Merge pull request #5100

99f41b9 MOVEONLY: core.o -> core/block.o (jtimon)
561e9e9 MOVEONLY: Move script/compressor out of script and put CTxOutCompressor (from core) with it (jtimon)
999a2ab MOVEONLY: separate CTxUndo out of core (jtimon)
4a3587d MOVEONLY: Separate CTransaction and dependencies from core (jtimon)
eda3733 MOVEONLY: Move CFeeRate and Amount constants to amount.o (jtimon)

41 files changed, 992 insertions, 939 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 1f8f9aabdc..91cc1b96e7 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -80,7 +80,9 @@ BITCOIN_CORE_H = \
   coincontrol.h \
   coins.h \
   compat.h \
-  core.h \
+  compressor.h \
+  core/block.h \
+  core/transaction.h \
   core_io.h \
   crypter.h \
   db.h \
@@ -103,7 +105,6 @@ BITCOIN_CORE_H = \
   rpcclient.h \
   rpcprotocol.h \
   rpcserver.h \
-  script/compressor.h \
   script/interpreter.h \
   script/script.h \
   script/sigcache.h \
@@ -119,6 +120,7 @@ BITCOIN_CORE_H = \
   txmempool.h \
   ui_interface.h \
   uint256.h \
+  undo.h \
   util.h \
   utilstrencodings.h \
   utilmoneystr.h \
@@ -209,10 +211,13 @@ univalue_libbitcoin_univalue_a_SOURCES = \
 libbitcoin_common_a_CPPFLAGS = $(BITCOIN_INCLUDES)
 libbitcoin_common_a_SOURCES = \
   allocators.cpp \
+  amount.cpp \
   base58.cpp \
   chainparams.cpp \
   coins.cpp \
-  core.cpp \
+  compressor.cpp \
+  core/block.cpp \
+  core/transaction.cpp \
   core_read.cpp \
   core_write.cpp \
   ecwrapper.cpp \
@@ -221,7 +226,6 @@ libbitcoin_common_a_SOURCES = \
   keystore.cpp \
   netbase.cpp \
   protocol.cpp \
-  script/compressor.cpp \
   script/interpreter.cpp \
   script/script.cpp \
   script/sigcache.cpp \
diff --git a/src/amount.cpp b/src/amount.cpp
new file mode 100644
index 0000000000..e6f5b7d440
--- /dev/null
+++ b/src/amount.cpp
@@ -0,0 +1,31 @@
+// 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 "amount.h"
+
+#include "tinyformat.h"
+
+CFeeRate::CFeeRate(const CAmount& nFeePaid, size_t nSize)
+{
+    if (nSize > 0)
+        nSatoshisPerK = nFeePaid*1000/nSize;
+    else
+        nSatoshisPerK = 0;
+}
+
+CAmount CFeeRate::GetFee(size_t nSize) const
+{
+    CAmount nFee = nSatoshisPerK*nSize / 1000;
+
+    if (nFee == 0 && nSatoshisPerK > 0)
+        nFee = nSatoshisPerK;
+
+    return nFee;
+}
+
+std::string CFeeRate::ToString() const
+{
+    return strprintf("%d.%08d BTC/kB", nSatoshisPerK / COIN, nSatoshisPerK % COIN);
+}
diff --git a/src/amount.h b/src/amount.h
index 831fa1f6ca..c0d37954cb 100644
--- a/src/amount.h
+++ b/src/amount.h
@@ -6,8 +6,49 @@
 #ifndef BITCOIN_AMOUNT_H
 #define BITCOIN_AMOUNT_H
 
-#include <stdint.h>
+#include "serialize.h"
+
+#include <stdlib.h>
+#include <string>
 
 typedef int64_t CAmount;
 
+static const CAmount COIN = 100000000;
+static const CAmount CENT = 1000000;
+
+/** No amount larger than this (in satoshi) is valid */
+static const CAmount MAX_MONEY = 21000000 * COIN;
+inline bool MoneyRange(const CAmount& nValue) { return (nValue >= 0 && nValue <= MAX_MONEY); }
+
+/** Type-safe wrapper class to for fee rates
+ * (how much to pay based on transaction size)
+ */
+class CFeeRate
+{
+private:
+    CAmount nSatoshisPerK; // unit is satoshis-per-1,000-bytes
+public:
+    CFeeRate() : nSatoshisPerK(0) { }
+    explicit CFeeRate(const CAmount& _nSatoshisPerK): nSatoshisPerK(_nSatoshisPerK) { }
+    CFeeRate(const CAmount& nFeePaid, size_t nSize);
+    CFeeRate(const CFeeRate& other) { nSatoshisPerK = other.nSatoshisPerK; }
+
+    CAmount GetFee(size_t size) const; // unit returned is satoshis
+    CAmount GetFeePerK() const { return GetFee(1000); } // satoshis-per-1000-bytes
+
+    friend bool operator<(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK < b.nSatoshisPerK; }
+    friend bool operator>(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK > b.nSatoshisPerK; }
+    friend bool operator==(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK == b.nSatoshisPerK; }
+    friend bool operator<=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK <= b.nSatoshisPerK; }
+    friend bool operator>=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK >= b.nSatoshisPerK; }
+    std::string ToString() const;
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(nSatoshisPerK);
+    }
+};
+
 #endif //  BITCOIN_AMOUNT_H
diff --git a/src/bitcoin-tx.cpp b/src/bitcoin-tx.cpp
index da37e60c7f..6f3409edf3 100644
--- a/src/bitcoin-tx.cpp
+++ b/src/bitcoin-tx.cpp
@@ -3,7 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "base58.h"
-#include "core.h"
+#include "core/transaction.h"
 #include "core_io.h"
 #include "keystore.h"
 #include "main.h" // for MAX_BLOCK_SIZE
diff --git a/src/bloom.cpp b/src/bloom.cpp
index cac71fdbbf..c1e7aeb3bf 100644
--- a/src/bloom.cpp
+++ b/src/bloom.cpp
@@ -4,7 +4,7 @@
 
 #include "bloom.h"
 
-#include "core.h"
+#include "core/transaction.h"
 #include "script/script.h"
 #include "script/standard.h"
 #include "streams.h"
diff --git a/src/chain.h b/src/chain.h
index 290150476e..2a55771622 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -6,7 +6,7 @@
 #ifndef H_BITCOIN_CHAIN
 #define H_BITCOIN_CHAIN
 
-#include "core.h"
+#include "core/block.h"
 #include "pow.h"
 #include "tinyformat.h"
 #include "uint256.h"
diff --git a/src/chainparams.h b/src/chainparams.h
index f157419bb2..e27728dbd5 100644
--- a/src/chainparams.h
+++ b/src/chainparams.h
@@ -6,9 +6,9 @@
 #ifndef BITCOIN_CHAIN_PARAMS_H
 #define BITCOIN_CHAIN_PARAMS_H
 
-#include "core.h"
 #include "chainparamsbase.h"
 #include "checkpoints.h"
+#include "core/block.h"
 #include "protocol.h"
 #include "uint256.h"
 
diff --git a/src/coincontrol.h b/src/coincontrol.h
index 033092c019..c8f12d92de 100644
--- a/src/coincontrol.h
+++ b/src/coincontrol.h
@@ -5,7 +5,7 @@
 #ifndef COINCONTROL_H
 #define COINCONTROL_H
 
-#include "core.h"
+#include "core/transaction.h"
 
 /** Coin Control Features. */
 class CCoinControl
diff --git a/src/coins.h b/src/coins.h
index b8f1e5bcc5..ee9051562b 100644
--- a/src/coins.h
+++ b/src/coins.h
@@ -6,9 +6,10 @@
 #ifndef BITCOIN_COINS_H
 #define BITCOIN_COINS_H
 
-#include "core.h"
+#include "compressor.h"
 #include "serialize.h"
 #include "uint256.h"
+#include "undo.h"
 
 #include <assert.h>
 #include <stdint.h>
diff --git a/src/script/compressor.cpp b/src/compressor.cpp
index af1acf48db..806175dd3e 100644
--- a/src/script/compressor.cpp
+++ b/src/compressor.cpp
@@ -5,6 +5,7 @@
 
 #include "compressor.h"
 
+#include "hash.h"
 #include "key.h"
 #include "script/standard.h"
 
