opaque blobs. */
 template<unsigned int BITS>
-class base_uint
+class base_blob
 {
 protected:
-    enum { WIDTH=BITS/32 };
-    uint32_t pn[WIDTH];
+    enum { WIDTH=BITS/8 };
+    uint8_t data[WIDTH];
 public:
-
-    base_uint()
+    base_blob()
     {
-        for (int i = 0; i < WIDTH; i++)
-            pn[i] = 0;
+        memset(data, 0, sizeof(data));
     }
 
-    base_uint(const base_uint& b)
-    {
-        for (int i = 0; i < WIDTH; i++)
-            pn[i] = b.pn[i];
-    }
-
-    base_uint& operator=(const base_uint& b)
-    {
-        for (int i = 0; i < WIDTH; i++)
-            pn[i] = b.pn[i];
-        return *this;
-    }
+    explicit base_blob(const std::vector<unsigned char>& vch);
 
-    base_uint(uint64_t b)
-    {
-        pn[0] = (unsigned int)b;
-        pn[1] = (unsigned int)(b >> 32);
-        for (int i = 2; i < WIDTH; i++)
-            pn[i] = 0;
-    }
-
-    explicit base_uint(const std::string& str);
-    explicit base_uint(const std::vector<unsigned char>& vch);
-
-    bool operator!() const
+    bool IsNull() const
     {
         for (int i = 0; i < WIDTH; i++)
-            if (pn[i] != 0)
+            if (data[i] != 0)
                 return false;
         return true;
     }
 
-    const base_uint operator~() const
-    {
-        base_uint ret;
-        for (int i = 0; i < WIDTH; i++)
-            ret.pn[i] = ~pn[i];
-        return ret;
-    }
-
-    const base_uint operator-() const
-    {
-        base_uint ret;
-        for (int i = 0; i < WIDTH; i++)
-            ret.pn[i] = ~pn[i];
-        ret++;
-        return ret;
-    }
-
-    double getdouble() const;
-
-    base_uint& operator=(uint64_t b)
-    {
-        pn[0] = (unsigned int)b;
-        pn[1] = (unsigned int)(b >> 32);
-        for (int i = 2; i < WIDTH; i++)
-            pn[i] = 0;
-        return *this;
-    }
-
-    base_uint& operator^=(const base_uint& b)
-    {
-        for (int i = 0; i < WIDTH; i++)
-            pn[i] ^= b.pn[i];
-        return *this;
-    }
-
-    base_uint& operator&=(const base_uint& b)
-    {
-        for (int i = 0; i < WIDTH; i++)
-            pn[i] &= b.pn[i];
-        return *this;
-    }
-
-    base_uint& operator|=(const base_uint& b)
-    {
-        for (int i = 0; i < WIDTH; i++)
-            pn[i] |= b.pn[i];
-        return *this;
-    }
-
-    base_uint& operator^=(uint64_t b)
-    {
-        pn[0] ^= (unsigned int)b;
-        pn[1] ^= (unsigned int)(b >> 32);
-        return *this;
-    }
-
-    base_uint& operator|=(uint64_t b)
-    {
-        pn[0] |= (unsigned int)b;
-        pn[1] |= (unsigned int)(b >> 32);
-        return *this;
-    }
-
-    base_uint& operator<<=(unsigned int shift);
-    base_uint& operator>>=(unsigned int shift);
-
-    base_uint& operator+=(const base_uint& b)
-    {
-        uint64_t carry = 0;
-        for (int i = 0; i < WIDTH; i++)
-        {
-            uint64_t n = carry + pn[i] + b.pn[i];
-            pn[i] = n & 0xffffffff;
-            carry = n >> 32;
-        }
-        return *this;
-    }
-
-    base_uint& operator-=(const base_uint& b)
-    {
-        *this += -b;
-        return *this;
-    }
-
-    base_uint& operator+=(uint64_t b64)
-    {
-        base_uint b;
-        b = b64;
-        *this += b;
-        return *this;
-    }
-
-    base_uint& operator-=(uint64_t b64)
-    {
-        base_uint b;
-        b = b64;
-        *this += -b;
-        return *this;
-    }
-
-    base_uint& operator*=(uint32_t b32);
-    base_uint& operator*=(const base_uint& b);
-    base_uint& operator/=(const base_uint& b);
-
-    base_uint& operator++()
-    {
-        // prefix operator
-        int i = 0;
-        while (++pn[i] == 0 && i < WIDTH-1)
-            i++;
-        return *this;
-    }
-
-    const base_uint operator++(int)
-    {
-        // postfix operator
-        const base_uint ret = *this;
-        ++(*this);
-        return ret;
-    }
-
-    base_uint& operator--()
-    {
-        // prefix operator
-        int i = 0;
-        while (--pn[i] == (uint32_t)-1 && i < WIDTH-1)
-            i++;
-        return *this;
-    }
-
-    const base_uint operator--(int)
+    void SetNull()
     {
-        // postfix operator
-        const base_uint ret = *this;
-        --(*this);
-        return ret;
+        memset(data, 0, sizeof(data));
     }
 
