bip32: refactor whole module. clean-up.

electrum/plugins/coldcard/coldcard.py

@@ -6,7 +6,7 @@ from struct import pack, unpack
 import os, sys, time, io
 import traceback
 
-from electrum.bip32 import serialize_xpub, deserialize_xpub, InvalidMasterKeyVersionBytes
+from electrum.bip32 import BIP32Node, InvalidMasterKeyVersionBytes
 from electrum.i18n import _
 from electrum.plugin import Device
 from electrum.keystore import Hardware_KeyStore, xpubkey_to_pubkey, Xpub
@@ -40,12 +40,7 @@ try:
         def mitm_verify(self, sig, expect_xpub):
             # verify a signature (65 bytes) over the session key, using the master bip32 node
             # - customized to use specific EC library of Electrum.
-            from electrum.ecc import ECPubkey
-
-            xtype, depth, parent_fingerprint, child_number, chain_code, K_or_k \
-                = deserialize_xpub(expect_xpub)
-
-            pubkey = ECPubkey(K_or_k)
+            pubkey = BIP32Node.from_xkey(expect_xpub).eckey
             try:
                 pubkey.verify_message_hash(sig[1:65], self.session_key)
                 return True
@@ -191,12 +186,12 @@ class CKCCClient:
         # TODO handle timeout?
         # change type of xpub to the requested type
         try:
-            __, depth, fingerprint, child_number, c, cK = deserialize_xpub(xpub)
+            node = BIP32Node.from_xkey(xpub)
         except InvalidMasterKeyVersionBytes:
             raise UserFacingException(_('Invalid xpub magic. Make sure your {} device is set to the correct chain.')
                                       .format(self.device)) from None
         if xtype != 'standard':
-            xpub = serialize_xpub(xtype, c, cK, depth, fingerprint, child_number)
+            xpub = node._replace(xtype=xtype).to_xpub()
         return xpub
 
     def ping_check(self):