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1997-08-14 - Re: Encrypting same data with many keys…

Header Data

From: nospam-seesignature@ceddec.com
To: Ray Arachelian <sunder@brainlink.com>
Message Hash: de457537bf48d0195befe0b46c36c5934d0f84029341134746cb7ff34c7a7343
Message ID: <97Aug14.165930edt.32260@brickwall.ceddec.com>
Reply To: <Pine.SUN.3.96.970813170421.7599R-100000@beast.brainlink.com>
UTC Datetime: 1997-08-14 21:12:19 UTC
Raw Date: Fri, 15 Aug 1997 05:12:19 +0800

Raw message

From: nospam-seesignature@ceddec.com
Date: Fri, 15 Aug 1997 05:12:19 +0800
To: Ray Arachelian <sunder@brainlink.com>
Subject: Re: Encrypting same data with many keys...
In-Reply-To: <Pine.SUN.3.96.970813170421.7599R-100000@beast.brainlink.com>
Message-ID: <97Aug14.165930edt.32260@brickwall.ceddec.com>
MIME-Version: 1.0
Content-Type: text/plain



On Wed, 13 Aug 1997, Ray Arachelian wrote:

> On Wed, 13 Aug 1997, Bill Stewart wrote:
> 
> > The actual data is encrypted with IDEA, but the identical IDEA key is 
> > encrypted with each recipient's RSA key.  To avoid this attack,
> > PGP uses random padding after the IDEA key (which makes the message
> > encrypted with RSA different for each recipient, avoiding the trap.
> > Since IDEA keys are 128 bits long, and RSA moduli are typically 384-2047,
> > there's plenty of room for random noise in the format.)
> 
> Would it not be more secure if it picked a different IDEA session key for
> each recipient?  Would be slower, but...

If there were random padding, I don't think it would increase the
security.  PGP uses one conventional key and multiple PK encryptions of
it, with different padding (I think).  Then you only have one message to
send out, i.e. pk1,pk2...pkn,convenc instead of pk1,cenc1 pk2,cenc2...

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