Subject: Re: Plausible deniability (a feature to think about)

From: <[email-masked]>
Date: Thu, 22 Sep 2005 08:50:34 -0700

On Thu, 22 Sep 2005 07:52:08 -0700 "Daniel A. Nagy" 
<[email-masked]> wrote:

>Simply? How exactly do you suggest to share a common key so that 
>the parties
>can be reassured that it's their shared secret?

>> many variations of this are possible;
>> 
>> new signing subkeys, set to expire within hours of the message 
>> time,
>
>Again, how do you share them?

the sender generates the new keypair, and sends it signed and 
encrypted, to the receiver

it is neither more nor less trustworthy than the primary keys of 
the sender and receiver,
which could also conceivably be given to other parties,

>> split key systems with shares set to one, and split to only the 
>> receiver and sender keys, etc.
>
>I haven't seen split key implementations either in OpenPGP 
>compliant tools,
>though I know they are mentioned in RFC2440.

pgp has had them implemented since 6.x

a new type of pgp signature to deal with this issue was proposed by 

Ian Brown and Adam Back,
http://www.cs.ucl.ac.uk/staff/I.Brown/nts.htm

where the session key is signed, not the plaintext

(don't know if people want to explore this now, or wait until after 
the rfc 2440 is finalized, and save it for a further update,

i would welcome this useful type of signature, 
as i imagine many users would )

vedaal
>-- 
>Daniel

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