Messages in this thread | | | Subject | Re: Emergency shutdown feature | Date | Sat, 20 Dec 1997 21:04:37 +0100 | From | Olaf Titz <> |
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> and the above is user-space. Why not use a ssh 'like' > approach ? The packet -must- have come from a known host(s) > and -must- come from a trusted 'user' . the ssh package > already has this functionality, it would be nice to see > this used and not rebuild the wheel . Tia
The authentication used by the ssh package is much too heavyweight (public key calculations require a lot of CPU as well as rather much code for the multi-precision math) and not needed here. A simple keyed MD5 authentication is enough. I.e. take a string X as key and a non-constant string Z as message, and put (Z, MD5(X+Z)) in the datagram. Simple, fast, requires exactly one datagram and doesn't fall under US export restrictions (no encryption is done). Use a timer for Z to protect against replay.
There's not much of a wheel to re-invent here. (And we don't need tractor wheels for a bicycle. :-)
olaf
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