I would like to know how high the level of entropy is when installing Ubuntu and encrypting the installation. As far as I know, the only partition that is not encrypted is the /boot partition because it has the boot loader unencrypted. When I use TrueCrypt to encrypt Windows, I am asked to move the mouse cursor inside the window to create a pool to improve the level of entropy.

As Ubuntu does not offer something like that, how can I be sure the keys, salts etc. are secure enough?

  • Interesting question, +1!. If you don't get an answer after a few days you could try reasking on security.SE. Please make sure to follow these guidelines on cross-posting, though. – Glutanimate Jul 29 '14 at 17:13

While you might not be asked to move your mouse, it will still help build entropy/feed your random number generator.

In Linux, /dev/random is your PRNG. /dev/urandom is fed by /dev/random, but provides more raw data to use.

Accessing data on HDDs, moving the mouse and typing are all actions that will help feed your random number generator.

Unfortunately, when you're in Ubuntu's LiveCD mode, you most likely will not have many things to do that might cause increases in entropy generation.

You can, however, rest easy and know that random number generation in Linux has been under peer review and should be safe. If you can't accept this for yourself, you're more than welcome to check out the kernel source.

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