[secdir] SecDir review of draft-ietf-calsify-2446bis-09

[Yaron Sheffer <[e-mail]>]

I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG.  These comments were written primarily for the benefit of the security area directors.  Document editors and WG chairs should treat these comments just like any other last call comments.

This document is a refresh of the 1998 iTip, an abstract transport protocol for iCalendar objects. This protocol is then instantiated for specific transports, e.g. RFC 2447, iMip (mail transport).

General

The original RFC 2446 security considerations seem extensive enough, and the proposed mitigations are reasonable. I believe the changes in -bis do not require additional work in this area (but see below).

Reality Check

If basing the entire security of the protocol on S/MIME may have been reasonable in 1998, today this is almost meaningless. S/MIME is too rarely used to protect mail in transit, and I would imagine its use to protect calendaring is even less prevalent.

Security

- In Sec. 6.2, replace "encrypted" by "encrypted and authenticated".
- An attack that is never mentioned is unauthorized creation of events. In many enterprise situations not everyone is authorized to invite the CEO, for example. Similarly, there may be tight control over who is allowed to delegate to whom. This obviously calls for an access control mechanism, something that is never mentioned in the document.

Nits

- 1.4: in table, objecy -> object
- 3.2.5 and 3.4.5: is MUST -> MUST



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