use base43 in order to send transactions by QR code

gui/qt/main_window.py

@@ -2240,8 +2240,8 @@ class ElectrumWindow(QMainWindow):
             return
         # else if the user scanned an offline signed tx
         # transactions are binary, but qrcode seems to return utf8...
-        import base64
-        z = base64.b64decode(data.decode('utf8'))
+        data = data.decode('utf8')
+        z = bitcoin.base_decode(data, length=None, base=43)
         data = ''.join(chr(ord(b)) for b in z).encode('hex')
         tx = self.tx_from_text(data)
         if not tx:

gui/qt/transaction_dialog.py

@@ -34,6 +34,7 @@ from PyQt4.QtCore import *
 import PyQt4.QtCore as QtCore
 
 from electrum import transaction
+from electrum.bitcoin import base_encode
 from electrum.plugins import run_hook
 
 from util import MyTreeWidget
@@ -108,9 +109,8 @@ class TxDialog(QDialog):
 
 
     def show_qr(self):
-        import base64
         text = self.tx.raw.decode('hex')
-        text = base64.b64encode(text)
+        text = base_encode(text, base=43)
         try:
             self.parent.show_qrcode(text, 'Transaction')
         except Exception as e: