RE: Editorial: Use of MAY in draft-ietf-ipsec-ikev2-algorithms

[Russ Housley <housley@vigilsec.com>]

Lee:

>I thought also that RC4 was not a restartable(seekable?) stream cipher and
>thus cannot tolerate lost or out of order packets unless special steps were
>taken (re-gen the key schedule for each packet?).

All stream ciphers use a key to produce a key stream.  WEP needs a 
different key stream for each packet, as would IPsec ESP if one tried to 
use RC4 in this context.  WEP achieved this by constructing a per-packet 
key.  An IV was simply concatenated with the rest of the key.  This is how 
the first three bytes of the packet key are "published."

Russ