[503] in Kerberos
encryption question
daemon@TELECOM.MIT.EDU (Ted Anderson)
Mon Sep 12 15:48:32 1988
From: Ted Anderson <ota+@andrew.cmu.edu>
To: kerberos@ATHENA.MIT.EDU
Cc: Mike Kazar <kazar+@ANDREW.CMU.EDU>
I noticed a comment in Birrell's Secure RPC paper that suggested that
exchanging cipher text blocks resulted in no error propagation. It wasn't
clear that they were using pcbc so I tried a test case. The result is that
using pcbc, switching two cipher text blocks fails to affect any subsequent
blocks of plaintext. Has a fix for this problem been decided upon? How about
xoring the block count in with the plaintext & cipher text?
Ted Anderson
I checked up on this a bit and it seems that they were using only an XOR
checksum. Perhaps a CRC checksum would have worked better for Birrell's
problem.
ota
