From 5a1c7d5acc088df01c6f43e977b6b7d0704b4841 Mon Sep 17 00:00:00 2001
From: timemarkovqtum <time.markov@qtum.com>
Date: Tue, 4 Jun 2024 12:11:17 +0200
Subject: [PATCH] Port script

---
 src/script/descriptor.cpp  |   1 +
 src/script/interpreter.cpp | 180 ++++++++++++++++++++++++++++++++++---
 src/script/interpreter.h   |  41 ++++++++-
 src/script/sigcache.cpp    |  13 +++
 src/script/sigcache.h      |  11 +++
 src/script/sign.cpp        | 138 ++++++++++++++++++++++++++++
 src/script/sign.h          |  30 +++++++
 src/script/solver.cpp      |  73 ++++++++++++++-
 src/script/solver.h        |  18 +++-
 9 files changed, 491 insertions(+), 14 deletions(-)

diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index c6bc5f8f1d..2b662d7afe 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -783,6 +783,7 @@ class PKDescriptor final : public DescriptorImpl
     }
 public:
     PKDescriptor(std::unique_ptr<PubkeyProvider> prov, bool xonly = false) : DescriptorImpl(Vector(std::move(prov)), "pk"), m_xonly(xonly) {}
+    std::optional<OutputType> GetOutputType() const override { return OutputType::LEGACY; }
     bool IsSingleType() const final { return true; }
 
     std::optional<int64_t> ScriptSize() const override {
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index c969ce45f1..2658c2a773 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -12,8 +12,6 @@
 #include <script/script.h>
 #include <uint256.h>
 
-typedef std::vector<unsigned char> valtype;
-
 namespace {
 
 inline bool set_success(ScriptError* ret)
@@ -60,7 +58,7 @@ static inline void popstack(std::vector<valtype>& stack)
     stack.pop_back();
 }
 
-bool static IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
+bool IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
     if (vchPubKey.size() < CPubKey::COMPRESSED_SIZE) {
         //  Non-canonical public key: too short
         return false;
@@ -104,7 +102,7 @@ bool static IsCompressedPubKey(const valtype &vchPubKey) {
  *
  * This function is consensus-critical since BIP66.
  */
-bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
+bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig, bool haveHashType = true) {
     // Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] [sighash]
     // * total-length: 1-byte length descriptor of everything that follows,
     //   excluding the sighash byte.
@@ -125,7 +123,7 @@ bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
     if (sig[0] != 0x30) return false;
 
     // Make sure the length covers the entire signature.
-    if (sig[1] != sig.size() - 3) return false;
+    if (sig[1] != sig.size() - (haveHashType ? 3 : 2)) return false;
 
     // Extract the length of the R element.
     unsigned int lenR = sig[3];
@@ -138,7 +136,7 @@ bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
 
     // Verify that the length of the signature matches the sum of the length
     // of the elements.
-    if ((size_t)(lenR + lenS + 7) != sig.size()) return false;
+    if ((size_t)(lenR + lenS + (haveHashType ? 7 : 6)) != sig.size()) return false;
 
     // Check whether the R element is an integer.
     if (sig[2] != 0x02) return false;
@@ -169,14 +167,14 @@ bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
     return true;
 }
 
-bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) {
-    if (!IsValidSignatureEncoding(vchSig)) {
+bool IsLowDERSignature(const valtype &vchSig, ScriptError* serror, bool haveHashType) {
+    if (!IsValidSignatureEncoding(vchSig, haveHashType)) {
         return set_error(serror, SCRIPT_ERR_SIG_DER);
     }
     // https://bitcoin.stackexchange.com/a/12556:
     //     Also note that inside transaction signatures, an extra hashtype byte
     //     follows the actual signature data.
-    std::vector<unsigned char> vchSigCopy(vchSig.begin(), vchSig.begin() + vchSig.size() - 1);
+    std::vector<unsigned char> vchSigCopy(vchSig.begin(), vchSig.begin() + vchSig.size() - (haveHashType ? 1 : 0));
     // If the S value is above the order of the curve divided by two, its
     // complement modulo the order could have been used instead, which is
     // one byte shorter when encoded correctly.
@@ -186,6 +184,13 @@ bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) {
     return true;
 }
 
