Packing Kerberos Tickets into X.509 certificates

[Rick van Rein]

Hello,

Attached is an X.509 certificate holding a Kerberos Ticket as public key
info and an Authenticator with the checksum SHA1(TBSCertificate) as a
certificate self-signature.  A demo that generates such self-signed
certificates from within a MIT krb5 environment is on
https://github.com/arpa2/kerberos2pkix

This is somewhat wild, but it does not appear to conflict X.509, which
is very general and uses OIDs to indicate the form of public key info
and certificate signature.  The new thing is that it doesn't use public
key crypto but an infrastructure that makes similar things possible with
public Tickets encapsulating symmetric keys, so it will be limited to
session with a known X.509 recipient.  I am interested in responses,
including those that explain feelings of why this is "right" or "wrong".

I found this in trying to get Kerberos integrated into TLS as naturally
as possible.  This approach is the most natural option I found, roughly
requiring a new "Kerberos" signing algorithm for TLS, and adding TLS'
hash algorithms to the list of checksum types for Kerberos'
Authenticators.  If you see other potential applications for X.509
certificates with Kerberos contents, I'd be interested in hearing those too.

Cheers,
 -Rick

-----

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 0 (0x0)
    Signature Algorithm: 1.3.6.1.4.1.44469.666.509.88.1.1.2.1.3.14.3.2.26
        Issuer:
        Validity
            Not Before: Oct 16 12:42:11 2015 GMT
            Not After : Oct 16 12:47:11 2015 GMT
        Subject:
        Subject Public Key Info:
            Public Key Algorithm: 1.3.6.1.4.1.44469.666.509.88.1.1.1
            [OpenSSL was not updated to interpret this new OID - Rick]
             Unable to load Public Key
140277261715112:error:0609E09C:digital envelope
routines:PKEY_SET_TYPE:unsupported algorithm:p_lib.c:239:
140277261715112:error:0B07706F:x509 certificate
routines:X509_PUBKEY_get:unsupported algorithm:x_pubkey.c:155:
    Signature Algorithm: 1.3.6.1.4.1.44469.666.509.88.1.1.2.1.3.14.3.2.26
    [OpenSSL can dump the generic BITSRTING for this new OID blindly - Rick]
         30:81:8b:a0:03:02:01:12:a2:81:83:04:81:80:ae:ab:e4:69:
         87:51:25:ac:1b:6a:13:99:c1:23:60:08:b7:8a:de:7b:c3:b1:
         b7:4e:0d:b4:33:83:9c:b7:cf:66:0b:cc:ab:90:b6:96:1a:2e:
         81:7f:ac:c8:60:32:80:6c:ba:8b:57:dc:31:f8:5d:c6:bf:82:
         65:c0:9a:29:2e:9d:27:7d:eb:e5:9c:01:80:63:0f:6e:89:6d:
         47:d3:05:c6:05:56:d1:ad:1b:0e:89:12:e2:02:7a:ca:a5:1d:
         c4:4f:04:7f:39:1e:63:f3:ee:69:5b:ee:fd:8b:c4:45:0b:5c:
         3b:47:c8:96:78:39:b5:45:3d:45:de:c8:e9:de:26:6f

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----