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Re: OCSP and CSL



Brian Tvedt wrote:
> 
> If I was that concerned about misuse of my private key, I would password protect
> it.  This seems much superior to relying on a complicated mechanism (CSL) being
> correctly implemented in every security application out there.

My private key IS password-protected, and nonetheless I
could fear its misuse should I forget it around. This fear
is even greater in Public Administrations with automatic
signature servers. Since the law explicitly states that such
servers sign on behalf of a real person, this guy has a real
fear to be held responsible for signatures emitted during
non-working hours. And as these servers typically use a
crypto board, it is not that easy to disable it (could be
used for SSL support too).

Revoking and issuing new certs is a real trouble, especially
when a smart-card (Or crypto board) with one-time on-board
private-key generation is involved.

Perhaps I have the wrong understanding of the Hold code in a
RFC-2459 conformant CRL. I could not find a clear definition
of how is a certificate "temporarily suspended" and yet
placed in a CRL. In my understanding, a CRL is a
monotonically non-decreasing list of revoked certificates.
There is no way to state that a cert is valid again. Issuing
another cert for the same key is simply not possible in
certain environments.
Either a CRL is augmented in meaning to be a list of invalid
certs within specific timeframes (i.e. invalidity start -
invalidity end, the latter being infinite for truly revoked
certs), or a separate concept has to be created: CSL.

OCSP can then be the vehicle to convey punctual information
about a cert status, but given teh current legislation in
several countries, CRLs (and may be CSLs) have to be
produced and archived for legal use.

Antonio Lioy

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