diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index d10b1c4fd7..fa09adbaf8 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -11,7 +11,6 @@
 #include <script/standard.h>
 #include <uint256.h>
 
-
 typedef std::vector<unsigned char> valtype;
 
 MutableTransactionSignatureCreator::MutableTransactionSignatureCreator(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn) : txTo(txToIn), nIn(nInIn), nHashType(nHashTypeIn), amount(amountIn), checker(txTo, nIn, amountIn) {}
@@ -437,6 +436,18 @@ public:
         return true;
     }
 };
+
+template<typename M, typename K, typename V>
+bool LookupHelper(const M& map, const K& key, V& value)
+{
+    auto it = map.find(key);
+    if (it != map.end()) {
+        value = it->second;
+        return true;
+    }
+    return false;
+}
+
 }
 
 const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR = DummySignatureCreator();
@@ -460,7 +471,6 @@ bool IsSolvable(const SigningProvider& provider, const CScript& script)
     return false;
 }
 
-
 bool PartiallySignedTransaction::IsNull() const
 {
     return !tx && inputs.empty() && outputs.empty() && unknown.empty();
@@ -618,3 +628,19 @@ bool PublicOnlySigningProvider::GetPubKey(const CKeyID &address, CPubKey& pubkey
 {
     return m_provider->GetPubKey(address, pubkey);
 }
+
+bool FlatSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const { return LookupHelper(scripts, scriptid, script); }
+bool FlatSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const { return LookupHelper(pubkeys, keyid, pubkey); }
+bool FlatSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const { return LookupHelper(keys, keyid, key); }
+
+FlatSigningProvider Merge(const FlatSigningProvider& a, const FlatSigningProvider& b)
+{
+    FlatSigningProvider ret;
+    ret.scripts = a.scripts;
+    ret.scripts.insert(b.scripts.begin(), b.scripts.end());
+    ret.pubkeys = a.pubkeys;
+    ret.pubkeys.insert(b.pubkeys.begin(), b.pubkeys.end());
+    ret.keys = a.keys;
+    ret.keys.insert(b.keys.begin(), b.keys.end());
+    return ret;
+}
diff --git a/src/script/sign.h b/src/script/sign.h
index d12d0b5874..96ef59fbe8 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -43,6 +43,19 @@ public:
     bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const;
 };
 
+struct FlatSigningProvider final : public SigningProvider
+{
+    std::map<CScriptID, CScript> scripts;
+    std::map<CKeyID, CPubKey> pubkeys;
+    std::map<CKeyID, CKey> keys;
+
+    bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
+    bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
+    bool GetKey(const CKeyID& keyid, CKey& key) const override;
+};
+
+FlatSigningProvider Merge(const FlatSigningProvider& a, const FlatSigningProvider& b);
+
 /** Interface for signature creators. */
 class BaseSignatureCreator {
 public: