From: Adam Back <aba@dcs.ex.ac.uk>
Date: Thu, 16 Oct 1997 07:06:04 +0800
To: nobody@REPLAY.COM
Subject: Re: Equal rights for receivers
In-Reply-To: <199710150815.KAA25357@basement.replay.com>
Message-ID: <199710152254.XAA01167@server.test.net>
MIME-Version: 1.0
Content-Type: text/plain




Anonymous writes:
> Remind me again:
> 
> Why was it OK when the SENDER could choose to encrypt to an additional
> key, but it's a threat to the free world if the RECEIVER is allowed to
> request the same thing?

It's a threat to the free world if the RECEIVER is allowed to request
the same thing when PGP Inc also goes ahead and implements an enforcer
to bounce mail failing to meet this `request'.  This is not a
`request', this is an `insistance'.  This is a ready to roll system
which could be used as-is to implement GAK.

It is also potentially dangerous even without the SMTP policy enforcer
because if this functionality (CMR public key extension) is part of
the OpenPGP standard, then conformant OpenPGP implementations are pre
GAK enabled -- when GAK comes in, they know how to send to CMR keys,
and the enforcement can be added later.


Notice also that using comparisons with pgp2.x multiple recipient
functionality to deflect criticism is a complete red herring: pgp2.x
multiple recipients do not request copies mail to keys to be sent to
other keys.

All crypto recipients correspond 1-1 to message recipients, and in
most cases there is only one message recipient (and therefore only 1
crypto recipient).  This is better security, and it can't be used for
GAK anywhere near as easily as CMR.

And yes turning encrypt-to-self on violates 1-1 correspondence with
message recipients, but encrypt-to-self is also a security flaw to use
this feature.  I rant about the security risk of encrypt-to-self
periodically, as a search of the archives would show. 

Adam
-- 
Now officially an EAR violation...
Have *you* exported RSA today? --> http://www.dcs.ex.ac.uk/~aba/rsa/

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)]}\EsMsKsN0[lN*1lK[d2%Sa2/d0<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<J]dsJxp"|dc`