[559] in cryptography@c2.net mail archive
Re: RC4 rollback/rollforward question
daemon@ATHENA.MIT.EDU (Eric Young)
Wed Apr 16 20:55:39 1997
Date: Thu, 17 Apr 1997 10:51:19 +1000 (EST)
From: Eric Young <eay@cryptsoft.com>
Reply-To: Eric Young <eay@cryptsoft.com>
To: Jim Gillogly <jimg@mentat.com>
cc: cryptography@c2.net, rodney@sabletech.com
In-Reply-To: <199704161620.JAA15329@zendia.mentat.com>
On Wed, 16 Apr 1997, Jim Gillogly wrote:
> This is unlike a CBC-type application, where you need to recover everything
> between xxx and yyy to start work on yyy.
Well not quite true. Given blocks
a b - - - f g
we could decode g but not f. You only need the preceeding cipher text
block to decode. So for ciphers with a block size of 8 bytes, you loose
the first 8 bytes of yyy.
eric
