[Box Backup] out-of-the-blue CipherException?

Chris Wilson chris at qwirx.com
Thu Apr 12 09:12:08 BST 2012


Hi Matto,

On Wed, 11 Apr 2012, Matto Marjanovic wrote:

> ...and last night, I ran "check fix", figuring I had nothing to lose.
> It did its business, but the Cipher exception remained.  The "check fix"
> seems to have removed the 'spurious' refcount.db file, which caused a
> complaint when bbstored was started up again --- but it sounds like
> this may be old news to you.  (I must admit I have not looked through
> the trunk changelogs recently.)

Yeah, it's not supposed to be removed, bbstored will just recreate it next 
time it runs.

> I'll try that out -- it may take a couple of days to report back.

Thanks!

> In the meantime, could you perhaps elaborate on the nature of the 
> problem a bit more?  I got as far into the code as figuring out that 
> some sequence of encrypted filename records are sent from the server, 
> and then decrypted individually, and the decryption is exploding down in 
> openssl.  I had not yet figured out how the record stream is sent, nor 
> if the problem is truly in the client or if it could be bad data spit 
> out by the server.

The server has a filename stored on its disk, in one of the directory 
files, which the client can't decrypt. The client needs to decrypt all 
filenames in a directory on the server to know whether it needs to create 
a new one for a local file that didn't exist before, update an existing 
one keeping history, or delete one that no longer exists on the client.

The corruption might originally have happened on either the server or the 
client, probably while the directory was in memory a neutrino struck a RAM 
chip and flipped one of the bits, and the corrupted name was written back 
out to disk on the server.

Cheers, Chris.
-- 
_____ __     _
\  __/ / ,__(_)_  | Chris Wilson <chris+sig at qwirx.com> Cambs UK |
/ (_/ ,\/ _/ /_ \ | Security/C/C++/Java/Ruby/Perl/SQL Developer |
\__/_/_/_//_/___/ | We are GNU : free your mind & your software |



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