First of all let me thank you for a great tool that you have created. I have started using it and have noticed a couple of features that may be useful.
Foremost I would like to see a password verification on decryption. This would be needed since I inadvertently ran into a scenario that can cause issues. After having done a few hours of work and around 2am I wanted to test the encryption, so I came up with a password and encrypted my work. Surfed the net for a few minutes and then tried to decrypt the files which only produced garbage files to my dismay. Next I encrypted a few files and decrypted them again and of course it worked just fine.
To test and see what I had done wrong I encrypted the same files again and tried decrypting them again with a wrong password. Well the program accepted the wrong password and in effect ended up double encrypting the files.
Now there are 2 circumstances that this can cause issues for a user, one that they have forgotten their password and try from a set of passwords that they might have tried. However after the first try the correct password will not produce a desired result any more. The second circumstance is even worse where a malicious user attempts at guessing the password a few times would fail and give up, however the users files are now completely irretrievable.
The second thing that I would like to see would be a finer control over the folders and extensions that get encrypted, just like the backup and sync methods.
Once more thanks for your great tool.