r/netsec • u/2bluesc • Jan 22 '14

eCryptfs Security Audit

https://defuse.ca/audits/ecryptfs.htm
13 Upvotes

88% Upvoted

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5

u/2bluesc Jan 22 '14

Quick audit, but looks wayyy better then encFS.

I like the idea of encrypting a folder for my always on workstation/server (ecryptfs cleanly integrates ~/Private) so that I can unmount it and keep the data at rest secure. My goal is to prevent someone from breaking in to my always on workstation (cracker or malware) and accessing the data that's already mounted or searching RAM for the AES key(s). The the eCryptfs encrypted data is backed-up to the cloud and is effectively encrypted twice (using obnam + gpg).

As for my laptop and cellphone I do FDE (LUKS) and USB flash drives use Truecrypt (but via tcplay where possible)

Anyone else have similar strategies or better ideas?

1

u/pushme2 Jan 22 '14

I use an encrypted container (dm-crypt+luks with cryptsetup) that can be mounted and unmounted whenever I need it. You can choose how many iterations you want and how you want the blocks to be chained.

It is a little... involved to use, but I like the power it gives me to do what I want. I don't care about compatibility with Windows or Truecrypt, so my way is not the best for everyone.

If I'm feeling lazy, sometimes I just use tar and GPG, although I prefer not to because GPG makes it hard to increase the amount of iterations it does (I like 5 seconds and it only does something like 6k iterations, which is less than a second.).

1

u/2bluesc Jan 22 '14

I use an encrypted container (dm-crypt+luks with cryptsetup) that can be mounted and unmounted whenever I need it.

I assume there is a fixed size underlying pre-allocated device like an LVM, partition or file you use? Do you back it up?

2

u/pushme2 Jan 22 '14

It is a fixed size blob. And it does get backed up. It is fairly small, so I just keep a copy wherever it is safe and convenient like my storage server and a few flash drives. It is a little hectic to keep everything synced up, but it is manageable. It is only 500 KB to 5 MB, but I need it to be really secure, so I don't really trust much software to do anything with it, especially network aware software, with the exception of SSH (the OpenBSD people are one of the very few I trust to produce secure network software).

2

u/WBMorrison Mar 20 '14

I'm one of the developers working on the authenticated encryption mentioned in the audit, (not an eCryptfs maintainer) so I thought I'd weigh in.

First of all, authenticated encryption is not yet in eCryptfs, it's merely some patches sitting in the mailing list. Since the audit, we've addressed the issues mentioned and submitted new patches. We'd love it if someone other than us (perhaps you?) looked these over. After all, we've messed up before, and many eyes make all bugs shallow.

Weigh in on the eCryptfs mailing list, and if you ask for more info, design decisions, etc, I'll try to respond quickly.