[ZendTo] manually retrieve an encrypted file?

Jules Field Jules at Zend.To
Thu Oct 18 15:32:18 BST 2018


I have seen 1 other instance of this. It appears to be caused by the 
encryption process failing. Take a look in the Apache logs and let me 
know what error message you see in the error_log. I need to improve the 
checking of values read from the header I add to the encrypted file, to 
ensure that things like the hashing and encryption algorithm names are 
valid before I try to use them.

I haven't managed to reproduce this problem myself, but I'm pretty sure 
this is what is happening. By the time I come to decrypt the data, if 
it's damaged by that point then I can't retrieve it, but I can flag the 
error a lot better than currently!

One thing to try: given the ClaimID look in the /var/zendto/dropoffs 
directory for the files that belong to that ClaimID. The filenames will 
be random, and each file should be a bit longer than the original 
version uploaded. See if you can work out which one is the problem file. 
Is that file actually encrypted *at all*? The "file" command will help 
you here. Do a "file *" in the relevant dropoff directory, and it 
*should* say something like they are all just "data". If it identifies 
one as a Word document, zip file, PDF file anything like that, then the 
file didn't get encrypted for some reason.

If that is the case, please can you look back through your zendto.log 
file (either in /var/zendto or /var/log/zendto) to see if anything odd 
happened when the drop-off was originally uploaded.

Please can you let me know what you find?

Also, I am going to write you a command-line utility so retrieve the 
files from a drop-off given the claim ID and the passphrase. It will 
probably just write all the files with their original names into the 
current directory. Even for unencrypted drop-offs, it would still be a 
useful tool. I'll make it prompt for the passphrase if one is needed 
(i.e. if the drop-off is encrypted).


On 12/10/2018 15:28, MICHAEL R MASSE via ZendTo wrote:
> Is there a way as the administrator of the system hosting my Zendto 
> service that I can decrypt a file that’s been uploaded if I have the 
> passphrase?  I have direct access to the sqlite database to get the 
> key as well, but I’m not sure what to do with either.
> I’m running 5.15-1 and the system works fine except one single user is 
> trying to receive a file from someone outside of the system and when 
> they try to download this specific file after typing in the passphrase 
> they just get a http 500 error.    The sender does not receive any 
> errors when uploading.   It actually doesn’t matter if the recipient 
> types a correct passphrase or not, they always get an http 500 error 
> on this particular file.    As an administrator if I try to download 
> the file and regardless of the passphrase I enter (correct or not) I 
> get an http 500 error as well.  This does not happen for anyone else 
> for any other files in the system sent before or after.    Also, for 
> every other file on the system, if an incorrect passphrase is used, 
> the system says it’s incorrect like it should instead of giving an 
> http 500 error.   I told the person to have their sender send the file 
> again, and it again throws an http 500 error.    It’s only a 2mb file 
> so there’s nothing weird about it.    After telling them to upload the 
> file twice and having it fail I’d like to just decrypt the file that’s 
> there and manually give it to the recipient since he’s local, and then 
> worry about troubleshooting the problem later.
> -Mike
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'What happened in the past that was painful, has a great deal to
  do with what we are today.' - William Glasser

Twitter: @JulesFM

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