Question on CFB variant with c[i-N]
David Honig
honig at otc.net
Mon Dec 22 10:17:32 PST 1997
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 at otc.net Intaanetto Jigyoubu
"Windows 95 is a technologically complex product that is best left alone by
the government..."
---MSFT Atty B. Smith
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