Re: Encryption key changing the encryption logic.

From: Mok-Kong Shen (mok-kong.shen_at_t-online.de)
Date: 02/23/04 

Date: Mon, 23 Feb 2004 19:47:48 +0100

Douglas A. Gwyn wrote:
> Mok-Kong Shen wrote:
>
>> That's true for the common people. However, it's plausible
>> (certain?) that agencies like NSA do have and use secret
>> algorithms of their own. (Anyway, algorithms like AES are
>> not officially destined for encrypting classified top-secret
>> documents.)
>
>
> That's all irrelevant. While naturally one tries to keep
> the algorithm secret from opponents if possible, that's
> just because it makes the opponent's job even harder than
> it would otherwise be. Crypto algorithms are still designed
> to be impervious to attack even assuming that the enemy does
> find them out.
> While AES itself is not approved for use in protecting at
> three levels of classification, it is approved (in a
> certain mode) for use at two levels of classification.
> There are other systems already available for the highest
> levels of protection, and no incentive to discard them in
> favor of AES.
>

'Designed to be impervious' in the mentioned case means that
the agency has done its best with their secret algorithms
but the designs certainly don't benefit from 'public' reviews.
(I am assuming that crypto expertise in the public does at
least worth something. You might well question that assumotion.)
The 'other systems' you mentioned above are secret with respect
to the public. Hence they are relevant in the context of my
previous sentence.

M. K. Shen

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