+bool IsDERSignature(const valtype &vchSig, ScriptError* serror, bool haveHashType) {
+    if (!IsValidSignatureEncoding(vchSig, haveHashType)) {
+        return set_error(serror, SCRIPT_ERR_SIG_DER);
+    }
+    return true;
+}
+
 bool static IsDefinedHashtypeSignature(const valtype &vchSig) {
     if (vchSig.size() == 0) {
         return false;
@@ -1213,6 +1218,27 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 }
                 break;
 
+                //////////////////////////////////////////////////////// qtum
+                case OP_SENDER:
+                {
+                    if(!(flags & SCRIPT_OUTPUT_SENDER))
+                        return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
+                }
+                break;
+                case OP_SPEND:
+                {
+                    return true; // temp
+                }
+                break;
+                case OP_CREATE:
+                case OP_CALL:
+                {
+                    valtype scriptRest(pc - 1, pend);
+                    stack.push_back(scriptRest);
+                    return true; // temp
+                }
+                break;
+                ////////////////////////////////////////////////////////
                 default:
                     return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
             }
@@ -1360,6 +1386,22 @@ uint256 GetSequencesSHA256(const T& txTo)
     return ss.GetSHA256();
 }
 
+template <class T>
+uint256 GetFirstPrevoutSHA256(const T& txTo)
+{
+    HashWriter ss{};
+    ss << txTo.vin[0].prevout;
+    return ss.GetSHA256();
+}
+
+template <class T>
+uint256 GetFirstSequenceSHA256(const T& txTo)
+{
+    HashWriter ss{};
+    ss << txTo.vin[0].nSequence;
+    return ss.GetSHA256();
+}
+
 /** Compute the (single) SHA256 of the concatenation of all txouts of a tx. */
 template <class T>
 uint256 GetOutputsSHA256(const T& txTo)
@@ -1391,6 +1433,27 @@ uint256 GetSpentScriptsSHA256(const std::vector<CTxOut>& outputs_spent)
     return ss.GetSHA256();
 }
 
+CTxOut GetOutputWithoutSenderSig(const CTxOut& output)
+{
+    return CTxOut(output.nValue, output.scriptPubKey.WithoutSenderSig());
+}
+
+template <class T>
+uint256 GetOutputsOpSenderSHA256(const T& txTo)
+{
+    HashWriter ss{};
+    for (const auto& txout : txTo.vout) {
+        if(txout.scriptPubKey.HasOpSender())
+        {
+            ss << GetOutputWithoutSenderSig(txout);
+        }
+        else
+        {
+            ss << txout;
+        }
+    }
+    return ss.GetSHA256();
+}
 
 } // namespace
 
@@ -1408,6 +1471,7 @@ void PrecomputedTransactionData::Init(const T& txTo, std::vector<CTxOut>&& spent
     // Determine which precomputation-impacting features this transaction uses.
     bool uses_bip143_segwit = force;
     bool uses_bip341_taproot = force;
+    bool uses_op_sender = txTo.HasOpSender();
     for (size_t inpos = 0; inpos < txTo.vin.size() && !(uses_bip143_segwit && uses_bip341_taproot); ++inpos) {
         if (!txTo.vin[inpos].scriptWitness.IsNull()) {
             if (m_spent_outputs_ready && m_spent_outputs[inpos].scriptPubKey.size() == 2 + WITNESS_V1_TAPROOT_SIZE &&
@@ -1427,16 +1491,24 @@ void PrecomputedTransactionData::Init(const T& txTo, std::vector<CTxOut>&& spent
         if (uses_bip341_taproot && uses_bip143_segwit) break; // No need to scan further if we already need all.
     }
 
-    if (uses_bip143_segwit || uses_bip341_taproot) {
+    if (uses_bip143_segwit || uses_bip341_taproot || uses_op_sender) {
         // Computations shared between both sighash schemes.
         m_prevouts_single_hash = GetPrevoutsSHA256(txTo);
         m_sequences_single_hash = GetSequencesSHA256(txTo);
         m_outputs_single_hash = GetOutputsSHA256(txTo);
+        if(uses_op_sender)
+        {
+            m_outputs_opsender_single_hash = GetOutputsOpSenderSHA256(txTo);
+        }
     }
-    if (uses_bip143_segwit) {
+    if (uses_bip143_segwit || uses_op_sender) {
         hashPrevouts = SHA256Uint256(m_prevouts_single_hash);
         hashSequence = SHA256Uint256(m_sequences_single_hash);
         hashOutputs = SHA256Uint256(m_outputs_single_hash);
+        if(uses_op_sender)
+        {
+            hashOutputsOpSender = SHA256Uint256(m_outputs_opsender_single_hash);
+        }
         m_bip143_segwit_ready = true;
     }
     if (uses_bip341_taproot && m_spent_outputs_ready) {
@@ -1564,6 +1636,60 @@ bool SignatureHashSchnorr(uint256& hash_out, ScriptExecutionData& execdata, cons
     return true;
 }
 
