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The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:13:59
Mark Tillotson (markt@harlequin.co.uk)
Fri, 18 Sep 1998 17:57:31 +0100
| RC4 usually sets up the block with the bytes 0-255 and then scrambles
| those depending on the key. This change XOR's the key with the 0-255
| and then scrambles it.
|
| One potential problem I can see is that you're not guaranteed to have
| all of the bytes anymore; you will probably have duplicates of some
| bytes and none of others. For an extreme example, say your key *was*
| the bytes 0-255; then this procedure would set the entire block to zero,
| which isn't very secure ;)
Much stronger than this, the suggested key schedule, in destroying the
permutation property of RC4, appears to render it *completely* broken,
as is easily demonstrated by experiment (in RNG mode it no longer looks at
all random) Hardly surprizing for a cipher designed around an
evolving permutation.
__Mark
[ markt@harlequin.co.uk | http://www.harlequin.co.uk/ | +44(0)1954 785433 ]
The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:13:59