@@ -128,3 +129,57 @@ bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigne
     }
     return false;
 }
+
+// Amount compression:
+// * If the amount is 0, output 0
+// * first, divide the amount (in base units) by the largest power of 10 possible; call the exponent e (e is max 9)
+// * if e<9, the last digit of the resulting number cannot be 0; store it as d, and drop it (divide by 10)
+//   * call the result n
+//   * output 1 + 10*(9*n + d - 1) + e
+// * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9
+// (this is decodable, as d is in [1-9] and e is in [0-9])
+
+uint64_t CTxOutCompressor::CompressAmount(uint64_t n)
+{
+    if (n == 0)
+        return 0;
+    int e = 0;
+    while (((n % 10) == 0) && e < 9) {
+        n /= 10;
+        e++;
+    }
+    if (e < 9) {
+        int d = (n % 10);
+        assert(d >= 1 && d <= 9);
+        n /= 10;
+        return 1 + (n*9 + d - 1)*10 + e;
+    } else {
+        return 1 + (n - 1)*10 + 9;
+    }
+}
+
+uint64_t CTxOutCompressor::DecompressAmount(uint64_t x)
+{
+    // x = 0  OR  x = 1+10*(9*n + d - 1) + e  OR  x = 1+10*(n - 1) + 9
+    if (x == 0)
+        return 0;
+    x--;
+    // x = 10*(9*n + d - 1) + e
+    int e = x % 10;
+    x /= 10;
+    uint64_t n = 0;
+    if (e < 9) {
+        // x = 9*n + d - 1
+        int d = (x % 9) + 1;
+        x /= 9;
+        // x = n
+        n = x*10 + d;
+    } else {
+        n = x+1;
+    }
+    while (e) {
+        n *= 10;
+        e--;
+    }
+    return n;
+}
diff --git a/src/script/compressor.h b/src/compressor.h
index 154e0b2662..a612c3a883 100644
--- a/src/script/compressor.h
+++ b/src/compressor.h
@@ -3,9 +3,10 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#ifndef H_BITCOIN_SCRIPT_COMPRESSOR
-#define H_BITCOIN_SCRIPT_COMPRESSOR
+#ifndef H_BITCOIN_COMPRESSOR
+#define H_BITCOIN_COMPRESSOR
 
+#include "core/transaction.h"
 #include "script/script.h"
 #include "serialize.h"
 
@@ -86,4 +87,33 @@ public:
     }
 };
 
