Re: High Quality Random sources, was: Re: SecuriKey

[Stephen D. Williams]

I was only commenting on the random source, not the rest of the 
discussion about what a particular keyfob does.  Most useful crypto is 
public-key, i.e. asymmetric encryption, but one-time-pad is a useful 
fallback since it really is unbreakable if you have a truly random source.

OTP absolutely requires that you share the OTP out of band, i.e. you 
twin a capture of random data.  Any transfer makes it as vulnerable as 
the transfer method.

sdw

tabris wrote:

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> On Sunday 11 January 2004 10:38 pm, tabris wrote:
>  
>
> > On Sunday 11 January 2004 7:39 pm, Stephen D. Williams wrote:
> >    
> >
> > > Impossible?  I think not.  Some "mechanical" devices do exhibit true
> > > random capability, especially when enhanced by algorithmic means.
> > > To wit:  http://www.lavarand.org/
> > >
> > > Let me know if you can prove their methods don't provide a true "high
> > > quality" random source.
> > >
> > > I'd like to see their code as a module with an automatic test to make
> > > sure that the random source is high quality.  In this case, that
> > > would mean making sure that the cap was not off the camera.
> > >      
Or, at least if it was that it was pointing at a Lava Lamp!

> > > sdw
> > >      
> > 	just because it passes tests of entropy and probability doesn't make
> > it random. it just gets really really close. [hence pseudo-random]
> > Everybody knows that /dev/random isn't truly random (it's still a state
> > machine, dependent on a hash algorithm [chosen b/c they can take a
> > non-random source and make it 'LOOK' random], and you feed it with data
> > that is not totally predictable. BUT, there are still enough ways to
> > exploit it if you can control/influence the input). it just can pass
> > enough tests so that it can be used.
> >    
> tere are devices such as this that I admit to not knowing of until now...
>  
>
> > 	and that still doesn't answer the question of how one would use [such
> > a device] to 'generate a one time pad'. a one time pad must be
> > possessed by both parties that are communicating. and if you have a
> > secure channel to transmit an OTP, then you have one that can carry a
> > message as well (most commonly, an OTP is used with a time delay. there
> > is a single time when a secure channel is available. one [or both] of
> > the parties brings it with him/her when he/she travels.
> >
> > 	so i'd believe that mebbe this Securikey could hold one... but, any
> > USB key-fob type device can.
> >    
> Perhaps I should make an amendment. you could perhaps put a geiger counter 
> and cobalt or other radioactive source into a key fob... but i don't 
> think it would ever be considered 'safe' to carry.
>
> other sources may be available as well (i admit to not getting the time to 
> read the website until just now). doesn't look like it fits in a USB 
> key-fob yet tho.
>  
>
> > 	I'm sure that someone else can be more knowledgeable on this than I,
> > but the general theory holds fast.
> >    
>
> - -- 
> If it's worth doing, it's worth doing for money.
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