On Thursday, April 3, 2003, at 10:01 PM, J C Lawrence wrote:
Note that the Porkhash proposal doesn't use signatures or keys, just an
MD5 hash of items with a secret. Under the porkhash proposal anybody
wishing to verify a hash has to contact a system which possesses the
secret, for re-computation of the hash to see if it matches. This
requires the secret to:
a) be on an exposed system.
b) be on a system which can be systematically explored and tested in
attempt to deduce the hash.
Neither are optimal conditions.
There's nothing that says the secret needs to persist very long. You
are free to alter the secret for every combination of senderid and
timestamp if you like. Probably a secret keyed on the timestamp would
be sufficient; then it's not all that material that the system which
validates hashes can be systematically explored. Sharing 365 secrets
(one per day of the year) is not materially harder than sharing 1
secret.
C
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