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Re: Improving resistance against attacks
Nice thinking, Patrick, but why go to all that trouble when there is a key
generator that continually generates unpredictable keys of any size as often
as you want and synchronizes them across a link without transmitting any
info about them. It's called the ASK ToolKit(tm). See www.keygen.com
Regards,
Myron Lewis,
President,
KeyGen Corporation.
781-860-0108
-----Original Message-----
From: Robert Hettinga <rah@xxxxxxxxxxxxxx>
To: espam@xxxxxxxxxxxxxxx <espam@xxxxxxxxxxxxxxx>
Date: Wednesday, December 17, 1997 9:14 AM
Subject: Improving resistance against attacks
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>From: Patrick Feisthammel <pafei@xxxxxxxx>
>Reply-To: Patrick Feisthammel <pafei@xxxxxxxx>
>To: ietf-open-pgp@xxxxxxx
>cc: Patrick Feisthammel <pafei@xxxxxxxx>
>Subject: Improving resistance against attacks
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>-----BEGIN PGP SIGNED MESSAGE-----
>
> Hi!
>
> After the thread about weak RSA keys in sci.crypt, I tought about
> improving the security against attacks on the public keys.
>
> My propoal in short: Use multiple keys at the same time.
>
>
> Why using multiple keys at the same time
> ========================================
> If a key is generated, there is a probability p, that there is a 'fast'
> algorithm to factorize this key. For two keys, the probability, that
> both are 'easy' to break is p^2. And therefore much smaler.
>
>
> How it works
> ============
> To encrypt some data d with two keys K1 and K2:
> 1. Create a one time pad o (random data) of the same length as d.
> 2. Encrypt the data d with o: c1= E(d, o)
> 3. Encrypt the result from step 2 with the key K1: c2= E(c1, K1)
> 4. Encrypt the one time pad with key K2: c3= E(o, K2)
> 5. The encrypted data is the concatenation of c2 and c3.
>
> To decrypt:
> 1. Decrypt c3 with K2: o= D(c3, K2)
> 2. Decrypt c2 with K1: c1= D(c2, K1)
> 3. Decrypt the data: d= D(c1, o)
>
> If key K1 is broken, only c2 can be decrypted. Because without the one
> time pad o, the knowledge about the data is still zerol
> If key K2 is broken, the one time pad is known, but this also does not
> give any information about the data d.
>
> Some thougths have to be done for multiple recipients, that two broken
> keys of different recipients don't reveal the cleartext.
>
>
> Communication with PGP 2.6.x and PGP 5.x
> ========================================
> The usage of two keys can easaly be added to the today version with
> one key:
> - Add the information about the key id of the second key in the
> public key, as non critical information.
> - pgp-2keys checks if the receipient has a one-key public key. If he
> has, the old encryption/signing is used. If not, the new system is
> used.
> Users of pgp-1key will always encrypt/sign with only one key, which is the
> today used scheme. pgp-2key users can communicate with the schema
> proposed in this mail.
> This way it is fully compatible with todys versions. (Or at least as
> compatible as today versions)
>
>
> 2 keys or m keys
> ================
> Of course, this system can easaly be extended to the more general case
> of m keys. The keys could even be from other key algorithms.
>
>
> What do you think? Would this be a suitable way to reduce the risk
> given by the usage of one signle key?
> Could this be an idea for later versions of OpenPGP?
>
>
> Cheers, Patrick
>
>
>
>
>
>
> - --
> PGP-KeyID: DD934139 (pafei@xxxxxxxx) encrypt mail with PGP if possible
> more about PGP on http://www.rubin.ch/pgp/ (in german only at the moment)
>
>
>
>
>
>
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>
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