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Comments on CRL issuance after certificate revocation in draft-ietf-ltans-notareqs-02
We were sent some comments on the -02 draft, I thought
I should forward the substantive comment for mailing
There was a comment on
The problem with CRLs is that they might not be synchronized with
revocation mechanisms and there is no real information whether a
signature is valid or not at specific point in time. In theory CRLs
should be issued immediately after a certificate is revoked.
The comment was:
This is not advisable, because this “on the spot” CRL issuance
paves the way to man in the middle / replay attacks.
An attacker could store a CRL issued before implementing a, say,
private key compromise attack. After the attack the attacker could
intercept CRL retrieval requests issued before the CRL nextUpdate
time and send back the requester the previous CRL, where the revoked
certificate is not listed. If the nextUpdate time has not yet expired
the relying parties would trust the CRL they receive, without having
a means to realise it is the old one. If instead CRLs are issued only
at nextUpdate time, or just slightly before, RPs would be aware they
should wait until the so called “grace period” expires. CAs could
take no responsibility on verifications based on CRLs issued before
the “grace period”. By grace period it is intended the time necessary
for a revocation request to be processed by the revocation management
service to make it available to relying parties. If such request is
submitted to the revocation service too close to the next CRL issuance
time to be included in it, then the revocation will be published in
the subsequent CRL. Please see CWA 14171 section 5.3 for details
(There were a couple of editorial comments, e.g., "When speed is not of essence"
should probably be "When speed is not of the essence"