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Date:      Mon, 3 May 1999 02:05:30 -0400
From:      "Allen Smith" <easmith@beatrice.rutgers.edu>
To:        Robert Watson <robert@cyrus.watson.org>, 0x1c <nick@shibumi.feralmonkey.org>
Cc:        freebsd-security@FreeBSD.ORG
Subject:   Re: Blowfish/Twofish
Message-ID:  <9905030205.ZM6442@beatrice.rutgers.edu>
In-Reply-To: Robert Watson <robert@cyrus.watson.org> "Re: Blowfish/Twofish" (May  3,  1:58am)
References:  <Pine.BSF.3.96.990503020707.5183L-100000@fledge.watson.org>

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On May 3,  1:58am, Robert Watson (possibly) wrote:
> 
> I don't believe so, as long as they are not just crypto algorithms.  I.e.,
> I believe our DES hashing is not exportable, whereas our MD5 hashing is.
> In a sense, it's all a matter of perspective on how you use an algorithm.
> It's all just mathematics, right?  Sort of like you can't patent
> mathematical formulas, but you can patent algorithms. :)  So SHA-1 support
> for FreeBSD would be quite exportable, I'd imagine, and would probably
> make a worthwhile addition.  I don't see Blowfish as a great addition
> other than the interoperability concerns expressed previously.

> On Mon, 3 May 1999, 0x1c wrote:
> 
> > On a similar note, is there any restriction on one-way hashing algorithms?
> > I forget.
> > 
> > Nick

One can use any cryptographically secure one-way hash function as a
(secret key) encryption method. The procedure is as follows:

Sender and recipient have shared secret key K. They want to transmit
information I. Sender takes three-bit chunks (the most efficient size)
of information I, finds a random salt S of sufficient size for each
chunk, and does:

	hash(K S I-chunk)

then sends the result and the random salt to the recipient.

Recipient then looks for the 2-bit combination that hashed as above
along with the secret and the key gives the result.

	-Allen

-- 
Allen Smith				easmith@beatrice.rutgers.edu
	


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