-#endif // H_BITCOIN_SCRIPT_COMPRESSOR
+/** wrapper for CTxOut that provides a more compact serialization */
+class CTxOutCompressor
+{
+private:
+    CTxOut &txout;
+
+public:
+    static uint64_t CompressAmount(uint64_t nAmount);
+    static uint64_t DecompressAmount(uint64_t nAmount);
+
+    CTxOutCompressor(CTxOut &txoutIn) : txout(txoutIn) { }
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        if (!ser_action.ForRead()) {
+            uint64_t nVal = CompressAmount(txout.nValue);
+            READWRITE(VARINT(nVal));
+        } else {
+            uint64_t nVal = 0;
+            READWRITE(VARINT(nVal));
+            txout.nValue = DecompressAmount(nVal);
+        }
+        CScriptCompressor cscript(REF(txout.scriptPubKey));
+        READWRITE(cscript);
+    }
+};
+
+#endif // H_BITCOIN_COMPRESSOR
diff --git a/src/core.cpp b/src/core.cpp
deleted file mode 100644
index 73e6de88e1..0000000000
--- a/src/core.cpp
+++ /dev/null
@@ -1,339 +0,0 @@
-// Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2014 The Bitcoin developers
-// Distributed under the MIT/X11 software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#include "core.h"
-
-#include "hash.h"
-#include "tinyformat.h"
-#include "utilstrencodings.h"
-
-std::string COutPoint::ToString() const
-{
-    return strprintf("COutPoint(%s, %u)", hash.ToString().substr(0,10), n);
-}
-
-CTxIn::CTxIn(COutPoint prevoutIn, CScript scriptSigIn, uint32_t nSequenceIn)
-{
-    prevout = prevoutIn;
-    scriptSig = scriptSigIn;
-    nSequence = nSequenceIn;
-}
-
-CTxIn::CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn, uint32_t nSequenceIn)
-{
-    prevout = COutPoint(hashPrevTx, nOut);
-    scriptSig = scriptSigIn;
-    nSequence = nSequenceIn;
-}
-
-std::string CTxIn::ToString() const
-{
-    std::string str;
-    str += "CTxIn(";
-    str += prevout.ToString();
-    if (prevout.IsNull())
-        str += strprintf(", coinbase %s", HexStr(scriptSig));
-    else
-        str += strprintf(", scriptSig=%s", scriptSig.ToString().substr(0,24));
-    if (nSequence != std::numeric_limits<unsigned int>::max())
-        str += strprintf(", nSequence=%u", nSequence);
-    str += ")";
-    return str;
-}
-
-CTxOut::CTxOut(const CAmount& nValueIn, CScript scriptPubKeyIn)
-{
-    nValue = nValueIn;
-    scriptPubKey = scriptPubKeyIn;
-}
-
-uint256 CTxOut::GetHash() const
-{
-    return SerializeHash(*this);
-}
-
-std::string CTxOut::ToString() const
-{
-    return strprintf("CTxOut(nValue=%d.%08d, scriptPubKey=%s)", nValue / COIN, nValue % COIN, scriptPubKey.ToString().substr(0,30));
-}
-
-CFeeRate::CFeeRate(const CAmount& nFeePaid, size_t nSize)
-{
-    if (nSize > 0)
-        nSatoshisPerK = nFeePaid*1000/nSize;
-    else
-        nSatoshisPerK = 0;
-}
-
-CAmount CFeeRate::GetFee(size_t nSize) const
-{
-    CAmount nFee = nSatoshisPerK*nSize / 1000;
-
-    if (nFee == 0 && nSatoshisPerK > 0)
-        nFee = nSatoshisPerK;
-
-    return nFee;
-}
-
-std::string CFeeRate::ToString() const
-{
-    return strprintf("%d.%08d BTC/kB", nSatoshisPerK / COIN, nSatoshisPerK % COIN);
-}
-
-CMutableTransaction::CMutableTransaction() : nVersion(CTransaction::CURRENT_VERSION), nLockTime(0) {}
-CMutableTransaction::CMutableTransaction(const CTransaction& tx) : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout), nLockTime(tx.nLockTime) {}
-
-uint256 CMutableTransaction::GetHash() const
-{
-    return SerializeHash(*this);
-}
-
-void CTransaction::UpdateHash() const
-{
-    *const_cast<uint256*>(&hash) = SerializeHash(*this);
-}
-
-CTransaction::CTransaction() : hash(0), nVersion(CTransaction::CURRENT_VERSION), vin(), vout(), nLockTime(0) { }
-
-CTransaction::CTransaction(const CMutableTransaction &tx) : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout), nLockTime(tx.nLockTime) {
-    UpdateHash();
-}
-
-CTransaction& CTransaction::operator=(const CTransaction &tx) {
-    *const_cast<int*>(&nVersion) = tx.nVersion;
-    *const_cast<std::vector<CTxIn>*>(&vin) = tx.vin;
-    *const_cast<std::vector<CTxOut>*>(&vout) = tx.vout;
-    *const_cast<unsigned int*>(&nLockTime) = tx.nLockTime;
-    *const_cast<uint256*>(&hash) = tx.hash;
-    return *this;
-}
-
-CAmount CTransaction::GetValueOut() const
-{
-    CAmount nValueOut = 0;
-    for (std::vector<CTxOut>::const_iterator it(vout.begin()); it != vout.end(); ++it)
-    {
-        nValueOut += it->nValue;
-        if (!MoneyRange(it->nValue) || !MoneyRange(nValueOut))
-            throw std::runtime_error("CTransaction::GetValueOut() : value out of range");
-    }
-    return nValueOut;
-}
-
-double CTransaction::ComputePriority(double dPriorityInputs, unsigned int nTxSize) const
-{
-    nTxSize = CalculateModifiedSize(nTxSize);
-    if (nTxSize == 0) return 0.0;
-
-    return dPriorityInputs / nTxSize;
-}
-
-unsigned int CTransaction::CalculateModifiedSize(unsigned int nTxSize) const
-{
-    // In order to avoid disincentivizing cleaning up the UTXO set we don't count
-    // the constant overhead for each txin and up to 110 bytes of scriptSig (which
-    // is enough to cover a compressed pubkey p2sh redemption) for priority.
-    // Providing any more cleanup incentive than making additional inputs free would
-    // risk encouraging people to create junk outputs to redeem later.
-    if (nTxSize == 0)
-        nTxSize = ::GetSerializeSize(*this, SER_NETWORK, PROTOCOL_VERSION);
-    for (std::vector<CTxIn>::const_iterator it(vin.begin()); it != vin.end(); ++it)
-    {
-        unsigned int offset = 41U + std::min(110U, (unsigned int)it->scriptSig.size());
-        if (nTxSize > offset)
-            nTxSize -= offset;
-    }
-    return nTxSize;
-}
-
-std::string CTransaction::ToString() const
-{
-    std::string str;
-    str += strprintf("CTransaction(hash=%s, ver=%d, vin.size=%u, vout.size=%u, nLockTime=%u)\n",
-        GetHash().ToString().substr(0,10),
-        nVersion,
-        vin.size(),
-        vout.size(),
-        nLockTime);
-    for (unsigned int i = 0; i < vin.size(); i++)
-        str += "    " + vin[i].ToString() + "\n";
-    for (unsigned int i = 0; i < vout.size(); i++)
-        str += "    " + vout[i].ToString() + "\n";
-    return str;
-}
-
-// Amount compression:
-// * If the amount is 0, output 0
-// * first, divide the amount (in base units) by the largest power of 10 possible; call the exponent e (e is max 9)
-// * if e<9, the last digit of the resulting number cannot be 0; store it as d, and drop it (divide by 10)
-//   * call the result n
-//   * output 1 + 10*(9*n + d - 1) + e
-// * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9
-// (this is decodable, as d is in [1-9] and e is in [0-9])
-
-uint64_t CTxOutCompressor::CompressAmount(uint64_t n)
-{
-    if (n == 0)
-        return 0;
-    int e = 0;
-    while (((n % 10) == 0) && e < 9) {
-        n /= 10;
-        e++;
-    }
-    if (e < 9) {
-        int d = (n % 10);
-        assert(d >= 1 && d <= 9);
-        n /= 10;
-        return 1 + (n*9 + d - 1)*10 + e;
-    } else {
-        return 1 + (n - 1)*10 + 9;
-    }
-}
-
-uint64_t CTxOutCompressor::DecompressAmount(uint64_t x)
-{
-    // x = 0  OR  x = 1+10*(9*n + d - 1) + e  OR  x = 1+10*(n - 1) + 9
-    if (x == 0)
-        return 0;
-    x--;
-    // x = 10*(9*n + d - 1) + e
-    int e = x % 10;
-    x /= 10;
-    uint64_t n = 0;
-    if (e < 9) {
-        // x = 9*n + d - 1
-        int d = (x % 9) + 1;
-        x /= 9;
-        // x = n
-        n = x*10 + d;
-    } else {
-        n = x+1;
-    }
-    while (e) {
-        n *= 10;
-        e--;
-    }
-    return n;
-}
-
-uint256 CBlockHeader::GetHash() const
-{
-    return Hash(BEGIN(nVersion), END(nNonce));
-}
-
-uint256 CBlock::BuildMerkleTree(bool* fMutated) const
-{
-    /* WARNING! If you're reading this because you're learning about crypto
-       and/or designing a new system that will use merkle trees, keep in mind
-       that the following merkle tree algorithm has a serious flaw related to
-       duplicate txids, resulting in a vulnerability (CVE-2012-2459).
-
-       The reason is that if the number of hashes in the list at a given time
-       is odd, the last one is duplicated before computing the next level (which
-       is unusual in Merkle trees). This results in certain sequences of
-       transactions leading to the same merkle root. For example, these two
-       trees:
-
-                    A               A
-                  /  \            /   \
-                B     C         B       C
-               / \    |        / \     / \
-              D   E   F       D   E   F   F
-             / \ / \ / \     / \ / \ / \ / \
-             1 2 3 4 5 6     1 2 3 4 5 6 5 6
-
-       for transaction lists [1,2,3,4,5,6] and [1,2,3,4,5,6,5,6] (where 5 and
-       6 are repeated) result in the same root hash A (because the hash of both
-       of (F) and (F,F) is C).
-
-       The vulnerability results from being able to send a block with such a
-       transaction list, with the same merkle root, and the same block hash as
-       the original without duplication, resulting in failed validation. If the
-       receiving node proceeds to mark that block as permanently invalid
-       however, it will fail to accept further unmodified (and thus potentially
-       valid) versions of the same block. We defend against this by detecting
-       the case where we would hash two identical hashes at the end of the list
-       together, and treating that identically to the block having an invalid
-       merkle root. Assuming no double-SHA256 collisions, this will detect all
-       known ways of changing the transactions without affecting the merkle
-       root.
-    */
-    vMerkleTree.clear();
-    vMerkleTree.reserve(vtx.size() * 2 + 16); // Safe upper bound for the number of total nodes.
-    for (std::vector<CTransaction>::const_iterator it(vtx.begin()); it != vtx.end(); ++it)
-        vMerkleTree.push_back(it->GetHash());
-    int j = 0;
-    bool mutated = false;
-    for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
-    {
-        for (int i = 0; i < nSize; i += 2)
-        {
-            int i2 = std::min(i+1, nSize-1);
-            if (i2 == i + 1 && i2 + 1 == nSize && vMerkleTree[j+i] == vMerkleTree[j+i2]) {
-                // Two identical hashes at the end of the list at a particular level.
-                mutated = true;
-            }
-            vMerkleTree.push_back(Hash(BEGIN(vMerkleTree[j+i]),  END(vMerkleTree[j+i]),
-                                       BEGIN(vMerkleTree[j+i2]), END(vMerkleTree[j+i2])));
-        }
-        j += nSize;
-    }
-    if (fMutated) {
-        *fMutated = mutated;
-    }
-    return (vMerkleTree.empty() ? 0 : vMerkleTree.back());
-}
-
-std::vector<uint256> CBlock::GetMerkleBranch(int nIndex) const
-{
-    if (vMerkleTree.empty())
-        BuildMerkleTree();
-    std::vector<uint256> vMerkleBranch;
-    int j = 0;
-    for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
-    {
-        int i = std::min(nIndex^1, nSize-1);
-        vMerkleBranch.push_back(vMerkleTree[j+i]);
-        nIndex >>= 1;
-        j += nSize;
-    }
-    return vMerkleBranch;
-}
-
-uint256 CBlock::CheckMerkleBranch(uint256 hash, const std::vector<uint256>& vMerkleBranch, int nIndex)
-{
-    if (nIndex == -1)
-        return 0;
-    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;
-}
-
-std::string CBlock::ToString() const
-{
-    std::stringstream s;
-    s << strprintf("CBlock(hash=%s, ver=%d, hashPrevBlock=%s, hashMerkleRoot=%s, nTime=%u, nBits=%08x, nNonce=%u, vtx=%u)\n",
-        GetHash().ToString(),
-        nVersion,
-        hashPrevBlock.ToString(),
-        hashMerkleRoot.ToString(),
-        nTime, nBits, nNonce,
-        vtx.size());
-    for (unsigned int i = 0; i < vtx.size(); i++)
-    {
-        s << "  " << vtx[i].ToString() << "\n";
-    }
-    s << "  vMerkleTree: ";
-    for (unsigned int i = 0; i < vMerkleTree.size(); i++)
-        s << " " << vMerkleTree[i].ToString();
-    s << "\n";
-    return s.str();
-}
diff --git a/src/core.h b/src/core.h
deleted file mode 100644
index a024dad740..0000000000
