Simple encryption proposal. Comments ?

[Lulu of the Lotus-Eaters]

"Thomas Weholt" <2002 at weholt.org> wrote previously:
|Hm .... are you saying I'm better off using rotor? My first attempts used
|rotor, but storing rotor-encrypted data in values of HTTP-cookies didn't
|work very good, since cookie-values must  be in the
|string.lowercase+string.uppercase+'0123456789'

Sure.  You need to encode any encrypted value into the acceptable
alphabet.  Base64 encoding is simple enough though (you could also use
hex, or UU, or others, but base64 is the norm).

I do think you'd be better off with rotor than a pseudo-OTP system.  One
time pads (even fake ones) need to be way too long.  Normal symmetric
encryption can use reasonably short keys, and key-disposal schedules
that allow more than one use.  But a simple system that is stronger than
rotor was suggested by Paul Foley (I've done the same thing
independently, but his example was more formally coded).  Use SHA in
feedback mode to produce a bitstream for XOR with your plaintext.  SHA
is standard in Python, so you won't need to obtain anything extra.

Yours, Lulu...

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