Danny

I could see that if the *only* channel he has for data is encrypted
then it would make sense to also send the timing encrypted.
However it is not clear that this is the only channel available
since there usually needs to be one in the clear to run the
key exchange.

There is an inconsistency between the introduction which
says that the service needs to be MITM resilient and section
3.2 which says that packet markers are a problem because
of MITM.

However I agree that timing packets have resilience that data
packets do not have and maybe it would be useful if someone
wrote a draft explaining this or pointing to material explaining
this so that the parameters and usefulness of any protection
scheme could be evaluated.

Stewart


On 07/03/2012 12:56, Danny Mayer wrote:
I have already said this before and I will repeat this for the purposes
of feedback.

Time packets do not need to be encrypted as not only do they not contain
anything secret, even if you knew the contents they are useless anytime
after the packet has been delivered.

You do yourself a disfavor in encrypting something that is not worth
encrypting. It takes processing overhead, increases packet size, and
there is no gain in doing so. You need to justify encrypting something
and please don't say that it is because some other document says to
encrypt everything. I want to know what is the benefit from doing so,
what are the risks in not doing so and what is the cost of doing so,
particularly in loss of accuracy, increased error budget, etc.

The whole thing is a bad idea from what I can tell.

Danny

On 3/6/2012 10:35 PM, Cui Yang wrote:
Hi, all,



I have posted a new draft that discusses the practical solutions for
encrypted synchronization protocols.



Since we have discussed a lot on this problem, and the security
requirement of synchronization also noted that confidentiality may need
protection, especially in case that the confidentiality protection is
mandatory. Synchronization should be available when the traffic is
encrypted. The influences by the encryption are explained, and several
possible solutions have been discussed.

The URL is below, please review and comment.



     Title      : Practical solutions for encrypted synchronization protocol

Author(s)  : Y. Cui,

M. Bhatia,

D. Zhang

Filename   : draft-cui-tictoc-encrypted-synchronization-00.txt

Pages     : 10

Date      : Mar. 1, 2012

    This informational document analyzes the accuracy issues with time

    synchronization protocols when time synchronization packets are

    encrypted during transmission. In addition, several candidate

   solutions on such issues are introduced.



A URL for this Internet-Draft is:

http://datatracker.ietf.org/doc/draft-cui-tictoc-encrypted-synchronization



Thanks,

Yang

==================

Yang Cui,  Ph.D.

Huawei Technologies

[email protected]
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