--- a/src/core.h
+++ /dev/null
@@ -1,566 +0,0 @@
-// Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2013 The Bitcoin developers
-// Distributed under the MIT/X11 software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#ifndef BITCOIN_CORE_H
-#define BITCOIN_CORE_H
-
-#include "amount.h"
-#include "script/compressor.h"
-#include "script/script.h"
-#include "serialize.h"
-#include "uint256.h"
-
-#include <stdint.h>
-
-class CTransaction;
-
-static const int64_t COIN = 100000000;
-static const int64_t CENT = 1000000;
-
-/** No amount larger than this (in satoshi) is valid */
-static const CAmount MAX_MONEY = 21000000 * COIN;
-inline bool MoneyRange(const CAmount& nValue) { return (nValue >= 0 && nValue <= MAX_MONEY); }
-
-/** An outpoint - a combination of a transaction hash and an index n into its vout */
-class COutPoint
-{
-public:
-    uint256 hash;
-    uint32_t n;
-
-    COutPoint() { SetNull(); }
-    COutPoint(uint256 hashIn, uint32_t nIn) { hash = hashIn; n = nIn; }
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(FLATDATA(*this));
-    }
-
-    void SetNull() { hash = 0; n = (uint32_t) -1; }
-    bool IsNull() const { return (hash == 0 && n == (uint32_t) -1); }
-
-    friend bool operator<(const COutPoint& a, const COutPoint& b)
-    {
-        return (a.hash < b.hash || (a.hash == b.hash && a.n < b.n));
-    }
-
-    friend bool operator==(const COutPoint& a, const COutPoint& b)
-    {
-        return (a.hash == b.hash && a.n == b.n);
-    }
-
-    friend bool operator!=(const COutPoint& a, const COutPoint& b)
-    {
-        return !(a == b);
-    }
-
-    std::string ToString() const;
-};
-
-/** An input of a transaction.  It contains the location of the previous
- * transaction's output that it claims and a signature that matches the
- * output's public key.
- */
-class CTxIn
-{
-public:
-    COutPoint prevout;
-    CScript scriptSig;
-    uint32_t nSequence;
-
-    CTxIn()
-    {
-        nSequence = std::numeric_limits<unsigned int>::max();
-    }
-
-    explicit CTxIn(COutPoint prevoutIn, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=std::numeric_limits<unsigned int>::max());
-    CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=std::numeric_limits<uint32_t>::max());
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(prevout);
-        READWRITE(scriptSig);
-        READWRITE(nSequence);
-    }
-
-    bool IsFinal() const
-    {
-        return (nSequence == std::numeric_limits<uint32_t>::max());
-    }
-
-    friend bool operator==(const CTxIn& a, const CTxIn& b)
-    {
-        return (a.prevout   == b.prevout &&
-                a.scriptSig == b.scriptSig &&
-                a.nSequence == b.nSequence);
-    }
-
-    friend bool operator!=(const CTxIn& a, const CTxIn& b)
-    {
-        return !(a == b);
-    }
-
-    std::string ToString() const;
-};
-
-
-
-/** Type-safe wrapper class to for fee rates
- * (how much to pay based on transaction size)
- */
-class CFeeRate
-{
-private:
-    CAmount nSatoshisPerK; // unit is satoshis-per-1,000-bytes
-public:
-    CFeeRate() : nSatoshisPerK(0) { }
-    explicit CFeeRate(const CAmount& _nSatoshisPerK): nSatoshisPerK(_nSatoshisPerK) { }
-    CFeeRate(const CAmount& nFeePaid, size_t nSize);
-    CFeeRate(const CFeeRate& other) { nSatoshisPerK = other.nSatoshisPerK; }
-
-    CAmount GetFee(size_t size) const; // unit returned is satoshis
-    CAmount GetFeePerK() const { return GetFee(1000); } // satoshis-per-1000-bytes
-
-    friend bool operator<(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK < b.nSatoshisPerK; }
-    friend bool operator>(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK > b.nSatoshisPerK; }
-    friend bool operator==(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK == b.nSatoshisPerK; }
-    friend bool operator<=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK <= b.nSatoshisPerK; }
-    friend bool operator>=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK >= b.nSatoshisPerK; }
-    std::string ToString() const;
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(nSatoshisPerK);
-    }
-};
-
-
-/** An output of a transaction.  It contains the public key that the next input
- * must be able to sign with to claim it.
- */
-class CTxOut
-{
-public:
-    CAmount nValue;
-    CScript scriptPubKey;
-
-    CTxOut()
-    {
-        SetNull();
-    }
-
-    CTxOut(const CAmount& nValueIn, CScript scriptPubKeyIn);
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(nValue);
-        READWRITE(scriptPubKey);
-    }
-
-    void SetNull()
-    {
-        nValue = -1;
-        scriptPubKey.clear();
-    }
-
-    bool IsNull() const
-    {
-        return (nValue == -1);
-    }
-
-    uint256 GetHash() const;
-
-    bool IsDust(CFeeRate minRelayTxFee) const
-    {
-        // "Dust" is defined in terms of CTransaction::minRelayTxFee,
-        // which has units satoshis-per-kilobyte.
-        // If you'd pay more than 1/3 in fees
-        // to spend something, then we consider it dust.
-        // A typical txout is 34 bytes big, and will
-        // need a CTxIn of at least 148 bytes to spend:
-        // so dust is a txout less than 546 satoshis 
-        // with default minRelayTxFee.
-        size_t nSize = GetSerializeSize(SER_DISK,0)+148u;
-        return (nValue < 3*minRelayTxFee.GetFee(nSize));
-    }
-
-    friend bool operator==(const CTxOut& a, const CTxOut& b)
-    {
-        return (a.nValue       == b.nValue &&
-                a.scriptPubKey == b.scriptPubKey);
-    }
-
-    friend bool operator!=(const CTxOut& a, const CTxOut& b)
-    {
-        return !(a == b);
-    }
-
-    std::string ToString() const;
-};
-
-
-struct CMutableTransaction;
-
-/** The basic transaction that is broadcasted on the network and contained in
- * blocks.  A transaction can contain multiple inputs and outputs.
- */
-class CTransaction
-{
-private:
-    /** Memory only. */
-    const uint256 hash;
-    void UpdateHash() const;
-
-public:
-    static const int32_t CURRENT_VERSION=1;
-
-    // The local variables are made const to prevent unintended modification
-    // without updating the cached hash value. However, CTransaction is not
-    // actually immutable; deserialization and assignment are implemented,
-    // and bypass the constness. This is safe, as they update the entire
-    // structure, including the hash.
-    const int32_t nVersion;
-    const std::vector<CTxIn> vin;
-    const std::vector<CTxOut> vout;
-    const uint32_t nLockTime;
-
-    /** Construct a CTransaction that qualifies as IsNull() */
-    CTransaction();
-
-    /** Convert a CMutableTransaction into a CTransaction. */
-    CTransaction(const CMutableTransaction &tx);
-
-    CTransaction& operator=(const CTransaction& tx);
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(*const_cast<int32_t*>(&this->nVersion));
-        nVersion = this->nVersion;
-        READWRITE(*const_cast<std::vector<CTxIn>*>(&vin));
-        READWRITE(*const_cast<std::vector<CTxOut>*>(&vout));
-        READWRITE(*const_cast<uint32_t*>(&nLockTime));
-        if (ser_action.ForRead())
-            UpdateHash();
-    }
-
-    bool IsNull() const {
-        return vin.empty() && vout.empty();
-    }
-
-    const uint256& GetHash() const {
-        return hash;
-    }
-
-    // Return sum of txouts.
-    CAmount GetValueOut() const;
-    // GetValueIn() is a method on CCoinsViewCache, because
-    // inputs must be known to compute value in.
-
-    // Compute priority, given priority of inputs and (optionally) tx size
-    double ComputePriority(double dPriorityInputs, unsigned int nTxSize=0) const;
-
-    // Compute modified tx size for priority calculation (optionally given tx size)
-    unsigned int CalculateModifiedSize(unsigned int nTxSize=0) const;
-
-    bool IsCoinBase() const
-    {
-        return (vin.size() == 1 && vin[0].prevout.IsNull());
-    }
-
-    friend bool operator==(const CTransaction& a, const CTransaction& b)
-    {
-        return a.hash == b.hash;
-    }
-
-    friend bool operator!=(const CTransaction& a, const CTransaction& b)
-    {
-        return a.hash != b.hash;
-    }
-
-    std::string ToString() const;
-};
-
-/** A mutable version of CTransaction. */
-struct CMutableTransaction
-{
-    int32_t nVersion;
-    std::vector<CTxIn> vin;
-    std::vector<CTxOut> vout;
-    uint32_t nLockTime;
-
-    CMutableTransaction();
-    CMutableTransaction(const CTransaction& tx);
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(this->nVersion);
-        nVersion = this->nVersion;
-        READWRITE(vin);
-        READWRITE(vout);
-        READWRITE(nLockTime);
-    }
-
-    /** Compute the hash of this CMutableTransaction. This is computed on the
-     * fly, as opposed to GetHash() in CTransaction, which uses a cached result.
-     */
-    uint256 GetHash() const;
-};
-
-/** wrapper for CTxOut that provides a more compact serialization */
-class CTxOutCompressor
-{
-private:
-    CTxOut &txout;
-
-public:
-    static uint64_t CompressAmount(uint64_t nAmount);
-    static uint64_t DecompressAmount(uint64_t nAmount);
-
-    CTxOutCompressor(CTxOut &txoutIn) : txout(txoutIn) { }
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        if (!ser_action.ForRead()) {
-            uint64_t nVal = CompressAmount(txout.nValue);
-            READWRITE(VARINT(nVal));
-        } else {
-            uint64_t nVal = 0;
-            READWRITE(VARINT(nVal));
-            txout.nValue = DecompressAmount(nVal);
-        }
-        CScriptCompressor cscript(REF(txout.scriptPubKey));
-        READWRITE(cscript);
-    }
-};
-
-/** Undo information for a CTxIn
- *
- *  Contains the prevout's CTxOut being spent, and if this was the
- *  last output of the affected transaction, its metadata as well
- *  (coinbase or not, height, transaction version)
- */
-class CTxInUndo
-{
-public:
-    CTxOut txout;         // the txout data before being spent
-    bool fCoinBase;       // if the outpoint was the last unspent: whether it belonged to a coinbase
-    unsigned int nHeight; // if the outpoint was the last unspent: its height
-    int nVersion;         // if the outpoint was the last unspent: its version
-
-    CTxInUndo() : txout(), fCoinBase(false), nHeight(0), nVersion(0) {}
-    CTxInUndo(const CTxOut &txoutIn, bool fCoinBaseIn = false, unsigned int nHeightIn = 0, int nVersionIn = 0) : txout(txoutIn), fCoinBase(fCoinBaseIn), nHeight(nHeightIn), nVersion(nVersionIn) { }
-
-    unsigned int GetSerializeSize(int nType, int nVersion) const {
-        return ::GetSerializeSize(VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion) +
-               (nHeight > 0 ? ::GetSerializeSize(VARINT(this->nVersion), nType, nVersion) : 0) +
-               ::GetSerializeSize(CTxOutCompressor(REF(txout)), nType, nVersion);
-    }
-
-    template<typename Stream>
-    void Serialize(Stream &s, int nType, int nVersion) const {
-        ::Serialize(s, VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion);
-        if (nHeight > 0)
-            ::Serialize(s, VARINT(this->nVersion), nType, nVersion);
-        ::Serialize(s, CTxOutCompressor(REF(txout)), nType, nVersion);
-    }
-
-    template<typename Stream>
-    void Unserialize(Stream &s, int nType, int nVersion) {
-        unsigned int nCode = 0;
-        ::Unserialize(s, VARINT(nCode), nType, nVersion);
-        nHeight = nCode / 2;
-        fCoinBase = nCode & 1;
-        if (nHeight > 0)
-            ::Unserialize(s, VARINT(this->nVersion), nType, nVersion);
-        ::Unserialize(s, REF(CTxOutCompressor(REF(txout))), nType, nVersion);
-    }
-};
-
-/** Undo information for a CTransaction */
-class CTxUndo
-{
-public:
-    // undo information for all txins
-    std::vector<CTxInUndo> vprevout;
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(vprevout);
-    }
-};
-
-
-/** Nodes collect new transactions into a block, hash them into a hash tree,
- * and scan through nonce values to make the block's hash satisfy proof-of-work
- * requirements.  When they solve the proof-of-work, they broadcast the block
