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WTF is a KDF?

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Re: WTF is a KDF?

#21

Post by Gasp0de »

WastingMyTime89 wrote: post #10
t0mas88 wrote: post #9

Earlier quoted context omitted.

Even with the smallest instance types that's around 8 million in compute cost. Doesn't sound like something you would spend on a small crime?

Multiple possible scenarios: - He actually gave his password himself as part of a deal with the police which includes this as a cover up. - The police got his password through another mean they don’t want to disclose and are using this as a cover up. - They really want a list of his contacts and what they were discussing because they are scared than one of them could be tempted to do more than burn a few cars. - Fran…

Bitlocker also saves encryption backup keys in the Microsoft cloud where they can probably subpoenad? Then they might have found the password saved on the windows PC somewhere.

Re: WTF is a KDF?

#22

Post by Gasp0de »

I think the most likely situation is this:

Bitlocker can save backup keys in the cloud where they can probably be subpoenad by the police. If the victim used a password manager without encryption (e.g. browser) and used or saved the same password somewhere else, they might have gotten it this way.

Re: WTF is a KDF?

#23

Post by doodlesdev »

TacticalCoder wrote: post #15

What I find weird is that not many talk about one of the parameter to PBKDF2, c , the number of iterations desired. Someone here mentioned it a few days ago: just make decryption fast enough to be acceptable for you but still a big multiplier compared to the default. What do people care, when unlocking their SSD, if it takes 3ms or 300ms to unlock the SSD at boot? I mean: attacker shall have a bazillion RAM and a tri…

The problem is PBKDF2 isn't as memory intensive, it's really easy to parallelize on a modern GPU thus making it a much worse PBKDF than Argon2id. Increasing iteration count is just a bandaid over this problem, you also need to have control over memory usage.

Re: WTF is a KDF?

#24

Post by hh3k0 »

Gasp0de wrote: post #22

I think the most likely situation is this: Bitlocker can save backup keys in the cloud where they can probably be subpoenad by the police. If the victim used a password manager without encryption (e.g. browser) and used or saved the same password somewhere else, they might have gotten it this way.

I might be wrong, but something tells me that people who use LUKS to encrypt a hard drive would not use the password in question for an online service.

Re: WTF is a KDF?

#25

Post by vladvasiliu »

adriancr wrote: post #19
dist-epoch wrote: post #12

Compared to Windows+Bitlocker, using full disk encryption on Ubuntu (the most user friendly distro) is bizarrely difficult. By default the boot partition is not encrypted (so evil maid attacks are easier) and the KDF iteration counts are way too low, as can be seen here. When I setup FDE with LUKS on my Ubuntu laptop I had to go the manual route since I noticed that the default iteration counts don't make any sense,…

Even if you encrypt boot partition someone could modify grub to grab password for boot partition used there. Then with that password they can evil maid again and change your boot partition. (unless you have same password on root/boot or password is embedded in boot partition in which case win for attacker) You could detect evil maid if you add a script that does a hash over grub used to load with a salt from boot sec…

You can use an unencrypted /boot and have UEFI boot a unified kernel image with the kernel command line built in. And have secure boot verify the signature of that image.

A TPM could possibly be helpful: you can't be sure that the PC you're booting up is actually yours and not a clone or has somehow had secure boot disabled that's booting a tampered kernel image. So if the TPM usually unlocks your drive (and a PIN, for added security) and it suddenly asks for your password, then something could be going on.

Re: WTF is a KDF?

#26

Post by jeroenhd »

Gasp0de wrote: post #22

I think the most likely situation is this: Bitlocker can save backup keys in the cloud where they can probably be subpoenad by the police. If the victim used a password manager without encryption (e.g. browser) and used or saved the same password somewhere else, they might have gotten it this way.

Bitlocker saves the recovery key to the cloud, not the unlock PIN. Both can be used to recover access to the data, but the recovery key is not directly related to the password chosen.

Furthermore, the article talks about LUKS, which is decidedly not related to Bitlocker.

I doubt they would've spent the ridiculous amount of money you need to crack LUKS though. Most likely, the password was a phrase that could be brute forced through a dictionary attack, or it was reused somewhere else.

That's not to say we shouldn't move to Argon2i as GPU performance increases over time. Argon is proven to be stronger and there's very little reason not to upgrade if you can get your bootloader to unlock the modern LUKS standard (i.e. not GRUB).

Re: WTF is a KDF?

#27

Post by marginalia_nu »

WastingMyTime89 wrote: post #10
t0mas88 wrote: post #9

Earlier quoted context omitted.

Even with the smallest instance types that's around 8 million in compute cost. Doesn't sound like something you would spend on a small crime?

Multiple possible scenarios: - He actually gave his password himself as part of a deal with the police which includes this as a cover up. - The police got his password through another mean they don’t want to disclose and are using this as a cover up. - They really want a list of his contacts and what they were discussing because they are scared than one of them could be tempted to do more than burn a few cars. - Fran…

If I wanted to get at an encrypted hard drive, I'd just tamper with the keyboard and record the password as it was being typed. Hardware keyloggers can be made very tiny with resources and determination.

Re: WTF is a KDF?

#28

Post by jeroenhd »

mr_mitm wrote: post #13

It really annoys me how everyone takes that statement that a 20 character password has been cracked at face value. If it was randomly generated, it is physically impossible to crack even if it was hashed with MD5. It's also unlikely that somebody memorized 20 random characters. It is much more likely that the passphrase was weak because it's the title of a Wikipedia article or contained in some public word list. Also…

Until we know his password, we can't know for certain. "Fuck the police!2023" fits the description of the password but it's hardly unguessable.

All we know is the authorities gained access to his drive's key. We probably won't find out how they did it until his trial starts.

Re: WTF is a KDF?

#29

Post by dist-epoch »

mr_mitm wrote: post #13

It really annoys me how everyone takes that statement that a 20 character password has been cracked at face value. If it was randomly generated, it is physically impossible to crack even if it was hashed with MD5. It's also unlikely that somebody memorized 20 random characters. It is much more likely that the passphrase was weak because it's the title of a Wikipedia article or contained in some public word list. Also…

Why would they do an evil maid attack on the Ubuntu laptop, but not at the same time on the Windows one?

And is there any information that they accessed the Ubuntu laptop before he was arrested (to do the evil maid attack)? I see no mention of that.

I think it's much more likely that it was a weak password, maybe even partially shared with other passwords. Maybe police obtained user passwords from other low value targets (online shops, ...), looked at them and noticed a pattern.

> There are even files that had been deleted and emails that had been downloaded with Thunderbird (and then deleted).

This doesn't mean much, unless user didn't know that when you delete a file it's content is not actually scrubbed from storage.

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