Tom Yu wrote:
> Sam Hartman <[email protected]> writes:
> 
> > We use token types 06 01 and 06 02 for initial context tokens.
> >
> > However, RFC 4121 section 4.4 reserves token ID 06 01 through 06 ff in
> > order that you can unambiguously distinguish ASN.1 wrapped framing from
> > other framing.
> 
> RFC 4121 Section 4.4 reserves 60 00 through 60 FF.  The BER identifier
> octet for "Application tag 0 (constructed)" is 0x60, not 0x06.  (0x06
> would be "Universal tag 6 (primitive)", also known as "OBJECT
> IDENTIFIER".)

Correct.  0x60 will be the first byte of a "generic framing" as it
must be present on the initial context token as described in
rfc2743, Section 3.1  Mechanism-independent token format (bottom of page 81)

 http://tools.ietf.org/html/rfc2743#page-81

      1. 0x60 -- Tag for [APPLICATION 0] SEQUENCE; indicates that
      -- constructed form, definite length encoding follows.

The Kerberos rfc1964 gssapi mechanism decided to (re-)use that generic
framing on all context-level tokens, plus on all per-message tokens.

rfc4121 dropped the generic framing on the per-message token,
and the quoted rule (and exemption for token IDs (60 00 -- 60 ff)
is to enable a cheap heuristic to recognize whether a generic
framing is present on a Kerberos per-message token.


-Martin
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