- * to everyone and the block is added to the block chain.  The first transaction
- * in the block is a special one that creates a new coin owned by the creator
- * of the block.
- */
-class CBlockHeader
-{
-public:
-    // header
-    static const int32_t CURRENT_VERSION=2;
-    int32_t nVersion;
-    uint256 hashPrevBlock;
-    uint256 hashMerkleRoot;
-    uint32_t nTime;
-    uint32_t nBits;
-    uint32_t nNonce;
-
-    CBlockHeader()
-    {
-        SetNull();
-    }
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(this->nVersion);
-        nVersion = this->nVersion;
-        READWRITE(hashPrevBlock);
-        READWRITE(hashMerkleRoot);
-        READWRITE(nTime);
-        READWRITE(nBits);
-        READWRITE(nNonce);
-    }
-
-    void SetNull()
-    {
-        nVersion = CBlockHeader::CURRENT_VERSION;
-        hashPrevBlock = 0;
-        hashMerkleRoot = 0;
-        nTime = 0;
-        nBits = 0;
-        nNonce = 0;
-    }
-
-    bool IsNull() const
-    {
-        return (nBits == 0);
-    }
-
-    uint256 GetHash() const;
-
-    int64_t GetBlockTime() const
-    {
-        return (int64_t)nTime;
-    }
-};
-
-
-class CBlock : public CBlockHeader
-{
-public:
-    // network and disk
-    std::vector<CTransaction> vtx;
-
-    // memory only
-    mutable std::vector<uint256> vMerkleTree;
-
-    CBlock()
-    {
-        SetNull();
-    }
-
-    CBlock(const CBlockHeader &header)
-    {
-        SetNull();
-        *((CBlockHeader*)this) = header;
-    }
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(*(CBlockHeader*)this);
-        READWRITE(vtx);
-    }
-
-    void SetNull()
-    {
-        CBlockHeader::SetNull();
-        vtx.clear();
-        vMerkleTree.clear();
-    }
-
-    CBlockHeader GetBlockHeader() const
-    {
-        CBlockHeader block;
-        block.nVersion       = nVersion;
-        block.hashPrevBlock  = hashPrevBlock;
-        block.hashMerkleRoot = hashMerkleRoot;
-        block.nTime          = nTime;
-        block.nBits          = nBits;
-        block.nNonce         = nNonce;
-        return block;
-    }
-
-    // Build the in-memory merkle tree for this block and return the merkle root.
-    // If non-NULL, *mutated is set to whether mutation was detected in the merkle
-    // tree (a duplication of transactions in the block leading to an identical
-    // merkle root).
-    uint256 BuildMerkleTree(bool* mutated = NULL) const;
-
-    std::vector<uint256> GetMerkleBranch(int nIndex) const;
-    static uint256 CheckMerkleBranch(uint256 hash, const std::vector<uint256>& vMerkleBranch, int nIndex);
-    std::string ToString() const;
-};
-
-
-/** Describes a place in the block chain to another node such that if the
- * other node doesn't have the same branch, it can find a recent common trunk.
- * The further back it is, the further before the fork it may be.
- */
-struct CBlockLocator
-{
-    std::vector<uint256> vHave;
-
-    CBlockLocator() {}
-
-    CBlockLocator(const std::vector<uint256>& vHaveIn)
-    {
-        vHave = vHaveIn;
-    }
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        if (!(nType & SER_GETHASH))
-            READWRITE(nVersion);
-        READWRITE(vHave);
-    }
-
-    void SetNull()
-    {
-        vHave.clear();
-    }
-
-    bool IsNull()
-    {
-        return vHave.empty();
-    }
-};
-
-#endif // BITCOIN_CORE_H
diff --git a/src/core/block.cpp b/src/core/block.cpp
new file mode 100644
index 0000000000..2010d44dac
--- /dev/null
+++ b/src/core/block.cpp
@@ -0,0 +1,130 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "core/block.h"
+
+#include "hash.h"
+#include "tinyformat.h"
+#include "utilstrencodings.h"
+
+uint256 CBlockHeader::GetHash() const
+{
+    return Hash(BEGIN(nVersion), END(nNonce));
+}
+
+uint256 CBlock::BuildMerkleTree(bool* fMutated) const
+{
+    /* WARNING! If you're reading this because you're learning about crypto
+       and/or designing a new system that will use merkle trees, keep in mind
+       that the following merkle tree algorithm has a serious flaw related to
+       duplicate txids, resulting in a vulnerability (CVE-2012-2459).
+
+       The reason is that if the number of hashes in the list at a given time
+       is odd, the last one is duplicated before computing the next level (which
+       is unusual in Merkle trees). This results in certain sequences of
+       transactions leading to the same merkle root. For example, these two
+       trees:
+
+                    A               A
+                  /  \            /   \
+                B     C         B       C
+               / \    |        / \     / \
+              D   E   F       D   E   F   F
+             / \ / \ / \     / \ / \ / \ / \
+             1 2 3 4 5 6     1 2 3 4 5 6 5 6
+
+       for transaction lists [1,2,3,4,5,6] and [1,2,3,4,5,6,5,6] (where 5 and
+       6 are repeated) result in the same root hash A (because the hash of both
+       of (F) and (F,F) is C).
+
+       The vulnerability results from being able to send a block with such a
+       transaction list, with the same merkle root, and the same block hash as
+       the original without duplication, resulting in failed validation. If the
+       receiving node proceeds to mark that block as permanently invalid
+       however, it will fail to accept further unmodified (and thus potentially
+       valid) versions of the same block. We defend against this by detecting
+       the case where we would hash two identical hashes at the end of the list
+       together, and treating that identically to the block having an invalid
+       merkle root. Assuming no double-SHA256 collisions, this will detect all
+       known ways of changing the transactions without affecting the merkle
+       root.
+    */
+    vMerkleTree.clear();
+    vMerkleTree.reserve(vtx.size() * 2 + 16); // Safe upper bound for the number of total nodes.
+    for (std::vector<CTransaction>::const_iterator it(vtx.begin()); it != vtx.end(); ++it)
+        vMerkleTree.push_back(it->GetHash());
+    int j = 0;
+    bool mutated = false;
+    for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
+    {
+        for (int i = 0; i < nSize; i += 2)
+        {
+            int i2 = std::min(i+1, nSize-1);
+            if (i2 == i + 1 && i2 + 1 == nSize && vMerkleTree[j+i] == vMerkleTree[j+i2]) {
+                // Two identical hashes at the end of the list at a particular level.
+                mutated = true;
+            }
+            vMerkleTree.push_back(Hash(BEGIN(vMerkleTree[j+i]),  END(vMerkleTree[j+i]),
+                                       BEGIN(vMerkleTree[j+i2]), END(vMerkleTree[j+i2])));
+        }
+        j += nSize;
+    }
+    if (fMutated) {
+        *fMutated = mutated;
+    }
+    return (vMerkleTree.empty() ? 0 : vMerkleTree.back());
+}
+
+std::vector<uint256> CBlock::GetMerkleBranch(int nIndex) const
+{
+    if (vMerkleTree.empty())
+        BuildMerkleTree();
+    std::vector<uint256> vMerkleBranch;
+    int j = 0;
+    for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
+    {
+        int i = std::min(nIndex^1, nSize-1);
+        vMerkleBranch.push_back(vMerkleTree[j+i]);
+        nIndex >>= 1;
+        j += nSize;
+    }
+    return vMerkleBranch;
+}
+
+uint256 CBlock::CheckMerkleBranch(uint256 hash, const std::vector<uint256>& vMerkleBranch, int nIndex)
+{
+    if (nIndex == -1)
+        return 0;
+    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;
+}
+
+std::string CBlock::ToString() const
+{
+    std::stringstream s;
+    s << strprintf("CBlock(hash=%s, ver=%d, hashPrevBlock=%s, hashMerkleRoot=%s, nTime=%u, nBits=%08x, nNonce=%u, vtx=%u)\n",
+        GetHash().ToString(),
+        nVersion,
+        hashPrevBlock.ToString(),
+        hashMerkleRoot.ToString(),
+        nTime, nBits, nNonce,
+        vtx.size());
+    for (unsigned int i = 0; i < vtx.size(); i++)
+    {
+        s << "  " << vtx[i].ToString() << "\n";
+    }
+    s << "  vMerkleTree: ";
+    for (unsigned int i = 0; i < vMerkleTree.size(); i++)
+        s << " " << vMerkleTree[i].ToString();
+    s << "\n";
+    return s.str();
+}
diff --git a/src/core/block.h b/src/core/block.h
new file mode 100644
index 0000000000..f1eb7a844f
--- /dev/null
+++ b/src/core/block.h
@@ -0,0 +1,168 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef H_BITCOIN_CORE_BLOCK
+#define H_BITCOIN_CORE_BLOCK
+
+#include "core/transaction.h"
+#include "serialize.h"
+#include "uint256.h"
+
+/** Nodes collect new transactions into a block, hash them into a hash tree,
+ * and scan through nonce values to make the block's hash satisfy proof-of-work
+ * requirements.  When they solve the proof-of-work, they broadcast the block
+ * to everyone and the block is added to the block chain.  The first transaction
+ * in the block is a special one that creates a new coin owned by the creator
+ * of the block.
+ */
+class CBlockHeader
+{
+public:
+    // header
+    static const int32_t CURRENT_VERSION=2;
+    int32_t nVersion;
+    uint256 hashPrevBlock;
+    uint256 hashMerkleRoot;
+    uint32_t nTime;
+    uint32_t nBits;
+    uint32_t nNonce;
+
+    CBlockHeader()
+    {
+        SetNull();
+    }
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(this->nVersion);
+        nVersion = this->nVersion;
+        READWRITE(hashPrevBlock);
+        READWRITE(hashMerkleRoot);
+        READWRITE(nTime);
+        READWRITE(nBits);
+        READWRITE(nNonce);
+    }
+
+    void SetNull()
+    {
+        nVersion = CBlockHeader::CURRENT_VERSION;
+        hashPrevBlock = 0;
+        hashMerkleRoot = 0;
+        nTime = 0;
+        nBits = 0;
+        nNonce = 0;
+    }
+
+    bool IsNull() const
+    {
+        return (nBits == 0);
+    }
+
+    uint256 GetHash() const;
+
+    int64_t GetBlockTime() const
+    {
+        return (int64_t)nTime;
+    }
+};
+
+
+class CBlock : public CBlockHeader
+{
+public:
+    // network and disk
+    std::vector<CTransaction> vtx;
+
+    // memory only
+    mutable std::vector<uint256> vMerkleTree;
+
+    CBlock()
+    {
+        SetNull();
+    }
+
+    CBlock(const CBlockHeader &header)
+    {
+        SetNull();
+        *((CBlockHeader*)this) = header;
+    }
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(*(CBlockHeader*)this);
+        READWRITE(vtx);
+    }
+
+    void SetNull()
+    {
+        CBlockHeader::SetNull();
+        vtx.clear();
+        vMerkleTree.clear();
+    }
+
+    CBlockHeader GetBlockHeader() const
+    {
+        CBlockHeader block;
+        block.nVersion       = nVersion;
+        block.hashPrevBlock  = hashPrevBlock;
+        block.hashMerkleRoot = hashMerkleRoot;
+        block.nTime          = nTime;
+        block.nBits          = nBits;
+        block.nNonce         = nNonce;
+        return block;
+    }
+
+    // Build the in-memory merkle tree for this block and return the merkle root.
+    // If non-NULL, *mutated is set to whether mutation was detected in the merkle
+    // tree (a duplication of transactions in the block leading to an identical
+    // merkle root).
+    uint256 BuildMerkleTree(bool* mutated = NULL) const;
+
+    std::vector<uint256> GetMerkleBranch(int nIndex) const;
+    static uint256 CheckMerkleBranch(uint256 hash, const std::vector<uint256>& vMerkleBranch, int nIndex);
+    std::string ToString() const;
+};
+
+
+/** Describes a place in the block chain to another node such that if the
+ * other node doesn't have the same branch, it can find a recent common trunk.
+ * The further back it is, the further before the fork it may be.
+ */
+struct CBlockLocator
+{
+    std::vector<uint256> vHave;
+
+    CBlockLocator() {}
+
+    CBlockLocator(const std::vector<uint256>& vHaveIn)
+    {
+        vHave = vHaveIn;
+    }
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        if (!(nType & SER_GETHASH))
+            READWRITE(nVersion);
+        READWRITE(vHave);
+    }
+
+    void SetNull()
+    {
+        vHave.clear();
+    }
+
+    bool IsNull()
+    {
+        return vHave.empty();
+    }
+};
+
+#endif // H_BITCOIN_CORE_BLOCK
diff --git a/src/core/transaction.cpp b/src/core/transaction.cpp
new file mode 100644
