Starting on Version 7.0 using the work done by others. Completely untested. I will be testing things, but I thought I'd get this base version up for others to give pull requests.

THIS IS ON THE MASTER BRANCH. The Master branch will be Python 3.0 from now on. While Python 2.7 support will not be deliberately broken, all efforts should now focus on Python 3.0 compatibility.

I can see a lot of work has been done. There's more to do. I've bumped the version number of everything I came across to the next major number for Python 3.0 compatibility indication.

Thanks everyone. I hope to update here at least once a week until we have a stable 7.0 release for calibre 5.0

DeDRM_plugin/ignoblekeyfetch.py

@@ -2,9 +2,10 @@
 # -*- coding: utf-8 -*-
 
 from __future__ import with_statement
+from __future__ import print_function
 
-# ignoblekeyfetch.pyw, version 1.1
-# Copyright © 2015 Apprentice Harper
+# ignoblekeyfetch.pyw, version 2.0
+# Copyright © 2015-2020 Apprentice Harper et al.
 
 # Released under the terms of the GNU General Public Licence, version 3
 # <http://www.gnu.org/licenses/>
@@ -24,11 +25,11 @@ from __future__ import with_statement
 # Revision history:
 #   1.0 - Initial  version
 #   1.1 - Try second URL if first one fails
+#   2.0 - Added Python 3 compatibility for calibre 5.0
 
 """
 Fetch Barnes & Noble EPUB user key from B&N servers using email and password
 """
-from __future__ import print_function
 
 __license__ = 'GPL v3'
 __version__ = "1.1"
@@ -46,7 +47,7 @@ class SafeUnbuffered:
         if self.encoding == None:
             self.encoding = "utf-8"
     def write(self, data):
-        if isinstance(data,unicode):
+        if isinstance(data,bytes):
             data = data.encode(self.encoding,"replace")
         self.stream.write(data)
         self.stream.flush()
@@ -87,7 +88,7 @@ def unicode_argv():
             # Remove Python executable and commands if present
             start = argc.value - len(sys.argv)
             return [argv[i] for i in
-                    xrange(start, argc.value)]
+                    range(start, argc.value)]
         # if we don't have any arguments at all, just pass back script name
         # this should never happen
         return [u"ignoblekeyfetch.py"]
@@ -95,7 +96,7 @@ def unicode_argv():
         argvencoding = sys.stdin.encoding
         if argvencoding == None:
             argvencoding = "utf-8"
-        return [arg if (type(arg) == unicode) else unicode(arg,argvencoding) for arg in sys.argv]
+        return argv
 
 
 class IGNOBLEError(Exception):
@@ -103,9 +104,9 @@ class IGNOBLEError(Exception):
 
 def fetch_key(email, password):
     # change email and password to utf-8 if unicode
-    if type(email)==unicode:
+    if type(email)==bytes:
         email = email.encode('utf-8')
-    if type(password)==unicode:
+    if type(password)==bytes:
         password = password.encode('utf-8')
 
     import random
@@ -236,7 +237,7 @@ def gui_main():
             self.status['text'] = u"Fetching..."
             try:
                 userkey = fetch_key(email, password)
-            except Exception, e:
+            except Exception as e:
                 self.status['text'] = u"Error: {0}".format(e.args[0])
                 return
             if len(userkey) == 28: