1997-12-22 - Question on CFB variant with c[i-N]
Header Data
From: David Honig <honig@otc.net>
To: “Johnson, Michael P (Mike)” <cypherpunks@Algebra.COM>
Message Hash: 16e496cf8b99615bb6f9d451c81e1ed59b75174c0433c81e236881c5a2945d6a
Message ID: <3.0.5.32.19971222091025.007aee10@otc.net>
Reply To: <c=US%a=_%p=Stortek%l=LSV-MSG06-971221014643Z-85371@lsv-bridge.stortek.com>
UTC Datetime: 1997-12-22 18:17:32 UTC
Raw Date: Tue, 23 Dec 1997 02:17:32 +0800
Raw message
From: David Honig <honig@otc.net>
Date: Tue, 23 Dec 1997 02:17:32 +0800
To: "Johnson, Michael P (Mike)" <cypherpunks@Algebra.COM>
Subject: Question on CFB variant with c[i-N]
In-Reply-To: <c=US%a=_%p=Stortek%l=LSV-MSG06-971221014643Z-85371@lsv-bridge.stortek.com>
Message-ID: <3.0.5.32.19971222091025.007aee10@otc.net>
MIME-Version: 1.0
Content-Type: text/plain
At 06:46 PM 12/20/97 -0700, Johnson, Michael P (Mike) wrote:
>
>
>>> cfb Ciphertext feeback mode
>>> c[i] = f1(K, c[i-1]) ^ p[i]
>>> p[i] = f1(K, c[i-1]) ^ c[i]
>
Suppose instead of c[i-1] you use c[i-N] where N is say 10.
How would you prove that this has no security implications?
That 10-way interleaved cfb streams are security-equivalent to
a single cfb stream interleaved with the immediately previous block?
------------------------------------------------------------
David Honig Orbit Technology
honig@otc.net Intaanetto Jigyoubu
"Windows 95 is a technologically complex product that is best left alone by
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Thread
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Return to ““Johnson, Michael P (Mike)” <JohnsMP@LOUISVILLE.STORTEK.COM>”
- 1997-12-21 (Sun, 21 Dec 1997 09:51:32 +0800) - RE: ECB, CBC, CFB, OFB - “Johnson, Michael P (Mike)” <JohnsMP@LOUISVILLE.STORTEK.COM>
- 1997-12-21 (Sun, 21 Dec 1997 15:28:21 +0800) - RE: ECB, CBC, CFB, OFB - Bill Frantz <frantz@netcom.com>
- 1997-12-22 (Tue, 23 Dec 1997 02:17:32 +0800) - Question on CFB variant with c[i-N] - David Honig <honig@otc.net>
- 1997-12-24 (Wed, 24 Dec 1997 13:32:28 +0800) - Re: Question on CFB variant with c[i-N] - Bill Stewart <bill.stewart@pobox.com>
- 1997-12-22 (Tue, 23 Dec 1997 05:03:43 +0800) - Re: Question on CFB variant with c[i-N] - Bruce Schneier <schneier@counterpane.com>