Kent wrote: > > I think I figured out that the problem is /dev/random is "close to > > empty" when the computer's just booted, so I changed the line in > > /etc/crypttab to use /dev/urandom instead. That fixed it, so now it > > keeps going through the boot-up stuff right away. > > > > The problem isn't that the computer doesn't have much entropy when it > first boots (it stores the "pool" at last shutdown), the problem is that > it is being drained as you initialize your swap. OK. > > How insecure is it? > > Using /dev/urandom? Quite secure. > > Entropy estimation is a very tricky problem, and exactly when > /dev/random halts is kind of arbitrary. > > When your computer first boots it probably has a full entropy pool. That > is equivalent 4096 coin tosses: very hard to guess. The clues to those > 4096-bits of entropy left in your swap are not > easy to analyze. Want to be extra secure? Hit return a few times during > boot even if you do use /dev/urandom. > > How motivated is your foe? Unless someone very well funded--and very > motivated--is after your secrets, you are safe. And even if the > NSA/FBI/CIA *really* are interested in your bits, they still might not > be any better off if you use /dev/urandom instead of /dev/random. > /dev/urandom produces very high quality random bits. Thanks! Maybe this should be mentioned in the encrypted swap documentation? --------------------------------------------------------------------- dm-crypt mailing list - http://www.saout.de/misc/dm-crypt/ To unsubscribe, e-mail: dm-crypt-unsubscribe@xxxxxxxx For additional commands, e-mail: dm-crypt-help@xxxxxxxx
