Date: Fri, 15 Jun 2012 17:43:50 -0400 From: Robert Simmons <rsimmons0@gmail.com> To: freebsd-security@freebsd.org Subject: Re: Pre-boot authentication / geli-aware bootcode Message-ID: <CA%2BQLa9BWHFibEFWp8uWySfmmqpLfOg2gT=S-pnmToV0XDz=eHw@mail.gmail.com> In-Reply-To: <CAC8HS2G9saUvZUcybnaBtC4hZ2pUunZP8JFdsg5skBHs=Yo20g@mail.gmail.com> References: <CA%2BQLa9Aec82k24YL46dU3zgbozTa8Qmis%2Bn14JpdZAemnaFZfw@mail.gmail.com> <CAC8HS2HW15VqfC09=c=nLJDewaOCNyRispide3jBnXnrZoYd6g@mail.gmail.com> <4FDB7AC4.3060709@argolis.org> <CAC8HS2G9saUvZUcybnaBtC4hZ2pUunZP8JFdsg5skBHs=Yo20g@mail.gmail.com>
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On Fri, Jun 15, 2012 at 5:24 PM, Simon L. B. Nielsen <simon@freebsd.org> wr= ote: > On Fri, Jun 15, 2012 at 7:11 PM, Matt Piechota <piechota@argolis.org> wro= te: >> On 06/15/2012 01:40 PM, Simon L. B. Nielsen wrote: >>> >>> On Jun 11, 2012 1:22 AM, "Robert Simmons"<rsimmons0@gmail.com> =A0wrote= : >>>> >>>> Would it be possible to make FreeBSD's bootcode aware of geli encrypte= d >>> >>> volumes? >>>> >>>> I would like to enter the password and begin decryption so that the >>>> kernel and /boot are inside the encrypted volume. =A0Ideally the only >>>> unencrypted area of the disk would be the gpt protected mbr and the >>>> bootcode. >>>> >>>> I know that Truecrypt is able to do something like this with its >>>> truecrypt boot loader, is something like this possible with FreeBSD >>>> without using Truecrypt? >>> >>> I just booted off a USB flash key. Then your entire drive can be >>> encrypted. >>> >> >> While true, the point (to me at least) is that with your kernel (and in >> Linux's case, initrd) in the clear it's possible for someone to bury a >> trojan of some sort in there waiting for you to boot up and start doing >> something nefarious (open backdoors, keylogging, etc.). I suppose you co= uld >> check hashes of the kernel stuff and whatnot on booting to see if they >> haven't been modified, but that's not fool-proof either. That's obviousl= y >> some pretty cloak and dagger stuff, but the company I work for requires = full >> disk encryption. I've never actually asked if /boot counts, somewhat fea= ring >> the answer and resulting hassle from the largely paper-pushing security >> types. > > If you are worried about somebody compromising the system with direct > access, you can't fix that if you are booting of it. Truecrypt does > not prevent somebody compromising the truecrypt loader from gaining > access to your system after you have supplied the compromised loader > with your password. > > 10 seconds of google searching: > http://theinvisiblethings.blogspot.ie/2009/10/evil-maid-goes-after-truecr= ypt.html > >> The USB key method isn't bad, but it realistically only adds obfuscation >> unless you keep your laptop and the key separate. Knowing myself, I'd fo= rget >> one or the other fairly often. :) > > I got a USB key which was ~1.2x2cm (from memory) so I just kept it in > my keychain, and it was only attached to a computer when the system > was booting (well, mostly) and when I had to upgrade kernel so I would > say it added more than obfuscation, but nothing is perfect. As I could > not get in at home without said keychain forgetting it wasn't really > much of a problem (or rather, more of a problem wrt. getting in than > wrt. booting laptop :-) ). > > It also provide a second factor'ish authentcation for the laptop as I > used GELI keyfiles on the USB key as part of the encryption key. > > Not saying it's perfect, but worked well for me (past tense as I don't > use a FreeBSD laptop anymore). > > Frankly I think there is a much simpler solution to this problem... if > you ever not loose access long enough to the laptop that somebody > could have done something funny, wipe drive and reinstall. It all > depends on your level of paranoia / requirements for security. > > PS. just because you are paranoid, doesn't mean they are not out to get y= ou :-). That article is a fascinating read. I like the idea of the Disk Hasher stick solution. Perhaps that idea could be made more secure if the hash stick itself was encrypted: http://www.imation.com/en-US/Mobile-Security/Mobile-Security-Products/Secur= e-Data/Imation-Flash-Drives-Powered-by-IronKey/Imation-Enterprise-S200-Flas= h-Drive-Powered-by-IronKey/ Along those lines, I wonder if a GPF Crypto Stick could be used to authenticate the geli decryption process rather than your insecure USB stick? http://www.privacyfoundation.de/crypto_stick/crypto_stick_english/
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