+template <class T>
+uint256 SignatureHashOutput(const CScript& scriptCode, const T& txTo, unsigned int nOut, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache)
+{
+    assert(nOut < txTo.vout.size());
+
+    uint256 hashPrevouts;
+    uint256 hashSequence;
+    uint256 hashOutputs;
+    const bool cacheready = cache && cache->m_bip143_segwit_ready;
+
+    if (nHashType & SIGHASH_ANYONECANPAY) {
+        assert(0 < txTo.vin.size());
+        hashPrevouts = SHA256Uint256(GetFirstPrevoutSHA256(txTo));
+        hashSequence = SHA256Uint256(GetFirstSequenceSHA256(txTo));
+    }
+
+    if (!(nHashType & SIGHASH_ANYONECANPAY)) {
+        hashPrevouts = cacheready ? cache->hashPrevouts : SHA256Uint256(GetPrevoutsSHA256(txTo));
+    }
+
+    if (!(nHashType & SIGHASH_ANYONECANPAY) && (nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
+        hashSequence = cacheready ? cache->hashSequence : SHA256Uint256(GetSequencesSHA256(txTo));
+    }
+
+
+    if ((nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
+        hashOutputs = cacheready ? cache->hashOutputsOpSender : SHA256Uint256(GetOutputsOpSenderSHA256(txTo));
+    } else if ((nHashType & 0x1f) == SIGHASH_SINGLE && nOut < txTo.vout.size()) {
+        HashWriter ss{};
+        ss << GetOutputWithoutSenderSig(txTo.vout[nOut]);
+        hashOutputs = ss.GetHash();
+    }
+
+    HashWriter ss{};
+
+    // Version
+    ss << txTo.nVersion;
+    // Input prevouts/nSequence (none/first/all, depending on flags)
+    ss << hashPrevouts;
+    ss << hashSequence;
+    // The output being signed
+    ss << GetOutputWithoutSenderSig(txTo.vout[nOut]);
+    ss << scriptCode;
+    ss << amount;
+    // Outputs (none/one/all, depending on flags)
+    ss << hashOutputs;
+    // Locktime
+    ss << txTo.nLockTime;
+    // Sighash type
+    ss << nHashType;
+
+    return ss.GetHash();
+}
+
 template <class T>
 uint256 SignatureHash(const CScript& scriptCode, const T& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache)
 {
@@ -1785,6 +1911,38 @@ bool GenericTransactionSignatureChecker<T>::CheckSequence(const CScriptNum& nSeq
 template class GenericTransactionSignatureChecker<CTransaction>;
 template class GenericTransactionSignatureChecker<CMutableTransaction>;
 
+template <class T>
+bool GenericTransactionSignatureOutputChecker<T>::VerifyECDSASignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
+{
+    return pubkey.Verify(sighash, vchSig);
+}
+
+template <class T>
+bool GenericTransactionSignatureOutputChecker<T>::CheckECDSASignature(const std::vector<unsigned char>& vchSigIn, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
+{
+    CPubKey pubkey(vchPubKey);
+    if (!pubkey.IsValid())
+        return false;
+
+    // Hash type is one byte tacked on to the end of the signature
+    std::vector<unsigned char> vchSig(vchSigIn);
+    if (vchSig.empty())
+        return false;
+    int nHashType = vchSig.back();
+    vchSig.pop_back();
+
+    uint256 sighash = SignatureHashOutput(scriptCode, *txTo, nOut, nHashType, amount, sigversion, this->txdata);
+
+    if (!VerifyECDSASignature(vchSig, pubkey, sighash))
+        return false;
+
+    return true;
+}
+
+// explicit instantiation
+template class GenericTransactionSignatureOutputChecker<CTransaction>;
+template class GenericTransactionSignatureOutputChecker<CMutableTransaction>;
+
 static bool ExecuteWitnessScript(const Span<const valtype>& stack_span, const CScript& exec_script, unsigned int flags, SigVersion sigversion, const BaseSignatureChecker& checker, ScriptExecutionData& execdata, ScriptError* serror)
 {
     std::vector<valtype> stack{stack_span.begin(), stack_span.end()};
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index 836c2e7982..cd681d28a3 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -24,6 +24,8 @@ class CScriptNum;
 class XOnlyPubKey;
 struct CScriptWitness;
 