-    int CompareTo(const base_uint& b) const;
-    bool EqualTo(uint64_t b) const;
-
-    friend inline const base_uint operator+(const base_uint& a, const base_uint& b) { return base_uint(a) += b; }
-    friend inline const base_uint operator-(const base_uint& a, const base_uint& b) { return base_uint(a) -= b; }
-    friend inline const base_uint operator*(const base_uint& a, const base_uint& b) { return base_uint(a) *= b; }
-    friend inline const base_uint operator/(const base_uint& a, const base_uint& b) { return base_uint(a) /= b; }
-    friend inline const base_uint operator|(const base_uint& a, const base_uint& b) { return base_uint(a) |= b; }
-    friend inline const base_uint operator&(const base_uint& a, const base_uint& b) { return base_uint(a) &= b; }
-    friend inline const base_uint operator^(const base_uint& a, const base_uint& b) { return base_uint(a) ^= b; }
-    friend inline const base_uint operator>>(const base_uint& a, int shift) { return base_uint(a) >>= shift; }
-    friend inline const base_uint operator<<(const base_uint& a, int shift) { return base_uint(a) <<= shift; }
-    friend inline const base_uint operator*(const base_uint& a, uint32_t b) { return base_uint(a) *= b; }
-    friend inline bool operator==(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) == 0; }
-    friend inline bool operator!=(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) != 0; }
-    friend inline bool operator>(const base_uint& a, const base_uint& b) { return a.CompareTo(b) > 0; }
-    friend inline bool operator<(const base_uint& a, const base_uint& b) { return a.CompareTo(b) < 0; }
-    friend inline bool operator>=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) >= 0; }
-    friend inline bool operator<=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) <= 0; }
-    friend inline bool operator==(const base_uint& a, uint64_t b) { return a.EqualTo(b); }
-    friend inline bool operator!=(const base_uint& a, uint64_t b) { return !a.EqualTo(b); }
+    friend inline bool operator==(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) == 0; }
+    friend inline bool operator!=(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) != 0; }
+    friend inline bool operator<(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) < 0; }
 
     std::string GetHex() const;
     void SetHex(const char* psz);
@@ -232,122 +52,107 @@ public:
 
     unsigned char* begin()
     {
-        return (unsigned char*)&pn[0];
+        return &data[0];
     }
 
     unsigned char* end()
     {
-        return (unsigned char*)&pn[WIDTH];
+        return &data[WIDTH];
     }
 
     const unsigned char* begin() const
     {
-        return (unsigned char*)&pn[0];
+        return &data[0];
     }
 
     const unsigned char* end() const
     {
-        return (unsigned char*)&pn[WIDTH];
+        return &data[WIDTH];
     }
 
     unsigned int size() const
     {
-        return sizeof(pn);
-    }
-
-    /**
-     * Returns the position of the highest bit set plus one, or zero if the
-     * value is zero.
-     */
-    unsigned int bits() const;
-
-    uint64_t GetLow64() const
-    {
-        assert(WIDTH >= 2);
-        return pn[0] | (uint64_t)pn[1] << 32;
+        return sizeof(data);
     }
 
     unsigned int GetSerializeSize(int nType, int nVersion) const
     {
-        return sizeof(pn);
+        return sizeof(data);
     }
 
     template<typename Stream>
     void Serialize(Stream& s, int nType, int nVersion) const
     {
-        s.write((char*)pn, sizeof(pn));
+        s.write((char*)data, sizeof(data));
     }
 
     template<typename Stream>
     void Unserialize(Stream& s, int nType, int nVersion)
     {
-        s.read((char*)pn, sizeof(pn));
-    }
-
-    // Temporary for migration to opaque uint160/256
-    uint64_t GetCheapHash() const
-    {
-        return GetLow64();
-    }
-    void SetNull()
-    {
-        memset(pn, 0, sizeof(pn));
-    }
-    bool IsNull() const
-    {
-        for (int i = 0; i < WIDTH; i++)
-            if (pn[i] != 0)
-                return false;
-        return true;
+        s.read((char*)data, sizeof(data));
     }
 };
 
