Encrypting your hard drive (for noobs)

[zahc]

I installed a virtualbox linux at work, because while I can use Windows if forced, I can't be WITHOUT linux. I mean, what if I want to do something? Anyway, the latest Ubuntu (which I have never successfully installed before) asked me if I wanted to encrypt my home partition, and since I had nothing to lose, I said yes. And that was it. Nothing else happened. I just logged in as normal when I rebooted after the install. So I am quite confused about what actually happened.

After I logged in, the system helpfully told me that I could view my encryption passcode now, or do it later by running $somelongcommand and entering my password. I ran $somelongcommand, entered my password and got this giant thing like this: 8872f92xas2238457oh48 or something. I didn't write it down.

I assume this giant passcode is key-generated from the system password. But, if that's the case, I see several problems. First of all, the encryption can only be as strong as your system password, and could be cracked by brute-forcing it. Second,  then can I never change my password again, or what? What if my password is compromised and I have to change it? I can't just instantly switch the encryption to use a different passcode, right?

[Perd Hapley]

I also got tired of those kinds of problems with Ubuntu.  Try Windows. http://store.microsoft.com/microsoft/Windows/category/1

[tyme]

After I logged in, the system helpfully told me that I could view my encryption passcode now, or do it later by running $somelongcommand and entering my password. I ran $somelongcommand, entered my password and got this giant thing like this: 8872f92xas2238457oh48 or something. I didn't write it down.

I assume this giant passcode is key-generated from the system password. But, if that's the case, I see several problems. First of all, the encryption can only be as strong as your system password, and could be cracked by brute-forcing it. Second,  then can I never change my password again, or what? What if my password is compromised and I have to change it? I can't just instantly switch the encryption to use a different passcode, right?

Ubuntu uses eCryptfs.

It works by randomly generating a key, encrypting your home directory with the key, and then encrypting that key with your user password (I use "password" loosely... there's no reason it shouldn't be a passphrase on any modern system that can handle >>8 character passwords).  Thus, it can re-encrypt the key if you ever change your user password.

edit... while the above is roughly correct, apparently eCryptfs is a bit more complicated than that... the randomly generated bit isn't a key used directly for encryption/decryption, but instead is a passphrase that gets hashed to generate two keys that are used internally by eCryptfs for different purposes: one to encrypt/decrypt file metadata, the other to encrypt/decrypt file-specific encryption keys.

I also got tired of those kinds of problems with Ubuntu.  Try Windows.

[Nitrogen]

http://www.linux-mag.com/cache/7568/1.html