[Cryptography] cheap sources of entropy

[Alan Braggins]

On 31 January 2014 01:09, Theodore Ts'o <tytso at mit.edu> wrote:
> Sure, if you have a "truly unpredictable source", you're
> golden, but is it really unpredictable?  Maybe the NSA has leaned on
> the sound board manufacturer which John Denker's Turbid generator is
> relying on, such that even though you *think* you're getting Johnson
> Noise, you're really getting something that has been very cleverly
> gimmicked to pass all the statistical tests, but in fact can be
> predicted by the NSA.  Or maybe the sound card has just failed in some
> interesting way that the author(s) of Turbid hasn't anticipated.

Or maybe you're running on a virtual machine, and the sound card is
being simulated, or shared with every other virtual machine using the
same hardware.

cf. http://blog.cryptographyengineering.com/2012/10/attack-of-week-cross-vm-timing-attacks.html

-- 
alan.braggins at gmail.com
http://www.chiark.greenend.org.uk/~armb/