[Owncloud] Encryption no longer working

[Andreas Heinlein]

Hello,

I have recently set up a private ownCloud instance and enabled the 
encryption app. This worked fine until I think the 4.0.3 update a few 
weeks ago. From then, all encrypted files which are downloaded contain 
merely random data; it looks like they're still encrypted. Unencrypted 
files (Images etc.) can be downloaded and viewed just fine. Updating to 
4.0.6 did not change anything. Password has not been changed since 
initial setup.

A file 'encryption.key' exists in /var/www/owncloud/data/<user> and is 
readable by the Apache user. Since I have come to the conclusion anyway 
that I no longer need the enryption app: is there any way to manually 
decrypt the files on the server?

Unfortunately, the encrypted files have also been sync'ed over the 
unencrypted ones on my desktop, so I have no clear copy of those files 
left. I have a backup of most of them, but not all.

Thanks for your help,
Andreas