Re: Key Escrow Good, GAK Bad

17 Dec 2003

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In <199701092357.PAA23840@slack.lne.com>, on 01/09/97 at 07:57 PM,
   Eric Murray <ericm@lne.com> said:
...
Ken Kirksey writes:
...
...
To me, Key Recovery cryptography is like using a condom with a
hole in it. No thanks.
I agree in principle, and I doubt I would ever use a key recovery system 
if I had a choice.  But, speaking as a network manager, I know that 
private key recovery (not GAK) can be an enhancement to security.
I'll give an example.  About a year ago, my boss wanted to protect his 
file of annual financial projections for the company from prying eyes on 
our Macintosh network.  I installed CurveEncrypt on his machine, showed 
him how to use it, and gave him the standard lecture on choosing a good 
passphrase.  I stressed that he needed to chose a passphrase easy to 
remember, because if he forgot it, there was no way to get his file back.
Well, he forgot his passphrase.  He spent an hour trying every 
combination he could think of, interjecting a curse here and there for 
color.  He is now totally off using encryption to protect sensitive 
information.
...
User education would be even easier than key escrow.  Your boss could
have shared that passphrase with one or more other people, ideally the
people who helped him make the report.  When you encrypt something
that's vital to the company, you need to make sure that it can be
gotten back.  In most companies, there's more than one person who
is 'cleared' for even the more vital information.  The keys to
those files should be shared amongst those people.
...
Unfortunately, few encryption programs make this easy.  And even though
you can do it in PGP by encrypting to multiple recipients, how many
people think to do so?  I don't.  Most programs assume that there's one
key that that's used to encrypt everything, hence one level of security-
the highest.  But in a business situation you really need to be able to
encrypt something with your key and your secretary's key, or the keys of
all the board members, etc.
Would not this be the perfect senario for the implementation of Shamir's Secret Sharing?
Rather that having several people being able to access the data
independent of each other having a shared key where it requited say 3 out of
5 members to access the data?

That way a breach of security of one key does not result in a breach of security of all
data.

Are there any know implementations of this?

Thanks,

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