+typedef std::vector<unsigned char> valtype;
+
 /** Signature hash types/flags */
 enum
 {
@@ -143,6 +145,14 @@ enum : uint32_t {
     // Making unknown public key versions (in BIP 342 scripts) non-standard
     SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE = (1U << 20),
 
+    // Support sender address in contract output
+    //
+    SCRIPT_OUTPUT_SENDER = (1U << 29),
+
+    // Performs the compiled byte code
+    //
+    SCRIPT_EXEC_BYTE_CODE = (1U << 30),
+
     // Constants to point to the highest flag in use. Add new flags above this line.
     //
     SCRIPT_VERIFY_END_MARKER
@@ -157,13 +167,14 @@ struct PrecomputedTransactionData
     uint256 m_prevouts_single_hash;
     uint256 m_sequences_single_hash;
     uint256 m_outputs_single_hash;
+    uint256 m_outputs_opsender_single_hash;
     uint256 m_spent_amounts_single_hash;
     uint256 m_spent_scripts_single_hash;
     //! Whether the 5 fields above are initialized.
     bool m_bip341_taproot_ready = false;
 
     // BIP143 precomputed data (double-SHA256).
-    uint256 hashPrevouts, hashSequence, hashOutputs;
+    uint256 hashPrevouts, hashSequence, hashOutputs, hashOutputsOpSender;
     //! Whether the 3 fields above are initialized.
     bool m_bip143_segwit_ready = false;
 
@@ -242,6 +253,9 @@ extern const HashWriter HASHER_TAPBRANCH;  //!< Hasher with tag "TapBranch" pre-
 template <class T>
 uint256 SignatureHash(const CScript& scriptCode, const T& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache = nullptr);
 
+template <class T>
+uint256 SignatureHashOutput(const CScript& scriptCode, const T& txTo, unsigned int nOut, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache = nullptr);
+
 class BaseSignatureChecker
 {
 public:
@@ -334,6 +348,27 @@ class DeferringSignatureChecker : public BaseSignatureChecker
     }
 };
 
+template <class T>
+class GenericTransactionSignatureOutputChecker : public BaseSignatureChecker
+{
+private:
+    const T* txTo;
+    unsigned int nOut;
+    const CAmount amount;
+    const PrecomputedTransactionData* txdata;
+
+protected:
+    virtual bool VerifyECDSASignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
+
+public:
+    GenericTransactionSignatureOutputChecker(const T* txToIn, unsigned int nOutIn, const CAmount& amountIn) : txTo(txToIn), nOut(nOutIn), amount(amountIn), txdata(nullptr) {}
+    GenericTransactionSignatureOutputChecker(const T* txToIn, unsigned int nOutIn, const CAmount& amountIn, const PrecomputedTransactionData& txdataIn) : txTo(txToIn), nOut(nOutIn), amount(amountIn), txdata(&txdataIn) {}
+    bool CheckECDSASignature(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override;
+};
+
+using TransactionSignatureOutputChecker = GenericTransactionSignatureOutputChecker<CTransaction>;
+using MutableTransactionSignatureOutputChecker = GenericTransactionSignatureOutputChecker<CMutableTransaction>;
+
 /** Compute the BIP341 tapleaf hash from leaf version & script. */
 uint256 ComputeTapleafHash(uint8_t leaf_version, Span<const unsigned char> script);
 /** Compute the BIP341 tapbranch hash from two branches.
@@ -351,4 +386,8 @@ size_t CountWitnessSigOps(const CScript& scriptSig, const CScript& scriptPubKey,
 
 int FindAndDelete(CScript& script, const CScript& b);
 
