[cryptography] airgaps in CAs

Steven Bellovin smb at cs.columbia.edu
Sun Jan 8 21:10:56 EST 2012


On Jan 8, 2012, at 6:29 26AM, Florian Weimer wrote:

> * Eugen Leitl:
> 
>> Is anyone aware of a CA that actually maintains its signing
>> secrets on secured, airgapped machines, with transfers batched and
>> done purely by sneakernet?
> 
> Does airgapping provide significant security benefits these days,
> compared to its costs?
> 
> File systems are generally less robust than network stacks.  USB
> auto-detection is somewhat difficult to control on COTS systems.  So
> unless you build your own transfer mechanism, a single TCP port
> exposes less code, and code which has received more scrutiny.

While I'm uncertain about your precise conclusion -- I know of no
attempts to write a USB+file system+OS behavior security sanitizer,
so I don't know how easy it is to do -- you're definitely asking
the the right question.  Security is not a matter of good or evil
technology; it's a matter of picking the best choice from a perspective
of maximizing benefits, minimizing costs and risks, and doing all
of that in a dynamic environment without complete knowledge of even
the current state, let alone the future.  


		--Steve Bellovin, https://www.cs.columbia.edu/~smb








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