transaction.py: shortcut witness/scriptSig serialisation

lib/bitcoin.py

@@ -188,6 +188,13 @@ def var_int(i):
         return "ff"+int_to_hex(i,8)
 
 
+def witness_push(item):
+    """ Returns data in the form it should be present in the witness.
+    hex -> hex
+    """
+    return var_int(len(item) // 2) + item
+
+
 def op_push(i):
     if i<0x4c:  # OP_PUSHDATA1
         return int_to_hex(i)

lib/transaction.py

@@ -359,8 +359,9 @@ def parse_scriptSig(d, _bytes):
     match = [ opcodes.OP_0 ] + [ opcodes.OP_PUSHDATA4 ] * (len(decoded) - 1)
     if match_decoded(decoded, match):
         x_sig = [bh2u(x[1]) for x in decoded[1:-1]]
+        redeem_script = bh2u(decoded[-1][1])
         try:
-            m, n, x_pubkeys, pubkeys, redeemScript = parse_redeemScript(decoded[-1][1])
+            m, n, x_pubkeys, pubkeys = parse_redeemScript_multisig(bfh(redeem_script))
         except NotRecognizedRedeemScript:
             print_error("parse_scriptSig: cannot find address in input script (p2sh?)",
                         bh2u(_bytes))
@@ -373,16 +374,16 @@ def parse_scriptSig(d, _bytes):
         d['signatures'] = parse_sig(x_sig)
         d['x_pubkeys'] = x_pubkeys
         d['pubkeys'] = pubkeys
-        d['redeemScript'] = redeemScript
+        d['redeem_script'] = redeem_script
-        d['address'] = hash160_to_p2sh(hash_160(bfh(redeemScript)))
+        d['address'] = hash160_to_p2sh(hash_160(bfh(redeem_script)))
         return
 
     print_error("parse_scriptSig: cannot find address in input script (unknown)",
                 bh2u(_bytes))
 
 
-def parse_redeemScript(s):
+def parse_redeemScript_multisig(redeem_script):
-    dec2 = [ x for x in script_GetOp(s) ]
+    dec2 = [ x for x in script_GetOp(redeem_script) ]
     try:
         m = dec2[0][0] - opcodes.OP_1 + 1
         n = dec2[-2][0] - opcodes.OP_1 + 1
@@ -395,8 +396,10 @@ def parse_redeemScript(s):
         raise NotRecognizedRedeemScript()
     x_pubkeys = [bh2u(x[1]) for x in dec2[1:-2]]
     pubkeys = [safe_parse_pubkey(x) for x in x_pubkeys]
-    redeemScript = multisig_script(pubkeys, m)
+    redeem_script2 = bfh(multisig_script(pubkeys, m))
-    return m, n, x_pubkeys, pubkeys, redeemScript
+    if redeem_script2 != redeem_script:
+        raise NotRecognizedRedeemScript()
+    return m, n, x_pubkeys, pubkeys
 
 
 def get_address_from_output_script(_bytes, *, net=None):
@@ -471,8 +474,7 @@ def parse_witness(vds, txin):
     # now 'n' is the number of items in the witness
     w = list(bh2u(vds.read_bytes(vds.read_compact_size())) for i in range(n))
 
-    add_w = lambda x: var_int(len(x) // 2) + x
+    txin['witness'] = var_int(n) + ''.join(witness_push(i) for i in w)
-    txin['witness'] = var_int(n) + ''.join(add_w(i) for i in w)
 
     # FIXME: witness version > 0 will probably fail here.
     # For native segwit, we would need the scriptPubKey of the parent txn
@@ -487,18 +489,19 @@ def parse_witness(vds, txin):
         if txin['type'] == 'coinbase':
             pass
         elif txin['type'] == 'p2wsh-p2sh' or n > 2:
+            witness_script = w[-1]
             try:
-                m, n, x_pubkeys, pubkeys, witnessScript = parse_redeemScript(bfh(w[-1]))
+                m, n, x_pubkeys, pubkeys = parse_redeemScript_multisig(bfh(witness_script))
             except NotRecognizedRedeemScript:
                 raise UnknownTxinType()
             txin['signatures'] = parse_sig(w[1:-1])
             txin['num_sig'] = m
             txin['x_pubkeys'] = x_pubkeys
             txin['pubkeys'] = pubkeys
-            txin['witnessScript'] = witnessScript
+            txin['witness_script'] = witness_script
             if not txin.get('scriptSig'):  # native segwit script
                 txin['type'] = 'p2wsh'
-                txin['address'] = bitcoin.script_to_p2wsh(txin['witnessScript'])
+                txin['address'] = bitcoin.script_to_p2wsh(witness_script)
         elif txin['type'] == 'p2wpkh-p2sh' or n == 2:
             txin['num_sig'] = 1
             txin['x_pubkeys'] = [w[1]]
@@ -641,12 +644,18 @@ class Transaction:
                         public_key.verify_digest(sig_string, pre_hash, sigdecode = ecdsa.util.sigdecode_string)
                         j = pubkeys.index(pubkey)
                         print_error("adding sig", i, j, pubkey, sig)
-                        self._inputs[i]['signatures'][j] = sig
+                        self.add_signature_to_txin(self._inputs[i], j, sig)
                         #self._inputs[i]['x_pubkeys'][j] = pubkey
                         break
         # redo raw
         self.raw = self.serialize()
 