+bool IsLowDERSignature(const valtype &vchSig, ScriptError* serror = NULL, bool haveHashType = true);
+bool IsDERSignature(const valtype &vchSig, ScriptError* serror = NULL, bool haveHashType = true);
+bool IsCompressedOrUncompressedPubKey(const valtype &vchPubKey);
+
 #endif // BITCOIN_SCRIPT_INTERPRETER_H
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp
index 7c6c282cc4..1206cad19f 100644
--- a/src/script/sigcache.cpp
+++ b/src/script/sigcache.cpp
@@ -127,3 +127,16 @@ bool CachingTransactionSignatureChecker::VerifySchnorrSignature(Span<const unsig
     if (store) signatureCache.Set(entry);
     return true;
 }
+
+bool CachingTransactionSignatureOutputChecker::VerifyECDSASignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
+{
+    uint256 entry;
+    signatureCache.ComputeEntryECDSA(entry, sighash, vchSig, pubkey);
+    if (signatureCache.Get(entry, !store))
+        return true;
+    if (!TransactionSignatureOutputChecker::VerifyECDSASignature(vchSig, pubkey, sighash))
+        return false;
+    if (store)
+        signatureCache.Set(entry);
+    return true;
+}
diff --git a/src/script/sigcache.h b/src/script/sigcache.h
index d33d60d5bc..eb6c768e50 100644
--- a/src/script/sigcache.h
+++ b/src/script/sigcache.h
@@ -32,6 +32,17 @@ class CachingTransactionSignatureChecker : public TransactionSignatureChecker
     bool VerifySchnorrSignature(Span<const unsigned char> sig, const XOnlyPubKey& pubkey, const uint256& sighash) const override;
 };
 
+class CachingTransactionSignatureOutputChecker : public TransactionSignatureOutputChecker
+{
+private:
+    bool store;
+
+public:
+    CachingTransactionSignatureOutputChecker(const CTransaction* txToIn, unsigned int nOutIn, const CAmount& amountIn, bool storeIn, PrecomputedTransactionData& txdataIn) : TransactionSignatureOutputChecker(txToIn, nOutIn, amountIn, txdataIn), store(storeIn) {}
+
+    bool VerifyECDSASignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const override;
+};
+
 [[nodiscard]] bool InitSignatureCache(size_t max_size_bytes);
 
 #endif // BITCOIN_SCRIPT_SIGCACHE_H
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index be4b357568..add9f9f792 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -17,6 +17,7 @@
 #include <uint256.h>
 #include <util/translation.h>
 #include <util/vector.h>
+#include <span.h>
 
 typedef std::vector<unsigned char> valtype;
 
@@ -90,6 +91,26 @@ bool MutableTransactionSignatureCreator::CreateSchnorrSig(const SigningProvider&
     return true;
 }
 
+MutableTransactionSignatureOutputCreator::MutableTransactionSignatureOutputCreator(const CMutableTransaction& txToIn, unsigned int nOutIn, const CAmount& amountIn, int nHashTypeIn) : m_txto(txToIn), nOut(nOutIn), nHashType(nHashTypeIn), amount(amountIn), checker(&m_txto, nOut, amountIn) {}
+
+bool MutableTransactionSignatureOutputCreator::CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& address, const CScript& scriptCode, SigVersion sigversion) const
+{
+    CKey key;
+    if (!provider.GetKey(address, key))
+        return false;
+
+    uint256 hash = SignatureHashOutput(scriptCode, m_txto, nOut, nHashType, amount, sigversion);
+    if (!key.Sign(hash, vchSig))
+        return false;
+    vchSig.push_back((unsigned char)nHashType);
+    return true;
+}
+
+bool MutableTransactionSignatureOutputCreator::CreateSchnorrSig(const SigningProvider &, std::vector<unsigned char> &, const XOnlyPubKey &, const uint256 *, const uint256 *, SigVersion ) const
+{
+    return false;
+}
+
 static bool GetCScript(const SigningProvider& provider, const SignatureData& sigdata, const CScriptID& scriptid, CScript& script)
 {
     if (provider.GetCScript(scriptid, script)) {
@@ -412,6 +433,10 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
     case TxoutType::NONSTANDARD:
     case TxoutType::NULL_DATA:
     case TxoutType::WITNESS_UNKNOWN:
+    case TxoutType::CREATE_SENDER:
+    case TxoutType::CALL_SENDER:
+    case TxoutType::CREATE:
+    case TxoutType::CALL:
         return false;
     case TxoutType::PUBKEY:
         if (!CreateSig(creator, sigdata, provider, sig, CPubKey(vSolutions[0]), scriptPubKey, sigversion)) return false;
@@ -712,6 +737,35 @@ bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom,
     return SignSignature(provider, txout.scriptPubKey, txTo, nIn, txout.nValue, nHashType, sig_data);
 }
 
