On 07/28/2010 10:05 AM, Perry E. Metzger wrote:
I will point out that many security systems, like Kerberos, DNSSEC and
SSH, appear to get along with no conventional notion of revocation at all.
long ago and far away ... one of the tasks we had was to periodically go by project athena to "audit" various activities ... including Kerberos. The original PK-INIT for kerberos was effectively certificateless public key ... aka replace registering a shared-secret password (for authentication) with a public key. There was then some amount of lobbying by the certification authority interests for pk-init to include certificate-based mode of operation (I wrote the draft-words for PK-INIT for inclusion of certificateless ecdsa).
An issue with Kerberos (as well as RADIUS ... another major authentication
mechanism) ... is that account-based operation is integral to its operation ...
unless one is willing to go to a strictly certificate-only mode ... where all
information about an individuals authority and access privileges are also
carried in the certificate (and eliminate the account records totally).
As long as the account record has to be accessed as part of the process ... the
certificate remains purely redundant and superfluous (in fact, some number of
operations running large Kerberos based infrastructure have come to realize
that they have large redundant administrative activity maintaining both the
account-based information as well as the duplicate PKI certificate-based
information).
The account-based operations have sense of revocation by updating the
account-based records. This can be done in real-time and at much finer levels
of granularity than the primitive, brute-force (PKI) revocation (and
replacement). For instance, have you gone over your outstanding balance or
credit-limit? ... are you up-to-date with you ISP account? ... or should it
just be temporarily suspended bending receipt of funds. Account records can
carry other kinds of real-time information ... like whether currently logged on
... and should duplicate, simultaneous logons be prevented (difficult to
achieve with redundant and superfluous, stale, static certificates).
The higher-value operations tend to be able to justify the real-time, higher
quality, and finer grain information provided by an account-based
infrastructure ... and as internet and technology has reduced the costs and
pervasiveness of such operations ... it further pushes PKI, certificate-based
mode of operation further and further into no-value market niches.
--
virtualization experience starting Jan1968, online at home since Mar1970
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