First off, anybody could make a cipher called 'RC7'. RC7 isn't
trademarked, and 'RC' as a prefix isn't either. It's the same reason why
we have an MP4 unrelated to MP3, and why Intel makes Pentiums instead of
586's.
I'm a little confused about what exactly constitutes 'causing customer
confusion' with regards to using the term RC4. If I publish something
clearly labelled 'Bram's crypto library' and list RC4 as one of the
ciphers supported, there's no implication of anything coming from RSA, it
comes from Bram. There's always the trademark dilution claim, although my
understanding is that only applies to 'famous' trademarks, which RC4
clearly isn't, and the proper legalese response to a claim of dilution can
be roughly translated into plain english as 'blow me'.
-Bram
