Renewing expiring key - done correctly?

[Hauke Laging]

Am Di 03.12.2013, 19:26:09 schrieb Robert J. Hansen:

> Could you please share a realistic scenario by which an attacker could
> compromise a subkey without also having the ability to compromise the
> primary signing key?

That's really easy: In order to get access to the subkey which will sign this 
email you just need online access to the system on which I write this email. A 
system which is used to read a lot of email, for IM and for accessing the WWW.

It may (should) be harder to crack this system than it would be with the 
average system but it is without doubt possible (in the usual sense).

Compromising the respective mainkey is more difficult by several orders of 
magnitude. You would have to compromise at least the boot medium (CD/DVD) or 
the hardware I use.


> 	* There exist risk models in which an 'insecure system,' as
> 	  you would call it, is a perfectly reasonable place to
> 	  store a secret primary signing key

Of course. But these risk models are incompatible with the requirements of 
crypto usage in a business environment. They are even incompatible with a real 
Web of Trust.


Hauke
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