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Authenticated Boot and Disk Encryption on Linux

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Re: Authenticated Boot and Disk Encryption on Linux

#121

Post by miloignis »

LeifCarrotson wrote: post #43
remuskaos wrote: post #38

Earlier quoted context omitted.

That's what those countless convention stickers are for, they're basically a cryptographic hash of all the leet stuff you've attended.

This or the 'glitter nail-polish' pseudo-holographic identifiers both ignore that if you have a physically identical laptop save cosmetics, you can swap in the motherboard and hard disk from the replacement unit. Externally, it's identical, internally it's all compromised.

If you put the nail polish on the screws or seams, you could make it where you couldn't take apart the laptop to replace the motherboard without damaging them, right?

Re: Authenticated Boot and Disk Encryption on Linux

#122

Post by dane-pgp »

LeifCarrotson wrote: post #43
remuskaos wrote: post #38

Earlier quoted context omitted.

That's what those countless convention stickers are for, they're basically a cryptographic hash of all the leet stuff you've attended.

This or the 'glitter nail-polish' pseudo-holographic identifiers both ignore that if you have a physically identical laptop save cosmetics, you can swap in the motherboard and hard disk from the replacement unit. Externally, it's identical, internally it's all compromised.

Presumably the laptop could be designed such that opening the case would separate some contacts in a circuit, which in turn would clear some important secret value from memory.

If you have a separate authentication device, it could warn you that this had happened, to prevent the attack of someone opening the case to add a circuit which broadcasts your key presses, for example.

This still only reduces the problem from keeping your laptop with you at all times to keeping your authentication device with you at all times, though.

Re: Authenticated Boot and Disk Encryption on Linux

#123

Post by JonathonW »

yyyk wrote: post #99

This is a thoughtful post, yet it is useful to think again about the threat scenarios. Poettering mentions three: The obvious 'basic' one, and two advanced scenarios focused on a thief stealing the computer and then returning it. I recall exactly one case close to the these latter two scenarios: When Mossad stole a Syrian laptop allegedly containing nuclear weapon program information and returned it[0]. However, I do…

> In return, we get more complexity by splitting the system into at least three components*, and going back into the partitioning mess ("You only gave 300GB to /home, in order to download the ISO you want you need to repartition the system").

Is there anything akin to APFS containers [1] in the Linux space? APFS's ability to share space between multiple filesystems is, among other features, how Apple is able to get away with splitting the filesystem up similarly to Poettering's proposal. (They don't go quite as far; they have a signed, sealed system volume plus a single user volume rather than Poettering's multiple user volumes, but the split is still there and therefore runs into the same issue of space allocation.)

[1] https://en.wikipedia.org/wiki/Apple_File_System#Partition_sc...

Re: Authenticated Boot and Disk Encryption on Linux

#124

Post by HanaShiratori »

teddyh wrote: post #111

If your attacker is both sophisticated and able to access your hardware directly, the game is over; nothing we can do can currently avoid this. What we can do is address the scenarios in which an attacker is either unsophisticated or remote . Normal network security takes care of the latter case, and for unsophisticated attackers, a good FDE (Full Disk Encryption) system covers it nicely. For laptops you can either l…

Wait, did I miss something or how does a sophisticated attacker break encryption with ~100+ bit password entropy?

Re: Authenticated Boot and Disk Encryption on Linux

#125

Post by cmurf »

A keylogger in the initramfs seems like a pretty obvious weakness to try and exploit. From there the attacker eventually gets the password manager master password, as well as any disk encryption passwords.

We could soon get to signed grub being able to read and authenticate from as fs-verity /boot on which initrd resides. Ext4 and recently btrfs support fs-verity and its more flexible than dm-verity.

Re: Authenticated Boot and Disk Encryption on Linux

#126

Post by [deleted] »

teddyh wrote: post #111

If your attacker is both sophisticated and able to access your hardware directly, the game is over; nothing we can do can currently avoid this. What we can do is address the scenarios in which an attacker is either unsophisticated or remote . Normal network security takes care of the latter case, and for unsophisticated attackers, a good FDE (Full Disk Encryption) system covers it nicely. For laptops you can either l…

[deleted]

Re: Authenticated Boot and Disk Encryption on Linux

#127

Post by xvedejas »

gear54rus wrote: post #119
teddyh wrote: post #111

If your attacker is both sophisticated and able to access your hardware directly, the game is over; nothing we can do can currently avoid this. What we can do is address the scenarios in which an attacker is either unsophisticated or remote . Normal network security takes care of the latter case, and for unsophisticated attackers, a good FDE (Full Disk Encryption) system covers it nicely. For laptops you can either l…

How does one go about breaking FDE tho? If it's secured by a password that's only in your mind.

Keylogging? Depending on the bar for sophistication, I'm told this could be done by a microphone at the other end of town, or by measuring the power consumption of your building from the grid... but there's probably something at the middle point between these paranoid risks and something simple anyone could place in your computer case / keyboard.

Re: Authenticated Boot and Disk Encryption on Linux

#128

Post by droopyEyelids »

HanaShiratori wrote: post #124
teddyh wrote: post #111

If your attacker is both sophisticated and able to access your hardware directly, the game is over; nothing we can do can currently avoid this. What we can do is address the scenarios in which an attacker is either unsophisticated or remote . Normal network security takes care of the latter case, and for unsophisticated attackers, a good FDE (Full Disk Encryption) system covers it nicely. For laptops you can either l…

Wait, did I miss something or how does a sophisticated attacker break encryption with ~100+ bit password entropy?

if they have access to your device, they don't have to. They'll just snoop on whatever you use to enter your key.

Re: Authenticated Boot and Disk Encryption on Linux

#129

Post by BiteCode_dev »

theandrewbailey wrote: post #61
BiteCode_dev wrote: post #14

Are other people experiencing too many corruption problems on encrypted disks? I have a veracrypt drive, and I regularly have to run a scan and fix on it because it's very sensitive to power cut, brutal restart, etc. Also, it's slow. I put my firefox conf folder in it, but it slows the browser down. Once I went full encrypted disk, but one day corruption happened, and it stopped booting. So I went back.

No. I run a server in my basement, and for the past 5+ years, every one of its drives have been LUKS encrypted, including external backup drives. I've had no issues with encryption (corruption, speed, or otherwise), only disk hardware failing outright.

Servers and consumer laptop are very different beast though, so not sure the comparison hold. You don't shut them off often, they don't go to sleep, rarely undergo shock, plane travel or forced shut down...

Re: Authenticated Boot and Disk Encryption on Linux

#130

Post by colek42 »

teddyh wrote: post #111

If your attacker is both sophisticated and able to access your hardware directly, the game is over; nothing we can do can currently avoid this. What we can do is address the scenarios in which an attacker is either unsophisticated or remote . Normal network security takes care of the latter case, and for unsophisticated attackers, a good FDE (Full Disk Encryption) system covers it nicely. For laptops you can either l…

The issue isn't compromise of the remote system, but trust of that remote system. TPM 2.0 gives us the ability to make measurements before establishing trust.
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