+    @classmethod
+    def add_signature_to_txin(cls, txin, signingPos, sig):
+        txin['signatures'][signingPos] = sig
+        txin['scriptSig'] = None  # force re-serialization
+        txin['witness'] = None    # force re-serialization
+
     def deserialize(self):
         if self.raw is None:
             return
@@ -736,17 +745,17 @@ class Transaction:
             return '00'
         if txin['type'] == 'coinbase':
             return txin['witness']
+
+        witness = txin.get('witness', None)
+        if witness is None:
             pubkeys, sig_list = self.get_siglist(txin, estimate_size)
-        add_w = lambda x: var_int(len(x) // 2) + x
             if txin['type'] in ['p2wpkh', 'p2wpkh-p2sh']:
-            witness = var_int(2) + add_w(sig_list[0]) + add_w(pubkeys[0])
+                witness = var_int(2) + witness_push(sig_list[0]) + witness_push(pubkeys[0])
             elif txin['type'] in ['p2wsh', 'p2wsh-p2sh']:
                 n = len(sig_list) + 2
                 witness_script = multisig_script(pubkeys, txin['num_sig'])
-            witness = var_int(n) + '00' + ''.join(add_w(x) for x in sig_list) + add_w(witness_script)
+                witness = var_int(n) + '00' + ''.join(witness_push(x) for x in sig_list) + witness_push(witness_script)
             else:
-            witness = txin.get('witness', None)
-            if not witness:
                 raise Exception('wrong txin type:', txin['type'])
         if self.is_txin_complete(txin) or estimate_size:
             value_field = ''
@@ -756,7 +765,7 @@ class Transaction:
 
     @classmethod
     def is_segwit_input(cls, txin):
-        has_nonzero_witness = txin.get('witness', '00') != '00'
+        has_nonzero_witness = txin.get('witness', '00') not in ('00', None)
         return cls.is_segwit_inputtype(txin['type']) or has_nonzero_witness
 
     @classmethod
@@ -768,6 +777,11 @@ class Transaction:
         _type = txin['type']
         if _type == 'coinbase':
             return txin['scriptSig']
+
+        script_sig = txin.get('scriptSig', None)
+        if script_sig is not None:
+            return script_sig
+
         pubkeys, sig_list = self.get_siglist(txin, estimate_size)
         script = ''.join(push_script(x) for x in sig_list)
         if _type == 'p2pk':
@@ -1035,7 +1049,8 @@ class Transaction:
                     sig = private_key.sign_digest_deterministic(pre_hash, hashfunc=hashlib.sha256, sigencode = ecdsa.util.sigencode_der)
                     if not public_key.verify_digest(sig, pre_hash, sigdecode = ecdsa.util.sigdecode_der):
                         raise Exception('Sanity check verifying our own signature failed.')
-                    txin['signatures'][j] = bh2u(sig) + '01'
+                    sig = bh2u(sig) + '01'
+                    self.add_signature_to_txin(txin, j, sig)
                     #txin['x_pubkeys'][j] = pubkey
                     txin['pubkeys'][j] = pubkey # needed for fd keys
                     self._inputs[i] = txin

plugins/digitalbitbox/digitalbitbox.py

@@ -643,7 +643,8 @@ class DigitalBitbox_KeyStore(Hardware_KeyStore):
                     sig_r = int(signed['sig'][:64], 16)
                     sig_s = int(signed['sig'][64:], 16)
                     sig = sigencode_der(sig_r, sig_s, generator_secp256k1.order())
-                    txin['signatures'][ii] = to_hexstr(sig) + '01'
+                    sig = to_hexstr(sig) + '01'
+                    Transaction.add_signature_to_txin(txin, ii, sig)
                     tx._inputs[i] = txin
         except UserCancelled:
             raise

plugins/ledger/ledger.py

@@ -498,7 +498,7 @@ class Ledger_KeyStore(Hardware_KeyStore):
 
         for i, txin in enumerate(tx.inputs()):
             signingPos = inputs[i][4]
-            txin['signatures'][signingPos] = bh2u(signatures[i])
+            Transaction.add_signature_to_txin(txin, signingPos, bh2u(signatures[i]))
         tx.raw = tx.serialize()
 
     @test_pin_unlocked