tests: abstract out precomputed BIP341 signature hash elements

Author: sipa

test/functional/test_framework/script.py

@@ -755,6 +755,21 @@ def test_cscriptnum_encoding(self):
         for value in values:
             self.assertEqual(CScriptNum.decode(CScriptNum.encode(CScriptNum(value))), value)
 
+def BIP341_sha_prevouts(txTo):
+    return sha256(b"".join(i.prevout.serialize() for i in txTo.vin))
+
+def BIP341_sha_amounts(spent_utxos):
+    return sha256(b"".join(struct.pack("<q", u.nValue) for u in spent_utxos))
+
+def BIP341_sha_scriptpubkeys(spent_utxos):
+    return sha256(b"".join(ser_string(u.scriptPubKey) for u in spent_utxos))
+
+def BIP341_sha_sequences(txTo):
+    return sha256(b"".join(struct.pack("<I", i.nSequence) for i in txTo.vin))
+
+def BIP341_sha_outputs(txTo):
+    return sha256(b"".join(o.serialize() for o in txTo.vout))
+
 def TaprootSignatureMsg(txTo, spent_utxos, hash_type, input_index = 0, scriptpath = False, script = CScript(), codeseparator_pos = -1, annex = None, leaf_ver = LEAF_VERSION_TAPSCRIPT):
     assert (len(txTo.vin) == len(spent_utxos))
     assert (input_index < len(txTo.vin))
@@ -765,12 +780,12 @@ def TaprootSignatureMsg(txTo, spent_utxos, hash_type, input_index = 0, scriptpat
     ss += struct.pack("<i", txTo.nVersion)
     ss += struct.pack("<I", txTo.nLockTime)
     if in_type != SIGHASH_ANYONECANPAY:
-        ss += sha256(b"".join(i.prevout.serialize() for i in txTo.vin))
-        ss += sha256(b"".join(struct.pack("<q", u.nValue) for u in spent_utxos))
-        ss += sha256(b"".join(ser_string(u.scriptPubKey) for u in spent_utxos))
-        ss += sha256(b"".join(struct.pack("<I", i.nSequence) for i in txTo.vin))
+        ss += BIP341_sha_prevouts(txTo)
+        ss += BIP341_sha_amounts(spent_utxos)
+        ss += BIP341_sha_scriptpubkeys(spent_utxos)
+        ss += BIP341_sha_sequences(txTo)
     if out_type == SIGHASH_ALL:
-        ss += sha256(b"".join(o.serialize() for o in txTo.vout))
+        ss += BIP341_sha_outputs(txTo)
     spend_type = 0
     if annex is not None:
         spend_type |= 1