Encrypt-all should not touch already encrypted files

[PVince81]

Steps

1. Setup master key encryption
2. Run occ encryption:encrypt-all
3. Create a user "user1"
4. Login as that user
5. Upload some files
6. Log out
7. Decrypt the user's files occ encryption:decrypt-all user1
8. Change your mind and reencrypt: occ encryption:encrypt-all

Expected

A user argument for "encrypt-all" would be nice.
The second encryption pass only encrypts the files of user1 since the admin's files are already encrypted.

Actual

The process attempts to reencrypt already encrypted files from admin and fails:

Start to encrypt users files
----------------------------



 encrypt files for user admin (1): /admin/files/ownCloud Manual.pdf 
 [->--------------------------]
In Crypt.php line 483:
                 
  Bad Signature  
                 

encryption:encrypt-all

at this stage, none of the files of user1 are encrypted. I'd need to first decrypt everything then encrypt again.

Version

ownCloud 10.0.10 RC1

[sharidas]

Estimate: 1.5 md

[PVince81]

this is only about skipping already encrypted files

[sharidas]

master branch pr -> #61
stable10 branch pr -> owncloud/core#33206