-/** 160-bit unsigned big integer. */
-class uint160 : public base_uint<160> {
+/** 160-bit opaque blob.
+ * @note This type is called uint160 for historical reasons only. It is an opaque
+ * blob of 160 bits and has no integer operations.
+ */
+class uint160 : public base_blob<160> {
 public:
     uint160() {}
-    uint160(const base_uint<160>& b) : base_uint<160>(b) {}
-    uint160(uint64_t b) : base_uint<160>(b) {}
-    explicit uint160(const std::string& str) : base_uint<160>(str) {}
-    explicit uint160(const std::vector<unsigned char>& vch) : base_uint<160>(vch) {}
+    uint160(const base_blob<160>& b) : base_blob<160>(b) {}
+    explicit uint160(const std::vector<unsigned char>& vch) : base_blob<160>(vch) {}
 };
 
-/** 256-bit unsigned big integer. */
-class uint256 : public base_uint<256> {
+/** 256-bit opaque blob.
+ * @note This type is called uint256 for historical reasons only. It is an
+ * opaque blob of 256 bits and has no integer operations. Use arith_uint256 if
+ * those are required.
+ */
+class uint256 : public base_blob<256> {
 public:
     uint256() {}
-    uint256(const base_uint<256>& b) : base_uint<256>(b) {}
-    uint256(uint64_t b) : base_uint<256>(b) {}
-    explicit uint256(const std::string& str) : base_uint<256>(str) {}
-    explicit uint256(const std::vector<unsigned char>& vch) : base_uint<256>(vch) {}
-    
-    /**
-     * The "compact" format is a representation of a whole
-     * number N using an unsigned 32bit number similar to a
-     * floating point format.
-     * The most significant 8 bits are the unsigned exponent of base 256.
-     * This exponent can be thought of as "number of bytes of N".
-     * The lower 23 bits are the mantissa.
-     * Bit number 24 (0x800000) represents the sign of N.
-     * N = (-1^sign) * mantissa * 256^(exponent-3)
-     * 
-     * Satoshi's original implementation used BN_bn2mpi() and BN_mpi2bn().
-     * MPI uses the most significant bit of the first byte as sign.
-     * Thus 0x1234560000 is compact (0x05123456)
-     * and  0xc0de000000 is compact (0x0600c0de)
-     * 
-     * Bitcoin only uses this "compact" format for encoding difficulty
-     * targets, which are unsigned 256bit quantities.  Thus, all the
-     * complexities of the sign bit and using base 256 are probably an
-     * implementation accident.
+    uint256(const base_blob<256>& b) : base_blob<256>(b) {}
+    explicit uint256(const std::vector<unsigned char>& vch) : base_blob<256>(vch) {}
+
+    /** A cheap hash function that just returns 64 bits from the result, it can be
+     * used when the contents are considered uniformly random. It is not appropriate
+     * when the value can easily be influenced from outside as e.g. a network adversary could
+     * provide values to trigger worst-case behavior.
+     * @note The result of this function is not stable between little and big endian.
      */
-    uint256& SetCompact(uint32_t nCompact, bool *pfNegative = NULL, bool *pfOverflow = NULL);
-    uint32_t GetCompact(bool fNegative = false) const;
+    uint64_t GetCheapHash() const
+    {
+        uint64_t result;
+        memcpy((void*)&result, (void*)data, 8);
+        return result;
+    }
 
+    /** A more secure, salted hash function.
+     * @note This hash is not stable between little and big endian.
+     */
     uint64_t GetHash(const uint256& salt) const;
 };
 
-// Temporary for migration to opaque uint160/256
-inline uint256 uint256S(const std::string &x) { return uint256(x); }
+/* uint256 from const char *.
+ * This is a separate function because the constructor uint256(const char*) can result
+ * in dangerously catching uint256(0).
+ */
+inline uint256 uint256S(const char *str)
+{
+    uint256 rv;
+    rv.SetHex(str);
+    return rv;
+}
+/* uint256 from std::string.
+ * This is a separate function because the constructor uint256(const std::string &str) can result
+ * in dangerously catching uint256(0) via std::string(const char*).
+ */
+inline uint256 uint256S(const std::string& str)
+{
+    uint256 rv;
+    rv.SetHex(str);
+    return rv;
+}
 
 #endif // BITCOIN_UINT256_H