+bool VerifySignature(const Coin& coin, const uint256 txFromHash, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
+{
+    TransactionSignatureChecker checker(&txTo, nIn, 0, MissingDataBehavior::FAIL);
+	
+    const CTxIn& txin = txTo.vin[nIn];
+//    if (txin.prevout.n >= txFrom.vout.size())
+//        return false;
+//    const CTxOut& txout = txFrom.vout[txin.prevout.n];
+
+    const CTxOut& txout = coin.out;
+
+    if (txin.prevout.hash != txFromHash)
+        return false;
+		
+    return VerifyScript(txin.scriptSig, txout.scriptPubKey, NULL, flags, checker);
+}
+
+bool VerifySignature(const CScript& fromPubKey, const uint256 txFromHash, const CTransaction& txTo, unsigned int nIn, unsigned int flags)
+{
+    TransactionSignatureChecker checker(&txTo, nIn, 0, MissingDataBehavior::FAIL);
+	
+    const CTxIn& txin = txTo.vin[nIn];
+
+    if (txin.prevout.hash != txFromHash)
+        return false;
+		
+    return VerifyScript(txin.scriptSig, fromPubKey, NULL, flags, checker);
+}
+
 namespace {
 /** Dummy signature checker which accepts all signatures. */
 class DummySignatureChecker final : public BaseSignatureChecker
@@ -848,3 +902,87 @@ bool SignTransaction(CMutableTransaction& mtx, const SigningProvider* keystore,
     }
     return input_errors.empty();
 }
+
+bool UpdateOutput(CTxOut &output, const SignatureData &data)
+{
+    bool ret = false;
+    DataStream streamSig;
+    streamSig << data.scriptSig;
+    CScript scriptPubKey;
+    if(output.scriptPubKey.UpdateSenderSig(ToByteVector(MakeUCharSpan(streamSig)), scriptPubKey))
+    {
+        output.scriptPubKey = scriptPubKey;
+        ret = true;
+    }
+    return ret;
+}
+
+bool SignTransactionOutput(CMutableTransaction &mtx, const SigningProvider *provider, int nHashType, std::map<int, std::string>& output_errors)
+{
+    // Signing transaction outputs
+    for (unsigned int i = 0; i < mtx.vout.size(); i++)
+    {
+        CTxOut& output = mtx.vout[i];
+        if(output.scriptPubKey.HasOpSender())
+        {
+            CScript scriptPubKey;
+            if(!GetSenderPubKey(output.scriptPubKey, scriptPubKey))
+            {
+                output_errors[i] = "Fail to get sender public key";
+                continue;
+            }
+
+            SignatureData sigdata;
+            if (!ProduceSignature(*provider, MutableTransactionSignatureOutputCreator(mtx, i, output.nValue, nHashType), scriptPubKey, sigdata))
+            {
+                output_errors[i] = "Signing transaction output failed";
+                continue;
+            }
+            else
+            {
+                if(UpdateOutput(output, sigdata))
+                {
+                    output_errors.erase(i);
+                }
+                else
+                {
+                    output_errors[i] = "Update transaction output failed";
+                    continue;
+                }
+            }
+        }
+    }
+    return output_errors.empty();
+}
+
+bool SignTransactionStake(CMutableTransaction &mtx, const SigningProvider *provider, const std::vector<std::pair<CTxOut, unsigned int> > &coins)
+{
+    for(const std::pair<const CTxOut&,unsigned int> &pcoin : coins)
+    {
+        const CTxOut& txout = pcoin.first;
+        unsigned int nIn = pcoin.second;
+        SignatureData sigdata;
+        if (!SignSignature(*provider, txout.scriptPubKey, mtx, nIn, txout.nValue, SIGHASH_ALL, sigdata))
+            return false;
+    }
+
+    return true;
+}
+
+bool SignBlockStake(CBlock &block, CKey &key, bool compact)
+{
+    bool isSigned = false;
+    if(compact)
+    {
+        // append a signature to our block and ensure that is compact
+        std::vector<unsigned char> vchSig;
+        isSigned = key.SignCompact(block.GetHashWithoutSign(), vchSig);
+        block.SetBlockSignature(vchSig);
+    }
+    else
+    {
+        isSigned = key.Sign(block.GetHashWithoutSign(), block.vchBlockSigDlgt);
+    }
+
+    return isSigned;
+}
diff --git a/src/script/sign.h b/src/script/sign.h
index ace2ba7856..bef9b31327 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -14,6 +14,8 @@
 #include <script/keyorigin.h>
 #include <script/signingprovider.h>
 #include <uint256.h>
+#include <streams.h>
+#include <coins.h>
 
