Brad Huntting writes:
If I remember coorectly it's KerberosV uses an MD5 hash of /dev/mem.
Still, probably not 128 bits worth of entropy.
Mike responds:
Gee, that seems pretty amazing. On a typical workstation, there's a heck of a lot going on; in the megabytes of data in /dev/mem I'd think it quite unlikely that there's a practical way to predict or recreate a configuration.
Well, Assuming I was just creating a key and not doing something else at the same time, it would be pretty easy to predict what processes were running. It has about 6000 pages of physical memory.
From knowing what processes are running, you could probably narrow down the pages they would have in memory to at most half again that number. This gives you mabey 9000 choose 6000 posiblilitys for what process memory looks like. That gives about exp(3000*ln(7000)) or 2^37k posiblilities... I suppose that is more than 128 bits.
So if you cant predict which pages will land where in memory (which may be a false assumption), this is probably a good method for getting a random number on a unix box. brad