Merge #13425: Moving final scriptSig construction from CombineSignatures to ProduceSignature (PSBT signer logic)

b815600 Remove CombineSignatures and replace tests (Andrew Chow)
ed94c8b Replace CombineSignatures with ProduceSignature (Andrew Chow)
0422beb Make SignatureData able to store signatures and scripts (Andrew Chow)
b6edb4f Inline Sign1 and SignN (Andrew Chow)

Pull request description:

  Currently CombineSignatures is used to create the final scriptSig or an input. However ProduceSignature is capable of doing this itself. Using both CombineSignatures and ProduceSignature results in code duplication which is unnecessary.

  To move the scriptSig construction to ProduceSignatures, the SignatureData class contains two maps to hold pubkeys mapped to signatures, and script ids mapped to scripts. DataFromTransaction is extended to be able to extract signatures, their public keys, and scripts from existing ScriptSigs.

  The SignaureData are then passed down to SignStep which can use the aforementioned maps to get the signatures, pubkeys, and scripts that it needs, falling back to the actual SigningProvider and SignatureCreator if the data are not available in the SignatureData.

  Additionally, Sign1 and SignN have been removed and their functionality inlined into SignStep since Sign1 is really just a wrapper around CreateSig.

  Since ProduceSignature can produce the final scriptSig or scriptWitness by using SignatureData which has extracted data from the transaction, CombineSignatures is unnecessary as ProduceSignature is able to replicate all of CombineSignatures' functionality.

  This also furthers BIP 174 support and begins moving towards a BIP 174 style backend.

  The tests have also been updated to use the new combining methodology.

Tree-SHA512: 78cd58a4ebe37f79229bd5eee2958a0bb45cd7f36d0e993eee13ff685b3665dd76ef2dfd5f47d34678995bb587f5594100ee5f6c09b1c69ee96d3684d470d01e

Author: laanwj

src/bench/verify_script.cpp

@@ -9,6 +9,7 @@
 #endif
 #include <script/script.h>
 #include <script/sign.h>
+#include <script/standard.h>
 #include <streams.h>
 
 #include <array>

src/bitcoin-tx.cpp

@@ -645,13 +645,11 @@ static void MutateTxSign(CMutableTransaction& tx, const std::string& flagStr)
         const CScript& prevPubKey = coin.out.scriptPubKey;
         const CAmount& amount = coin.out.nValue;
 
-        SignatureData sigdata;
+        SignatureData sigdata = DataFromTransaction(mergedTx, i, coin.out);
         // Only sign SIGHASH_SINGLE if there's a corresponding output:
         if (!fHashSingle || (i < mergedTx.vout.size()))
             ProduceSignature(keystore, MutableTransactionSignatureCreator(&mergedTx, i, amount, nHashType), prevPubKey, sigdata);
 
-        // ... and merge in other signatures:
-        sigdata = CombineSignatures(prevPubKey, MutableTransactionSignatureChecker(&mergedTx, i, amount), sigdata, DataFromTransaction(txv, i));
         UpdateInput(txin, sigdata);
     }
 

src/rpc/rawtransaction.cpp

@@ -733,17 +733,15 @@ static UniValue combinerawtransaction(const JSONRPCRequest& request)
         if (coin.IsSpent()) {
             throw JSONRPCError(RPC_VERIFY_ERROR, "Input not found or already spent");
         }
-        const CScript& prevPubKey = coin.out.scriptPubKey;
-        const CAmount& amount = coin.out.nValue;
-
         SignatureData sigdata;
 
         // ... and merge in other signatures:
         for (const CMutableTransaction& txv : txVariants) {
             if (txv.vin.size() > i) {
-                sigdata = CombineSignatures(prevPubKey, TransactionSignatureChecker(&txConst, i, amount), sigdata, DataFromTransaction(txv, i));
+                sigdata.MergeSignatureData(DataFromTransaction(txv, i, coin.out));
             }
         }
+        ProduceSignature(DUMMY_SIGNING_PROVIDER, MutableTransactionSignatureCreator(&mergedTx, i, coin.out.nValue, 1), coin.out.scriptPubKey, sigdata);
 
         UpdateInput(txin, sigdata);
     }
@@ -872,12 +870,11 @@ UniValue SignTransaction(CMutableTransaction& mtx, const UniValue& prevTxsUnival
         const CScript& prevPubKey = coin.out.scriptPubKey;
         const CAmount& amount = coin.out.nValue;
 
-        SignatureData sigdata;
+        SignatureData sigdata = DataFromTransaction(mtx, i, coin.out);
         // Only sign SIGHASH_SINGLE if there's a corresponding output:
         if (!fHashSingle || (i < mtx.vout.size())) {
             ProduceSignature(*keystore, MutableTransactionSignatureCreator(&mtx, i, amount, nHashType), prevPubKey, sigdata);
         }
-        sigdata = CombineSignatures(prevPubKey, TransactionSignatureChecker(&txConst, i, amount), sigdata, DataFromTransaction(mtx, i));
 
         UpdateInput(txin, sigdata);