 class CKey;
 class CKeyID;
@@ -53,6 +55,21 @@ class MutableTransactionSignatureCreator : public BaseSignatureCreator
     bool CreateSchnorrSig(const SigningProvider& provider, std::vector<unsigned char>& sig, const XOnlyPubKey& pubkey, const uint256* leaf_hash, const uint256* merkle_root, SigVersion sigversion) const override;
 };
 
+/** A signature creator for transactions outputs. */
+class MutableTransactionSignatureOutputCreator : public BaseSignatureCreator {
+    const CMutableTransaction& m_txto;
+    unsigned int nOut;
+    int nHashType;
+    CAmount amount;
+    const MutableTransactionSignatureOutputChecker checker;
+
+public:
+    MutableTransactionSignatureOutputCreator(const CMutableTransaction& txToIn LIFETIMEBOUND, unsigned int nOutIn, const CAmount& amountIn, int nHashTypeIn = SIGHASH_ALL);
+    const BaseSignatureChecker& Checker() const override { return checker; }
+    bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const override;
+    bool CreateSchnorrSig(const SigningProvider& provider, std::vector<unsigned char>& sig, const XOnlyPubKey& pubkey, const uint256* leaf_hash, const uint256* merkle_root, SigVersion sigversion) const override;
+};
+
 /** A signature checker that accepts all signatures */
 extern const BaseSignatureChecker& DUMMY_CHECKER;
 /** A signature creator that just produces 71-byte empty signatures. */
@@ -115,15 +132,28 @@ bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, C
                    unsigned int nIn, const CAmount& amount, int nHashType, SignatureData& sig_data);
 bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo,
                    unsigned int nIn, int nHashType, SignatureData& sig_data);
+bool VerifySignature(const Coin& coin, uint256 txFromHash, const CTransaction& txTo, unsigned int nIn, unsigned int flags);
+bool VerifySignature(const CScript& fromPubKey, uint256 txFromHash, const CTransaction& txTo, unsigned int nIn, unsigned int flags);
 
 /** Extract signature data from a transaction input, and insert it. */
 SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);
 void UpdateInput(CTxIn& input, const SignatureData& data);
 
+bool UpdateOutput(CTxOut& output, const SignatureData& data);
+
 /** Check whether a scriptPubKey is known to be segwit. */
 bool IsSegWitOutput(const SigningProvider& provider, const CScript& script);
 
 /** Sign the CMutableTransaction */
 bool SignTransaction(CMutableTransaction& mtx, const SigningProvider* provider, const std::map<COutPoint, Coin>& coins, int sighash, std::map<int, bilingual_str>& input_errors);
 
+/** Sign output in the CMutableTransaction */
+bool SignTransactionOutput(CMutableTransaction& mtx, const SigningProvider* provider, int sighash, std::map<int, std::string>& output_errors);
+
+/** Sign stake in the CMutableTransaction */
+bool SignTransactionStake(CMutableTransaction& mtx, const SigningProvider* provider, const std::vector<std::pair<CTxOut,unsigned int>>& coins);
+
+/** Sign stake in the CBlock */
+bool SignBlockStake(CBlock& block, CKey& key, bool compact);
+
 #endif // BITCOIN_SCRIPT_SIGN_H
diff --git a/src/script/solver.cpp b/src/script/solver.cpp
index 3dfa9cd6ba..5271e9a01a 100644
--- a/src/script/solver.cpp
+++ b/src/script/solver.cpp
@@ -12,6 +12,7 @@
 #include <algorithm>
 #include <cassert>
 #include <string>
+#include <streams.h>
 
 typedef std::vector<unsigned char> valtype;
 
@@ -137,7 +138,7 @@ std::optional<std::pair<int, std::vector<Span<const unsigned char>>>> MatchMulti
     return std::pair{*threshold, std::move(keyspans)};
 }
 
-TxoutType Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet)
+TxoutType Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet, bool contractConsensus, bool allowEmptySenderSig)
 {
     vSolutionsRet.clear();
 
@@ -222,3 +223,73 @@ CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
 
     return script;
 }
+
+bool ExtractSenderData(const CScript &outputPubKey, CScript *senderPubKey, CScript *senderSig)
+{
+    if(outputPubKey.HasOpSender())
+    {
+        try
+        {
+            // Solve the contract with or without contract consensus
+            std::vector<valtype> vSolutions;
+            if (TxoutType::NONSTANDARD == Solver(outputPubKey, vSolutions, true) &&
+                    TxoutType::NONSTANDARD == Solver(outputPubKey, vSolutions, false))
+                return false;
+
+            // Check the size of the returned data
+            if(vSolutions.size() < 2)
+                return false;
+
+            // Get the sender public key
+            if(senderPubKey)
+            {
+                DataStream ss(vSolutions[0]);
+                ss >> *senderPubKey;
+            }
+
+            // Get the sender signature
+            if(senderSig)
+            {
+                DataStream ss(vSolutions[1]);
+                ss >> *senderSig;
+            }
+        }
+        catch(...)
+        {
+            return false;
+        }
+
+        return true;
+    }
+    return false;
+}
+
+bool GetSenderPubKey(const CScript &outputPubKey, CScript &senderPubKey)
+{
+    if(outputPubKey.HasOpSender())
+    {
+        try
+        {
+            // Solve the contract with or without contract consensus
+            std::vector<valtype> vSolutions;
+            if (TxoutType::NONSTANDARD == Solver(outputPubKey, vSolutions, true, true) &&
+                    TxoutType::NONSTANDARD == Solver(outputPubKey, vSolutions, false, true))
+                return false;
+
+            // Check the size of the returned data
+            if(vSolutions.size() < 1)
+                return false;
+
+            // Get the sender public key
+            DataStream ss(vSolutions[0]);
+            ss >> senderPubKey;
+        }
+        catch(...)
+        {
+            return false;
+        }
+
+        return true;
+    }
+    return false;
+}
diff --git a/src/script/solver.h b/src/script/solver.h
index dc8f4c357d..6392451452 100644
--- a/src/script/solver.h
+++ b/src/script/solver.h
@@ -19,6 +19,13 @@
 class CPubKey;
 template <typename C> class Span;
 
+//contract executions with less gas than this are not standard
+//Make sure is always equal or greater than MINIMUM_GAS_LIMIT (which we can't reference here due to insane header dependency chains)
+static const uint64_t STANDARD_MINIMUM_GAS_LIMIT = 10000;
+//contract executions with a price cheaper than this (in satoshis) are not standard
+//TODO this needs to be controlled by DGP and needs to be propagated from consensus parameters
+static const uint64_t STANDARD_MINIMUM_GAS_PRICE = 1;
+
 enum class TxoutType {
     NONSTANDARD,
     // 'standard' transaction types:
@@ -31,6 +38,10 @@ enum class TxoutType {
     WITNESS_V0_KEYHASH,
     WITNESS_V1_TAPROOT,
     WITNESS_UNKNOWN, //!< Only for Witness versions not already defined above
+    CREATE_SENDER,
+    CALL_SENDER,
+    CREATE,
+    CALL,
 };
 
 /** Get the name of a TxoutType as a string */
@@ -41,6 +52,11 @@ constexpr bool IsPushdataOp(opcodetype opcode)
     return opcode > OP_FALSE && opcode <= OP_PUSHDATA4;
 }
 
+/** Parse a output public key for the sender public key and sender signature. */
+bool ExtractSenderData(const CScript& outputPubKey, CScript* senderPubKey, CScript* senderSig);
+
+bool GetSenderPubKey(const CScript& outputPubKey, CScript& senderPubKey);
+
 /**
  * Parse a scriptPubKey and identify script type for standard scripts. If
  * successful, returns script type and parsed pubkeys or hashes, depending on
@@ -51,7 +67,7 @@ constexpr bool IsPushdataOp(opcodetype opcode)
  * @param[out]  vSolutionsRet  Vector of parsed pubkeys and hashes
  * @return                     The script type. TxoutType::NONSTANDARD represents a failed solve.
  */
-TxoutType Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet);
+TxoutType Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet, bool contractConsensus=false, bool allowEmptySenderSig=false);
 
 /** Generate a P2PK script for the given pubkey. */
 CScript GetScriptForRawPubKey(const CPubKey& pubkey);