rotor alternative?

[Paul Rubin]

jjl at pobox.com (John J. Lee) writes:
> > > Second, if you have to have the key around anyway (true for some
> > > applications), it really doesn't matter how secure the algorithm is.

> Arguably XOR comes appreciably lower down the PITA
> scale, since the decryption algorithm is trivial: it may, for example,
> be implemented with an editor macro.

You're talking about using rotor in a protocol where the key is included
with the ciphertext.  In that case, you can decrypt without even bothering
to write an editor macro--you can just use the existing rotor module.

> In fact though, I'm really *not interested* in whether this argument
> is correct -- the mere fact that it's a valid way of thinking
> suggested to me that it was odd to deprecate the module, after
> (presumably) having put it in for this very purpose (obfuscation) in
> the first place.

To my mind deprecating it is a way of recognizing that it was a
mistake to include it in the first place.  Maybe in some farfetched
situation (Hollywood special effect movie) it makes sense to put an
explosive self-destruct charge into a car.  That doesn't make it
anything other than insane to include a self-destruct charge in every
car that rolls off an assembly line, triggered by a button on the
dashboard that you might press while trying to adjust the CD player.

Rotor should never have been shipped with Python.  If some application
programmer actually has a sensible use for it (I doubt this), then the
programmer should download the module from somewhere and ship it with
that specific app.

> However, if you're right in suspecting that anti-crypto legistlation
> is always (or even usually) applied without exception or waiver even
> to broken algorithms, then I agree it's pointless -- after all, AES
> would serve just the same purpose!

I'm going to have to catch up with the python-dev traffic about the
legislation issue but I think it's silly to leave crypto out of the
library because some regime somewhere doesn't permit its use.  Apache
2.0 now ships with SSL by default, and I don't think its popularity or
useability has been impaired.