On Sep 15, 3:06pm, Perry E. Metzger wrote:
Assuming for the moment that alleged-RC4 came from the keyboard of Ron Rivest,
Well, from his mind -- its probably a reverse engineering job. It looks like it may be interoperable, which would imply that its real...
If it is, then the person who did it has gone to a lot of trouble to make the source layout and coding style very similar to the publicly available MD[245] sources. Compare them and you'll see what I mean. One of the original reasons I thought that this was a fake was the similarity (adds credibility), but when it was verified I began to think that this is, in fact, the real source from RSADSI. I don't think that this is a reverse engineering job, because I can't see any motive for anyone to put the work into making the code look so similar.
Hard to tell. Its remarkably simple -- the simplest cypher I've seen in some time. It obvioously needs to be studied in detail. The possible excitement comes from its speed...
I think that we must bear in mind that most of us are familiar with block ciphers, and that there aren't a lot of stream ciphers out there which are widely used right now. The only others I know of are the various LFSR's (which are pretty simple themselves), and that alleged early prototype A5 (which was itself a group of LSFR's too). Ian.