[Cryptography] In search of random numbers
bear at sonic.net
Sat Oct 25 20:21:03 EDT 2014
On Sat, 2014-10-25 at 17:18 -0400, Theodore Ts'o wrote:
> On Sat, Oct 25, 2014 at 12:40:20AM +0200, Hanno Böck wrote:
> > > >
> > > > Most SSH keys are generated on first-time boot.
> > >
> > > This is dumb.
> > >
> > > This is bad design.
> > Do you have a smart alternative? What should these devices do? Pre-load
> > them with a key? (I don't particularly like that idea) Tell users they
> > need to generate a key on their Desktop for their new Internet of Things
> > light switch?
> You wait until the first time someone tries to connect to the ssh
> port, and generate the ssh key in a just-in-time fashion.
> > Basically most exploit-mitigation techniques (aslr, stack canaries)
> > these days require some kind of randomness.
> So the thing about aslr and stack canaries is that if they aren't
> perfectly random for the first boot, it isn't as catastrophic,
Also, if you don't connect to the network before you're finished
booting up, you can't be attacked over the network until you're
finished booting up.
And if you're not under attack yet, such things as stack canaries
have a bit less urgency....
There is such a thing as booting an operating system before the
network is connected!
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