On Wednesday 21 September 2005 23:26, Hal Finney wrote:
This is a good point, I'll have to think about it. I'm still not
sure that covering this material with key fingerprints and keyids is
the right thing to do. What would the security threats be from being
able to bring a key back to life with the same fingerprint and keyid,
but without any signatures on it being valid?
It becomes a threat once you get hold of the private key (through some
accident, a data leak, whatever) because then you can also issue new
self-signatures.
I see two possibilities to limit the damage:
a) changing the expiration also changes the fingerprint, so the key does no
longer match whatever users have in their keyring and would basically be a
new key.
b) changing the expiration breaks ALL signatures (not only self-sig) on the
key. (Actually b must be implemented as well, when a is implemented.)
On the other hand: expiration dates are a very weak measure against key
abuse (they only limit the damage), un-revocable revocation sigs seem much
more effective to me.
Konrad
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