thoughts on RC4

[perry@imsi.com (Perry E. Metzger)]

I've been looking at the RC4 (or alleged RC4) code a bit.

Unlike most ciphers, RC4 doesn't seem to have any particular word
length dependancies in its principles. That is to say, a cipher like
IDEA has lots of magic numbers involved, but RC4 does not, which means
that one could, in principle, extend it from being byte oriented
stream to being word oriented stream without causing particular
harm. (It would, of course, become incompatible, but thats not a real
issue.) Can anyone see any reason why one could not change RC4 to
being a word oriented stream cipher, call it "ERC4"?

The reason I ask is because this would speed things up by a factor of
four on 32 bit machines, which would mean modest hardware could
possibly break 100mbps speeds. The 64 bit extension on 64 bit RISC
processors could go far, far, faster still.

This is a real consideration in the protection of network traffic,
where extremely fast encryption in software has been a stumbling block.

Perry