6 files changed, 23 insertions, 13 deletions
diff --git a/src/script/bitcoinconsensus.cpp b/src/script/bitcoinconsensus.cpp
index c8dd54a747..b0d5faaf77 100644
--- a/src/script/bitcoinconsensus.cpp
+++ b/src/script/bitcoinconsensus.cpp
@@ -78,7 +78,7 @@ int bitcoinconsensus_verify_script(const unsigned char *scriptPubKey, unsigned i
          // Regardless of the verification result, the tx did not error.
          set_error(err, bitcoinconsensus_ERR_OK);
 
-        return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, SignatureChecker(tx, nIn), NULL);
+        return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, TransactionSignatureChecker(&tx, nIn), NULL);
     } catch (const std::exception&) {
         return set_error(err, bitcoinconsensus_ERR_TX_DESERIALIZE); // Error deserializing
     }
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 0cee1a0116..af7c641c05 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -1058,12 +1058,12 @@ uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsig
     return ss.GetHash();
 }
 
-bool SignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
+bool TransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
 {
     return pubkey.Verify(sighash, vchSig);
 }
 
-bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
+bool TransactionSignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
 {
     CPubKey pubkey(vchPubKey);
     if (!pubkey.IsValid())
@@ -1076,7 +1076,7 @@ bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vec
     int nHashType = vchSig.back();
     vchSig.pop_back();
 
-    uint256 sighash = SignatureHash(scriptCode, txTo, nIn, nHashType);
+    uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType);
 
     if (!VerifySignature(vchSig, pubkey, sighash))
         return false;
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index 8bf379ed89..fc64438f68 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -7,6 +7,7 @@
 #define BITCOIN_SCRIPT_INTERPRETER_H
 
 #include "script_error.h"
+#include "primitives/transaction.h"
 
 #include <vector>
 #include <stdint.h>
@@ -90,20 +91,29 @@ public:
     virtual ~BaseSignatureChecker() {}
 };
 
-class SignatureChecker : public BaseSignatureChecker
+class TransactionSignatureChecker : public BaseSignatureChecker
 {
 private:
-    const CTransaction& txTo;
+    const CTransaction* txTo;
     unsigned int nIn;
 
 protected:
     virtual bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
 
 public:
-    SignatureChecker(const CTransaction& txToIn, unsigned int nInIn) : txTo(txToIn), nIn(nInIn) {}
+    TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn) : txTo(txToIn), nIn(nInIn) {}
     bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode) const;
 };
 
+class MutableTransactionSignatureChecker : public TransactionSignatureChecker
+{
+private:
+    const CTransaction txTo;
+
+public:
+    MutableTransactionSignatureChecker(const CMutableTransaction* txToIn, unsigned int nInIn) : TransactionSignatureChecker(&txTo, nInIn), txTo(*txToIn) {}
+};
+
 bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* error = NULL);
 bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* error = NULL);
 
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp
index 75ecdb563d..099b4ad0e3 100644
--- a/src/script/sigcache.cpp
+++ b/src/script/sigcache.cpp
@@ -74,14 +74,14 @@ public:
 
 }
 
-bool CachingSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
+bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
 {
     static CSignatureCache signatureCache;
 
     if (signatureCache.Get(sighash, vchSig, pubkey))
         return true;
 
-    if (!SignatureChecker::VerifySignature(vchSig, pubkey, sighash))
+    if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash))
         return false;
 
     if (store)
diff --git a/src/script/sigcache.h b/src/script/sigcache.h
index 3bd11caff5..b299038daa 100644
--- a/src/script/sigcache.h
+++ b/src/script/sigcache.h
@@ -12,13 +12,13 @@
 
 class CPubKey;
 
-class CachingSignatureChecker : public SignatureChecker
+class CachingTransactionSignatureChecker : public TransactionSignatureChecker
 {
 private:
     bool store;
 
 public:
-    CachingSignatureChecker(const CTransaction& txToIn, unsigned int nInIn, bool storeIn=true) : SignatureChecker(txToIn, nInIn), store(storeIn) {}
+    CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, bool storeIn=true) : TransactionSignatureChecker(txToIn, nInIn), store(storeIn) {}
 
     bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
 };
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index adddd4ec78..14119f7e2c 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -123,7 +123,7 @@ bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CMutabl
     }
 
     // Test solution
-    return VerifyScript(txin.scriptSig, fromPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, SignatureChecker(txTo, nIn));
+    return VerifyScript(txin.scriptSig, fromPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, MutableTransactionSignatureChecker(&txTo, nIn));
 }
 
 bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
@@ -174,7 +174,7 @@ static CScript CombineMultisig(const CScript& scriptPubKey, const CTransaction&
             if (sigs.count(pubkey))
                 continue; // Already got a sig for this pubkey
 
-            if (SignatureChecker(txTo, nIn).CheckSig(sig, pubkey, scriptPubKey))
+            if (TransactionSignatureChecker(&txTo, nIn).CheckSig(sig, pubkey, scriptPubKey))
             {
                 sigs[pubkey] = sig;
                 break;