index 0000000000..f835bafb9f
--- /dev/null
+++ b/src/core/transaction.cpp
@@ -0,0 +1,142 @@
+// 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 "core/transaction.h"
+
+#include "hash.h"
+#include "tinyformat.h"
+#include "utilstrencodings.h"
+
+std::string COutPoint::ToString() const
+{
+    return strprintf("COutPoint(%s, %u)", hash.ToString().substr(0,10), n);
+}
+
+CTxIn::CTxIn(COutPoint prevoutIn, CScript scriptSigIn, uint32_t nSequenceIn)
+{
+    prevout = prevoutIn;
+    scriptSig = scriptSigIn;
+    nSequence = nSequenceIn;
+}
+
+CTxIn::CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn, uint32_t nSequenceIn)
+{
+    prevout = COutPoint(hashPrevTx, nOut);
+    scriptSig = scriptSigIn;
+    nSequence = nSequenceIn;
+}
+
+std::string CTxIn::ToString() const
+{
+    std::string str;
+    str += "CTxIn(";
+    str += prevout.ToString();
+    if (prevout.IsNull())
+        str += strprintf(", coinbase %s", HexStr(scriptSig));
+    else
+        str += strprintf(", scriptSig=%s", scriptSig.ToString().substr(0,24));
+    if (nSequence != std::numeric_limits<unsigned int>::max())
+        str += strprintf(", nSequence=%u", nSequence);
+    str += ")";
+    return str;
+}
+
+CTxOut::CTxOut(const CAmount& nValueIn, CScript scriptPubKeyIn)
+{
+    nValue = nValueIn;
+    scriptPubKey = scriptPubKeyIn;
+}
+
+uint256 CTxOut::GetHash() const
+{
+    return SerializeHash(*this);
+}
+
+std::string CTxOut::ToString() const
+{
+    return strprintf("CTxOut(nValue=%d.%08d, scriptPubKey=%s)", nValue / COIN, nValue % COIN, scriptPubKey.ToString().substr(0,30));
+}
+
+CMutableTransaction::CMutableTransaction() : nVersion(CTransaction::CURRENT_VERSION), nLockTime(0) {}
+CMutableTransaction::CMutableTransaction(const CTransaction& tx) : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout), nLockTime(tx.nLockTime) {}
+
+uint256 CMutableTransaction::GetHash() const
+{
+    return SerializeHash(*this);
+}
+
+void CTransaction::UpdateHash() const
+{
+    *const_cast<uint256*>(&hash) = SerializeHash(*this);
+}
+
+CTransaction::CTransaction() : hash(0), nVersion(CTransaction::CURRENT_VERSION), vin(), vout(), nLockTime(0) { }
+
+CTransaction::CTransaction(const CMutableTransaction &tx) : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout), nLockTime(tx.nLockTime) {
+    UpdateHash();
+}
+
+CTransaction& CTransaction::operator=(const CTransaction &tx) {
+    *const_cast<int*>(&nVersion) = tx.nVersion;
+    *const_cast<std::vector<CTxIn>*>(&vin) = tx.vin;
+    *const_cast<std::vector<CTxOut>*>(&vout) = tx.vout;
+    *const_cast<unsigned int*>(&nLockTime) = tx.nLockTime;
+    *const_cast<uint256*>(&hash) = tx.hash;
+    return *this;
+}
+
+CAmount CTransaction::GetValueOut() const
+{
+    CAmount nValueOut = 0;
+    for (std::vector<CTxOut>::const_iterator it(vout.begin()); it != vout.end(); ++it)
+    {
+        nValueOut += it->nValue;
+        if (!MoneyRange(it->nValue) || !MoneyRange(nValueOut))
+            throw std::runtime_error("CTransaction::GetValueOut() : value out of range");
+    }
+    return nValueOut;
+}
+
+double CTransaction::ComputePriority(double dPriorityInputs, unsigned int nTxSize) const
+{
+    nTxSize = CalculateModifiedSize(nTxSize);
+    if (nTxSize == 0) return 0.0;
+
+    return dPriorityInputs / nTxSize;
+}
+
+unsigned int CTransaction::CalculateModifiedSize(unsigned int nTxSize) const
+{
+    // In order to avoid disincentivizing cleaning up the UTXO set we don't count
+    // the constant overhead for each txin and up to 110 bytes of scriptSig (which
+    // is enough to cover a compressed pubkey p2sh redemption) for priority.
+    // Providing any more cleanup incentive than making additional inputs free would
+    // risk encouraging people to create junk outputs to redeem later.
+    if (nTxSize == 0)
+        nTxSize = ::GetSerializeSize(*this, SER_NETWORK, PROTOCOL_VERSION);
+    for (std::vector<CTxIn>::const_iterator it(vin.begin()); it != vin.end(); ++it)
+    {
+        unsigned int offset = 41U + std::min(110U, (unsigned int)it->scriptSig.size());
+        if (nTxSize > offset)
+            nTxSize -= offset;
+    }
+    return nTxSize;
+}
+
+std::string CTransaction::ToString() const
+{
+    std::string str;
+    str += strprintf("CTransaction(hash=%s, ver=%d, vin.size=%u, vout.size=%u, nLockTime=%u)\n",
+        GetHash().ToString().substr(0,10),
+        nVersion,
+        vin.size(),
+        vout.size(),
+        nLockTime);
+    for (unsigned int i = 0; i < vin.size(); i++)
+        str += "    " + vin[i].ToString() + "\n";
+    for (unsigned int i = 0; i < vout.size(); i++)
+        str += "    " + vout[i].ToString() + "\n";
+    return str;
+}
diff --git a/src/core/transaction.h b/src/core/transaction.h
new file mode 100644
index 0000000000..c21558cfeb
--- /dev/null
+++ b/src/core/transaction.h
@@ -0,0 +1,276 @@
+// 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 H_BITCOIN_CORE_TRANSACTION
+#define H_BITCOIN_CORE_TRANSACTION
+
+#include "amount.h"
+#include "script/script.h"
+#include "serialize.h"
+#include "uint256.h"
+
+/** An outpoint - a combination of a transaction hash and an index n into its vout */
+class COutPoint
+{
+public:
+    uint256 hash;
+    uint32_t n;
+
+    COutPoint() { SetNull(); }
+    COutPoint(uint256 hashIn, uint32_t nIn) { hash = hashIn; n = nIn; }
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(FLATDATA(*this));
+    }
+
+    void SetNull() { hash = 0; n = (uint32_t) -1; }
+    bool IsNull() const { return (hash == 0 && n == (uint32_t) -1); }
+
+    friend bool operator<(const COutPoint& a, const COutPoint& b)
+    {
+        return (a.hash < b.hash || (a.hash == b.hash && a.n < b.n));
+    }
+
+    friend bool operator==(const COutPoint& a, const COutPoint& b)
+    {
+        return (a.hash == b.hash && a.n == b.n);
+    }
+
+    friend bool operator!=(const COutPoint& a, const COutPoint& b)
+    {
+        return !(a == b);
+    }
+
+    std::string ToString() const;
+};
+
+/** An input of a transaction.  It contains the location of the previous
+ * transaction's output that it claims and a signature that matches the
+ * output's public key.
+ */
+class CTxIn
+{
+public:
+    COutPoint prevout;
+    CScript scriptSig;
+    uint32_t nSequence;
+
+    CTxIn()
+    {
+        nSequence = std::numeric_limits<unsigned int>::max();
+    }
+
+    explicit CTxIn(COutPoint prevoutIn, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=std::numeric_limits<unsigned int>::max());
+    CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=std::numeric_limits<uint32_t>::max());
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(prevout);
+        READWRITE(scriptSig);
+        READWRITE(nSequence);
+    }
+
+    bool IsFinal() const
+    {
+        return (nSequence == std::numeric_limits<uint32_t>::max());
+    }
+
+    friend bool operator==(const CTxIn& a, const CTxIn& b)
+    {
+        return (a.prevout   == b.prevout &&
+                a.scriptSig == b.scriptSig &&
+                a.nSequence == b.nSequence);
+    }
+
+    friend bool operator!=(const CTxIn& a, const CTxIn& b)
+    {
+        return !(a == b);
+    }
+
+    std::string ToString() const;
+};
+
+/** An output of a transaction.  It contains the public key that the next input
+ * must be able to sign with to claim it.
+ */
+class CTxOut
+{
+public:
+    CAmount nValue;
+    CScript scriptPubKey;
+
+    CTxOut()
+    {
+        SetNull();
+    }
+
+    CTxOut(const CAmount& nValueIn, CScript scriptPubKeyIn);
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(nValue);
+        READWRITE(scriptPubKey);
+    }
+
+    void SetNull()
+    {
+        nValue = -1;
+        scriptPubKey.clear();
+    }
+
+    bool IsNull() const
+    {
+        return (nValue == -1);
+    }
+
+    uint256 GetHash() const;
+
+    bool IsDust(CFeeRate minRelayTxFee) const
+    {
+        // "Dust" is defined in terms of CTransaction::minRelayTxFee,
+        // which has units satoshis-per-kilobyte.
+        // If you'd pay more than 1/3 in fees
+        // to spend something, then we consider it dust.
+        // A typical txout is 34 bytes big, and will
+        // need a CTxIn of at least 148 bytes to spend:
+        // so dust is a txout less than 546 satoshis 
+        // with default minRelayTxFee.
+        size_t nSize = GetSerializeSize(SER_DISK,0)+148u;
+        return (nValue < 3*minRelayTxFee.GetFee(nSize));
+    }
+
+    friend bool operator==(const CTxOut& a, const CTxOut& b)
+    {
+        return (a.nValue       == b.nValue &&
+                a.scriptPubKey == b.scriptPubKey);
+    }
+
+    friend bool operator!=(const CTxOut& a, const CTxOut& b)
+    {
+        return !(a == b);
+    }
+
+    std::string ToString() const;
+};
+
+struct CMutableTransaction;
+
+/** The basic transaction that is broadcasted on the network and contained in
+ * blocks.  A transaction can contain multiple inputs and outputs.
+ */
+class CTransaction
+{
+private:
+    /** Memory only. */
+    const uint256 hash;
+    void UpdateHash() const;
+
+public:
+    static const int32_t CURRENT_VERSION=1;
+
+    // The local variables are made const to prevent unintended modification
+    // without updating the cached hash value. However, CTransaction is not
+    // actually immutable; deserialization and assignment are implemented,
+    // and bypass the constness. This is safe, as they update the entire
+    // structure, including the hash.
+    const int32_t nVersion;
+    const std::vector<CTxIn> vin;
+    const std::vector<CTxOut> vout;
+    const uint32_t nLockTime;
+
+    /** Construct a CTransaction that qualifies as IsNull() */
+    CTransaction();
+
+    /** Convert a CMutableTransaction into a CTransaction. */
+    CTransaction(const CMutableTransaction &tx);
+
+    CTransaction& operator=(const CTransaction& tx);
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(*const_cast<int32_t*>(&this->nVersion));
+        nVersion = this->nVersion;
+        READWRITE(*const_cast<std::vector<CTxIn>*>(&vin));
+        READWRITE(*const_cast<std::vector<CTxOut>*>(&vout));
+        READWRITE(*const_cast<uint32_t*>(&nLockTime));
+        if (ser_action.ForRead())
+            UpdateHash();
+    }
+
+    bool IsNull() const {
+        return vin.empty() && vout.empty();
+    }
+
+    const uint256& GetHash() const {
+        return hash;
+    }
+
+    // Return sum of txouts.
+    CAmount GetValueOut() const;
+    // GetValueIn() is a method on CCoinsViewCache, because
+    // inputs must be known to compute value in.
+
+    // Compute priority, given priority of inputs and (optionally) tx size
+    double ComputePriority(double dPriorityInputs, unsigned int nTxSize=0) const;
+
+    // Compute modified tx size for priority calculation (optionally given tx size)
+    unsigned int CalculateModifiedSize(unsigned int nTxSize=0) const;
+
+    bool IsCoinBase() const
+    {
+        return (vin.size() == 1 && vin[0].prevout.IsNull());
+    }
+
+    friend bool operator==(const CTransaction& a, const CTransaction& b)
+    {
+        return a.hash == b.hash;
+    }
+
+    friend bool operator!=(const CTransaction& a, const CTransaction& b)
+    {
+        return a.hash != b.hash;
+    }
+
+    std::string ToString() const;
+};
+
+/** A mutable version of CTransaction. */
+struct CMutableTransaction
+{
+    int32_t nVersion;
+    std::vector<CTxIn> vin;
+    std::vector<CTxOut> vout;
+    uint32_t nLockTime;
+
+    CMutableTransaction();
+    CMutableTransaction(const CTransaction& tx);
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(this->nVersion);
+        nVersion = this->nVersion;
+        READWRITE(vin);
+        READWRITE(vout);
+        READWRITE(nLockTime);
+    }
+
+    /** Compute the hash of this CMutableTransaction. This is computed on the
+     * fly, as opposed to GetHash() in CTransaction, which uses a cached result.
+     */
+    uint256 GetHash() const;
+};
+
+#endif // H_BITCOIN_CORE_TRANSACTION
diff --git a/src/core_read.cpp b/src/core_read.cpp
index dcbcf4b4f7..d39bc9a780 100644
--- a/src/core_read.cpp
+++ b/src/core_read.cpp
@@ -4,7 +4,7 @@
 
