Linux Encryption

[Ethos]

I've been spinning my wheels on how to use dm-crypt to fully encrypt a Ubuntu box(swap, root, and all). After going through several howtos I am as lost as ever, if anyone has any suggestions or can point me to a useful guide it would be very helpful. TIA

[Sitwon]

ftp://ftp.slackware.com/pub/slackware/slackware-current/README_CRYPT.TXT

[Ethos]

Thank you very much Sitwon. That how to has cleared up a lot of questions about dm-crypt and LUKS. by tonight I should have a Slackware version running with full disk encryption. =)

[Mr-Protocol]

It is kind of stupid to encrypt full disk on a linux system. All you really need to encrypt is /home/$USER

[Sitwon]

It is kind of stupid to encrypt full disk on a linux system. All you really need to encrypt is /home/$USER

Yes and no. It depends entirely on what you're trying to protect, who you're trying to protect it from, and what kinds of attacks you're worried about.

If you only encrypt your $HOME then someone with physical access could compromise your OS and thus compromise your $HOME the next time you login.

@Ethos: While that guide might have been written for Slackware, the same information is generally applicable to most other Linux distributions as well.

[Mr-Protocol]

If you only encrypt your $HOME then someone with physical access could compromise your OS and thus compromise your $HOME the next time you login.

No, even with the basic linux installer, the home directory is encrypted with your password. Also, you can just use a truecrypt volume for your home directory.

Infact, truecrypt doesn't even give the option for full disk encryption on linux because it's not needed.

[Sitwon]

No, even with the basic linux installer, the home directory is encrypted with your password. Also, you can just use a truecrypt volume for your home directory.

Infact, truecrypt doesn't even give the option for full disk encryption on linux because it's not needed.

Uh... No. Linux does encrypt your home directory by default. Some distributions, such as Ubuntu, give you the option to use something like EncFS at install-time, but it's not done by default. Nor is it common across distributions.

Furthermore, it doesn't matter which password it uses or what utility you use for encryption. If I have unencrypted access to everything outside your $HOME then I can replace any of the software on your system from the basic utilities to the program that decrypts your $HOME, I could even replace your whole kernel with a malicious one. Then it won't matter that your $HOME is encrypted on-disk because my malicious code is already in RAM and I can log your password or mess with your files when they're decrypted in memory.

If an attacker has unsupervised physical access to your machine and you don't have full-disk encryption then it's potentially compromised the next time you try to login. Period.

What I'm describing isn't that far fetched. It's actually just a less sophisticated version of the Evil Maid attack (google it). In theory the only thing that can protect you is hardware full-disk encryption (eg, with a TPM).