cache xpub values in account in order to generate addresses faster

lib/account.py

@@ -164,7 +164,6 @@ class ImportedAccount(Account):
     def get_name(self, k):
         return _('Imported keys')
 
-
     def update_password(self, old_password, new_password):
         for k, v in self.keypairs.items():
             pubkey, a = v
@@ -280,6 +279,8 @@ class BIP32_Account(Account):
     def __init__(self, v):
         Account.__init__(self, v)
         self.xpub = v['xpub']
+        self.xpub_receive = None
+        self.xpub_change = None
 
     def dump(self):
         d = Account.dump(self)
@@ -308,7 +309,17 @@ class BIP32_Account(Account):
         return pubkeys[i]
 
     def derive_pubkeys(self, for_change, n):
-        return self.derive_pubkey_from_xpub(self.xpub, for_change, n)
+        xpub = self.xpub_change if for_change else self.xpub_receive
+        if xpub is None:
+            xpub = bip32_public_derivation(self.xpub, "", "/%d"%for_change)
+            if for_change:
+                self.xpub_change = xpub
+            else:
+                self.xpub_receive = xpub
+        _, _, _, c, cK = deserialize_xkey(xpub)
+        cK, c = CKD_pub(cK, c, n)
+        result = cK.encode('hex')
+        return result
 
 
     def get_private_key(self, sequence, wallet, password):
@@ -348,18 +359,9 @@ class BIP32_Account(Account):
         assert len(s) == 2
         return xkey, s
 
-
     def get_name(self, k):
-        name = "Unnamed account"
-        m = re.match("m/(\d+)'", k)
-        if m:
-            num = m.group(1)
-            if num == '0':
-                name = "Main account"
-            else:
-                name = "Account %s"%num
-                    
-        return name
+        return "Main account" if k == '0' else "Account " + k
+