 #include "core_io.h"
 
-#include "core.h"
+#include "core/transaction.h"
 #include "script/script.h"
 #include "serialize.h"
 #include "streams.h"
diff --git a/src/core_write.cpp b/src/core_write.cpp
index b2b29fb367..a3ae8eec07 100644
--- a/src/core_write.cpp
+++ b/src/core_write.cpp
@@ -5,7 +5,7 @@
 #include "core_io.h"
 
 #include "base58.h"
-#include "core.h"
+#include "core/transaction.h"
 #include "script/script.h"
 #include "script/standard.h"
 #include "serialize.h"
diff --git a/src/init.cpp b/src/init.cpp
index 70ac5190d3..d928094bba 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -10,6 +10,7 @@
 #include "init.h"
 
 #include "addrman.h"
+#include "amount.h"
 #include "checkpoints.h"
 #include "compat/sanity.h"
 #include "key.h"
diff --git a/src/main.h b/src/main.h
index 1ef51918c5..1941ca7059 100644
--- a/src/main.h
+++ b/src/main.h
@@ -10,10 +10,12 @@
 #include "config/bitcoin-config.h"
 #endif
 
+#include "amount.h"
 #include "chain.h"
 #include "chainparams.h"
 #include "coins.h"
-#include "core.h"
+#include "core/block.h"
+#include "core/transaction.h"
 #include "net.h"
 #include "pow.h"
 #include "script/script.h"
@@ -23,6 +25,7 @@
 #include "tinyformat.h"
 #include "txmempool.h"
 #include "uint256.h"
+#include "undo.h"
 
 #include <algorithm>
 #include <exception>
@@ -127,7 +130,6 @@ static const uint64_t nMinDiskSpace = 52428800;
 
 
 class CBlockTreeDB;
-class CTxUndo;
 class CScriptCheck;
 class CValidationState;
 class CValidationInterface;
diff --git a/src/miner.cpp b/src/miner.cpp
index eefccfd641..0235de3ab3 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -5,7 +5,9 @@
 
 #include "miner.h"
 
