Makes encryption optional.

jrnl.py

@@ -20,8 +20,12 @@ try: import simplejson as json
 except ImportError: import json
 import sys
 import readline, glob
+try:
     from Crypto.Cipher import AES
     from Crypto.Random import random, atfork
+    PYCRYPTO = True
+except ImportError: 
+    PYCRYPTO = False
 import hashlib
 import getpass
 try:
@@ -360,11 +364,15 @@ def setup():
     default_config['journal'] = os.path.expanduser(journal_path)
 
     # Encrypt it?
+    if PYCRYPTO:
         password = getpass.getpass("Enter password for journal (leave blank for no encryption): ")
         if password:
             default_config['encrypt'] = True
             print("Journal will be encrypted.")
             print("If you want to, you can store your password in .jrnl_config and will never be bothered about it again.")
+    else:
+        password = None
+        print("PyCrypto not found. To encrypt your journal, install the PyCrypto package from http://www.pycrypto.org and run 'jrnl --encrypt'. For now, your journal will be stored in plain text.")
 
     # Use highlighting:
     if not CLINT:
@@ -397,6 +405,11 @@ if __name__ == "__main__":
             with open(CONFIG_PATH, 'w') as f:
                 json.dump(config, f, indent=2)
 
+        # check if the configuration is supported by available modules
+        if config['encrypt'] and not PYCRYPTO:
+            print("According to your jrnl_conf, your journal is encrypted, however PyCrypto was not found. To open your journal, install the PyCrypto package from http://www.pycrypto.org.")
+            sys.exit(-1)
+
     parser = argparse.ArgumentParser()
     composing = parser.add_argument_group('Composing', 'Will make an entry out of whatever follows as arguments')
     composing.add_argument('-date', dest='date', help='Date, e.g. "yesterday at 5pm"')
@@ -487,6 +500,9 @@ if __name__ == "__main__":
     elif args.markdown: # export to json
         print(journal.to_md())
 
+    elif (args.encrypt or args.decrypt) and not PYCRYPTO:
+        print("PyCrypto not found. To encrypt or decrypt your journal, install the PyCrypto package from http://www.pycrypto.org.")
+
     # Encrypt into new file If args.encrypt is True, that it is present in the command line arguments
     # but isn't followed by any value - in which case we encrypt the journal file itself. Otherwise
     # encrypt to a new file.