[tor-dev] proposal 240: Early signing key revocation for directory authorities.
nickm at torproject.org
Sat Jan 10 20:46:32 UTC 2015
Title: Early signing key revocation for directory authorities.
Author: Nick Mathewson
This proposal describes a simple way for directory authorities to
perform signing key revocation.
We add the following lines to the authority signing certificate
revoked-signing-key SP algname SP FINGERPRINT NL
This line may appear zero or more times.
It indicates that a particular not-yet-expired signing key should not
3. Client and cache operation
No client or cache should retain, use, or serve any certificate whose
signing key is described in a revoked-signing-key line in a
certificate with the same authority identity key. (If the signing
key fingerprint appears in a cert with a different identity key, it
has no effect: you aren't allowed to revoke other people's keys.)
No Tor instance should download a certificate whose signing
key,identity key combination is known to be revoked.
4. Authority operator interface.
The 'tor-gencert' command will take a number of older certificates to
revoke as optional command-line arguments. It will include their
keys in revoked-signing-key lines only if they are still valid, or
have been expired for no more than a month.
5. Circular revocation
My first attempt at writing a proposal here included a lengthy
section about how to handle cases where certificate A revokes the key
of certificate B, and certificate B revokes the key of certificate A.
Instead, I am inclined to say that this is a MUST NOT.
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