-#include "core.h"
+#include "amount.h"
+#include "core/block.h"
+#include "core/transaction.h"
 #include "hash.h"
 #include "main.h"
 #include "net.h"
diff --git a/src/net.cpp b/src/net.cpp
index 6cf64f51c3..6cccdca952 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -11,7 +11,7 @@
 
 #include "addrman.h"
 #include "chainparams.h"
-#include "core.h"
+#include "core/transaction.h"
 #include "ui_interface.h"
 
 #ifdef WIN32
diff --git a/src/pow.cpp b/src/pow.cpp
index 75fbfc6a6d..af7fc488ef 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -6,7 +6,7 @@
 #include "pow.h"
 
 #include "chainparams.h"
-#include "core.h"
+#include "core/block.h"
 #include "main.h"
 #include "timedata.h"
 #include "uint256.h"
diff --git a/src/qt/bitcoinunits.cpp b/src/qt/bitcoinunits.cpp
index 423b559bf7..c85f569fd3 100644
--- a/src/qt/bitcoinunits.cpp
+++ b/src/qt/bitcoinunits.cpp
@@ -4,7 +4,7 @@
 
 #include "bitcoinunits.h"
 
-#include "core.h"
+#include "core/transaction.h"
 
 #include <QStringList>
 
diff --git a/src/qt/guiutil.cpp b/src/qt/guiutil.cpp
index 91bb10755a..22a1f019e9 100644
--- a/src/qt/guiutil.cpp
+++ b/src/qt/guiutil.cpp
@@ -9,7 +9,7 @@
 #include "qvalidatedlineedit.h"
 #include "walletmodel.h"
 
-#include "core.h"
+#include "core/transaction.h"
 #include "init.h"
 #include "main.h"
 #include "protocol.h"
diff --git a/src/qt/optionsmodel.cpp b/src/qt/optionsmodel.cpp
index 6db654dff7..c941ebd4ca 100644
--- a/src/qt/optionsmodel.cpp
+++ b/src/qt/optionsmodel.cpp
@@ -11,6 +11,7 @@
 #include "bitcoinunits.h"
 #include "guiutil.h"
 
+#include "amount.h"
 #include "init.h"
 #include "main.h"
 #include "net.h"
diff --git a/src/rpcmining.cpp b/src/rpcmining.cpp
index c767835a27..8af3c46348 100644
--- a/src/rpcmining.cpp
+++ b/src/rpcmining.cpp
@@ -3,6 +3,7 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include "amount.h"
 #include "chainparams.h"
 #include "core_io.h"
 #include "init.h"
diff --git a/src/rpcrawtransaction.cpp b/src/rpcrawtransaction.cpp
index fdfcb59eeb..d3ce3b3191 100644
--- a/src/rpcrawtransaction.cpp
+++ b/src/rpcrawtransaction.cpp
@@ -4,7 +4,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "base58.h"
-#include "core.h"
+#include "core/transaction.h"
 #include "core_io.h"
 #include "init.h"
 #include "keystore.h"
diff --git a/src/rpcwallet.cpp b/src/rpcwallet.cpp
index 68bb4068b8..2728fb4fb3 100644
--- a/src/rpcwallet.cpp
+++ b/src/rpcwallet.cpp
@@ -3,6 +3,7 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include "amount.h"
 #include "base58.h"
 #include "core_io.h"
 #include "rpcserver.h"
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 11c909472a..3625972ebf 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -5,7 +5,7 @@
 
 #include "interpreter.h"
 
-#include "core.h"
+#include "core/transaction.h"
 #include "crypto/ripemd160.h"
 #include "crypto/sha1.h"
 #include "crypto/sha2.h"
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index bf98c40394..0eab0626e5 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -5,7 +5,7 @@
 
 #include "script/sign.h"
 
-#include "core.h"
+#include "core/transaction.h"
 #include "key.h"
 #include "keystore.h"
 #include "script/standard.h"
diff --git a/src/test/compress_tests.cpp b/src/test/compress_tests.cpp
index 719955ba85..bf404cf0cf 100644
--- a/src/test/compress_tests.cpp
+++ b/src/test/compress_tests.cpp
@@ -2,7 +2,7 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include "main.h"
+#include "compressor.h"
 #include "util.h"
 
 #include <stdint.h>
diff --git a/src/test/main_tests.cpp b/src/test/main_tests.cpp
index 70a800af51..78c4181409 100644
--- a/src/test/main_tests.cpp
+++ b/src/test/main_tests.cpp
@@ -2,7 +2,7 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include "core.h"
+#include "core/transaction.h"
 #include "main.h"
 
 #include <boost/test/unit_test.hpp>
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 61daa0a3fe..761210feac 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -4,7 +4,7 @@
 
 #include "util.h"
 
-#include "core.h"
+#include "core/transaction.h"
 #include "random.h"
 #include "sync.h"
 #include "utilstrencodings.h"
diff --git a/src/txdb.cpp b/src/txdb.cpp
index 8a73ce961c..0731d843f3 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -5,7 +5,6 @@
 
 #include "txdb.h"
 
-#include "core.h"
 #include "pow.h"
 #include "uint256.h"
 
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index b0d6b4aefa..c042dd8467 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -5,7 +5,6 @@
 
 #include "txmempool.h"
 
-#include "core.h"
 #include "streams.h"
 #include "util.h"
 #include "utilmoneystr.h"
diff --git a/src/txmempool.h b/src/txmempool.h
index 85cf5310ff..2ec80cb860 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -8,8 +8,9 @@
 
 #include <list>
 
+#include "amount.h"
 #include "coins.h"
-#include "core.h"
+#include "core/transaction.h"
 #include "sync.h"
 
 class CAutoFile;
diff --git a/src/undo.h b/src/undo.h
new file mode 100644
index 0000000000..232c193429
--- /dev/null
+++ b/src/undo.h
@@ -0,0 +1,71 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef H_BITCOIN_TXUNDO
+#define H_BITCOIN_TXUNDO
+
+#include "compressor.h" 
+#include "core/transaction.h"
+#include "serialize.h"
+
+/** Undo information for a CTxIn
+ *
+ *  Contains the prevout's CTxOut being spent, and if this was the
+ *  last output of the affected transaction, its metadata as well
+ *  (coinbase or not, height, transaction version)
+ */
+class CTxInUndo
+{
+public:
+    CTxOut txout;         // the txout data before being spent
+    bool fCoinBase;       // if the outpoint was the last unspent: whether it belonged to a coinbase
+    unsigned int nHeight; // if the outpoint was the last unspent: its height
+    int nVersion;         // if the outpoint was the last unspent: its version
+
+    CTxInUndo() : txout(), fCoinBase(false), nHeight(0), nVersion(0) {}
+    CTxInUndo(const CTxOut &txoutIn, bool fCoinBaseIn = false, unsigned int nHeightIn = 0, int nVersionIn = 0) : txout(txoutIn), fCoinBase(fCoinBaseIn), nHeight(nHeightIn), nVersion(nVersionIn) { }
+
+    unsigned int GetSerializeSize(int nType, int nVersion) const {
+        return ::GetSerializeSize(VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion) +
+               (nHeight > 0 ? ::GetSerializeSize(VARINT(this->nVersion), nType, nVersion) : 0) +
+               ::GetSerializeSize(CTxOutCompressor(REF(txout)), nType, nVersion);
+    }
+
+    template<typename Stream>
+    void Serialize(Stream &s, int nType, int nVersion) const {
+        ::Serialize(s, VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion);
+        if (nHeight > 0)
+            ::Serialize(s, VARINT(this->nVersion), nType, nVersion);
+        ::Serialize(s, CTxOutCompressor(REF(txout)), nType, nVersion);
+    }
+
+    template<typename Stream>
+    void Unserialize(Stream &s, int nType, int nVersion) {
+        unsigned int nCode = 0;
+        ::Unserialize(s, VARINT(nCode), nType, nVersion);
+        nHeight = nCode / 2;
+        fCoinBase = nCode & 1;
+        if (nHeight > 0)
+            ::Unserialize(s, VARINT(this->nVersion), nType, nVersion);
+        ::Unserialize(s, REF(CTxOutCompressor(REF(txout))), nType, nVersion);
+    }
+};
+
+/** Undo information for a CTransaction */
+class CTxUndo
+{
+public:
+    // undo information for all txins
+    std::vector<CTxInUndo> vprevout;
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(vprevout);
+    }
+};
+
+#endif // H_BITCOIN_TXUNDO
diff --git a/src/utilmoneystr.cpp b/src/utilmoneystr.cpp
index 95be06aa18..267a5b845c 100644
--- a/src/utilmoneystr.cpp
+++ b/src/utilmoneystr.cpp
@@ -5,7 +5,7 @@
 
 #include "utilmoneystr.h"
 
-#include "core.h"
+#include "core/transaction.h"
 #include "tinyformat.h"
 #include "utilstrencodings.h"
 
diff --git a/src/wallet.h b/src/wallet.h
index 9b6895090c..768887e0cb 100644
--- a/src/wallet.h
+++ b/src/wallet.h
@@ -6,7 +6,9 @@
 #ifndef BITCOIN_WALLET_H
 #define BITCOIN_WALLET_H
 
-#include "core.h"
+#include "amount.h"
+#include "core/block.h"
+#include "core/transaction.h"
 #include "crypter.h"
 #include "key.h"
 #include "keystore.h"