bitcoin.py/transaction.py: API changes: rm most hex usage

Instead of some functions operating with hex strings,
and others using bytes, this consolidates most things to use bytes.

This mainly focuses on bitcoin.py and transaction.py,
and then adapts the API usages in other files.

Notably,
- scripts,
- pubkeys,
- signatures
should be bytes in almost all places now.

electrum/submarine_swaps.py

@@ -12,8 +12,8 @@ import aiohttp
 from . import lnutil
 from .crypto import sha256, hash_160
 from .ecc import ECPrivkey
-from .bitcoin import (script_to_p2wsh, opcodes, p2wsh_nested_script, push_script,
-                      is_segwit_address, construct_witness)
+from .bitcoin import (script_to_p2wsh, opcodes,
+                      construct_witness)
 from .transaction import PartialTxInput, PartialTxOutput, PartialTransaction, Transaction, TxInput, TxOutpoint
 from .transaction import script_GetOp, match_script_against_template, OPPushDataGeneric, OPPushDataPubkey
 from .util import log_exceptions, BelowDustLimit, OldTaskGroup
@@ -87,18 +87,17 @@ WITNESS_TEMPLATE_REVERSE_SWAP = [
 
 def check_reverse_redeem_script(
     *,
-    redeem_script: str,
+    redeem_script: bytes,
     lockup_address: str,
     payment_hash: bytes,
     locktime: int,
     refund_pubkey: bytes = None,
     claim_pubkey: bytes = None,
 ) -> None:
-    redeem_script = bytes.fromhex(redeem_script)
     parsed_script = [x for x in script_GetOp(redeem_script)]
     if not match_script_against_template(redeem_script, WITNESS_TEMPLATE_REVERSE_SWAP):
         raise Exception("rswap check failed: scriptcode does not match template")
-    if script_to_p2wsh(redeem_script.hex()) != lockup_address:
+    if script_to_p2wsh(redeem_script) != lockup_address:
         raise Exception("rswap check failed: inconsistent scriptcode and address")
     if ripemd(payment_hash) != parsed_script[5][1]:
         raise Exception("rswap check failed: our preimage not in script")
@@ -438,7 +437,7 @@ class SwapManager(Logger):
 
     def add_normal_swap(
             self, *,
-            redeem_script: str,
+            redeem_script: bytes,
             locktime: int,  # onchain
             onchain_amount_sat: int,
             lightning_amount_sat: int,
@@ -487,7 +486,7 @@ class SwapManager(Logger):
         lockup_address = script_to_p2wsh(redeem_script)
         receive_address = self.wallet.get_receiving_address()
         swap = SwapData(
-            redeem_script = bytes.fromhex(redeem_script),
+            redeem_script=redeem_script,
             locktime = locktime,
             privkey = our_privkey,
             preimage = None,
@@ -533,7 +532,7 @@ class SwapManager(Logger):
     def add_reverse_swap(
         self,
         *,
-        redeem_script: str,
+        redeem_script: bytes,
         locktime: int,  # onchain
         privkey: bytes,
         lightning_amount_sat: int,
@@ -545,7 +544,7 @@ class SwapManager(Logger):
         lockup_address = script_to_p2wsh(redeem_script)
         receive_address = self.wallet.get_receiving_address()
         swap = SwapData(
-            redeem_script = bytes.fromhex(redeem_script),
+            redeem_script = redeem_script,
             locktime = locktime,
             privkey = privkey,
             preimage = preimage,
@@ -645,7 +644,7 @@ class SwapManager(Logger):
         onchain_amount = data["expectedAmount"]
         locktime = data["timeoutBlockHeight"]
         lockup_address = data["address"]
-        redeem_script = data["redeemScript"]
+        redeem_script = bytes.fromhex(data["redeemScript"])
         # verify redeem_script is built with our pubkey and preimage
         check_reverse_redeem_script(
             redeem_script=redeem_script,
@@ -805,7 +804,7 @@ class SwapManager(Logger):
         invoice = data['invoice']
         fee_invoice = data.get('minerFeeInvoice')
         lockup_address = data['lockupAddress']
-        redeem_script = data['redeemScript']
+        redeem_script = bytes.fromhex(data['redeemScript'])
         locktime = data['timeoutBlockHeight']
         onchain_amount = data["onchainAmount"]
         response_id = data['id']
@@ -1052,7 +1051,7 @@ class SwapManager(Logger):
         txin.witness_script = witness_script
         sig_dummy = b'\x00' * 71  # DER-encoded ECDSA sig, with low S and low R
         witness = [sig_dummy, preimage, witness_script]
-        txin.witness_sizehint = len(bytes.fromhex(construct_witness(witness)))
+        txin.witness_sizehint = len(construct_witness(witness))
 
     @classmethod
     def sign_tx(cls, tx: PartialTransaction, swap: SwapData) -> None:
@@ -1063,9 +1062,9 @@ class SwapManager(Logger):
         assert txin.prevout.txid.hex() == swap.funding_txid
         txin.script_sig = b''
         txin.witness_script = witness_script
-        sig = bytes.fromhex(tx.sign_txin(0, swap.privkey))
+        sig = tx.sign_txin(0, swap.privkey)
         witness = [sig, preimage, witness_script]
-        txin.witness = bytes.fromhex(construct_witness(witness))
+        txin.witness = construct_witness(witness)
 
     @classmethod
     def _create_and_sign_claim_tx(