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I'm getting a netbook today, and I intend to dual boot Ubuntu and XP in it while encrypting the hard drive for obvious reasons. Problem is: I know that encrypting the entire harddrive in a dualboot system is gonna give me headaches, so I'm just gonna encrypt my /home partition in Ubuntu (which is going to be the main OS). And that leads to my question:

Is that enough to protect my personal data? Does ubuntu store any kind of personal data whatsoever outside of /home?

I hope I've been clear enough. Thanks.

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up vote 5 down vote accepted

There shouldn't be any personal data outside the /home directory that a reasonable person would be bothered about.

It is however possible that a rubbish application developer has, at some stage, decided to keep some files that you would want to have included in your encrypted partition somewhere else, and that nobody has ever picked up on it.

Whether encrypting your /home is enough depends on how paranoid you are. For example, consider encrypting your swap as it contains straight dumps of memory and is not normally wiped after use, so could be read by some recovery tools. But if someone gets hold of your machine how likely are they to start trying such things? If you are Barack Obama and Chinese spies get your computer, you may have a problem, but if it contains the novel you are writing and is stolen by some druggies after selling it for a fix, you probably don't have too much to worry about.

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Indeed, I'm not realyl worried about stuff like cold-boot attacks or swap wiping. I just wanted to encrypt my personal files to make sure that they're not as easy to access as "boot up a liveCD and copy". – Malabarba Jan 26 '10 at 15:39

There is is mail in /var/mail and personal crontabs in /var/lib/crontab, both probably rarely in use on personal computers. Then there are log files in /var/log which detail what you did on the machine, so could be considered personal data, and things like /var/cache/samba and /var/lib/samba which contains things like printer spools. Also, /etc could contain network passwords in various locations. And so on, and so on.

Short answer, I wouldn't do it. Just encrypt the entire disk and have less worries.

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+1 better than mine. Also you missed the /tmp too. – whitequark Jan 26 '10 at 16:00

Consider that a lot of stuff you may not want outsiders to find may show up in /tmp.

If I were you, I would follow Peter Eisentraut's suggestion and encrypt the whole drive.

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At the risk of sounding trollish, I'd like to point that the "for obvious reasons" in your question sounds funny for some people and scary for another people. A potential reader of your question would almost certainly replace this "for obvious reasons" with some of his hidden fears or assumptions that are not backed up by any facts. For example "this can be an alien"/"this can be a spy"/"this can be a terrorist"/"this can be a pedophile"/[insert your favorite here]. That potential reader instantly doesn't trust you anymore and you'll miss a chance to get an answer from him.

But this is psychology. Let's go back to the technical part.

Bruce Schneier, a security guru, said: "Security is a process". These are not just some wise words that sound cool and make you look smarter when you say them to other people. This is an important general criterion that you shall apply to any situation involving security.

So let's talk about your situation. Let's say you have a fully encrypted hard drive and you use a strong encryption key. Are you safe? It depends. Because this is a static situation. And a process is continuous, not static. Does your computer connect to the internet? If so, you've got a lot of new factors to consider. You have personal mail stored on your encrypted hard drive? Yes? Ok. It is relatively safe there. You've got it via pop3/imap from a server and you didn't use an encrypted connection? Well, here you fail. Somebody could have been sniffed it and doesn't need to break into your encrypted hard drive. You used SSL when downloading mail, but the mail server doesn't use an encrypted storage for storing mail? Well, theoretically you have problems again. Because the mail server is the weakest point now and a potential attacker will try to go for it instead of going for your encrypted hard drive if he wants to get at you.

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