RE: Fwd: [DES-ANNOUNCE] New clients and 'spamming'

James Johnson (plexus@seanet.com)
Mon, 05 May 1997 12:31:17 -0700


Unfortunately to calculate the CRC of the DES block it would need to be
computed twice. This not only would cut our throughput by half, but much
more. All the optimization done would have to be refitted with CRC code. My
guess we would lose ~60-70%.

We could use a key based encryption (kind of ironic). The server could have
one key, and each machine randomly pick a key for that block. So upon a
block request the host would send it's 'public' key along with the request,
the sever would encode the reply, and tack its public 'key' to the end of
the message. Once the host recieved that information the it could decode
the message, crunch the DES block, and encode the reply with the sever's
public key.

The draw backs:
* Server must hold more information per host
* Server computation higher

Benefits:
* Easily verify authentisity
* Little impact on keys/sec

At 08:13 PM 5/5/97 +0100, you wrote:
>If the client send, in its answer, a kind of CRC (where you need to
>compute the whole block to get the same CRC), the server can, randomly,
>check that a given client gives the correct answer.

---
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