Type error when loading application

Information

• Python 2.7.6
• ledgerblue 1.1.16

Description

When loading an application on the ledger, I am seeing the following error:

Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/usr/local/lib/python2.7/dist-packages/ledgerblue/loadApp.py", line 174, in <module>
    loader.createApp(args.appFlags, appLength, args.appName, icon, path, None, None, args.appVersion)
  File "/usr/local/lib/python2.7/dist-packages/ledgerblue/hexLoader.py", line 163, in createApp
    data = self.encryptAES(data)
  File "/usr/local/lib/python2.7/dist-packages/ledgerblue/hexLoader.py", line 95, in encryptAES
    encryptedData = cipher.encrypt(paddedData)
  File "/usr/lib/python2.7/dist-packages/Crypto/Cipher/blockalgo.py", line 244, in encrypt
    return self._cipher.encrypt(plaintext)
TypeError: argument must be string or read-only buffer, not bytearray
make: *** [load] Error 1

This appears to be due to the change to hexLoader.py here https://github.com/LedgerHQ/blue-loader-python/commit/ed1e3a4dac54bbc3f0e6d0fa539199c889f92b6c for Python 3 compatibility, which unfortunately does not with python 2.7.x.

Version 0.1.15 works correctly and as intended.

Start in hexLoader.py at the Python 3 compatibility change referenced in the issue, then trace the encryptAES call from loadApp.py. Reproduce the failure with Python 2.7 and verify that loading an application works there while retaining Python 3 compatibility.