[Ndn-interest] Ndn clock synchronization requirements

Viktor S. Wold Eide viktor.s.wold.eide at gmail.com
Fri Jun 14 03:22:24 PDT 2019

On Thu, Jun 13, 2019 at 7:58 PM Mosko, Marc <mmosko at parc.com>
<mmosko at parc.com> wrote:
> SignatureTime and SignatureSeqNum are both in the current NDN spec.  SignatureTime has been around since the beginning.  I am not sure when SignatureSeqNum was introduced.  SignatureTime may be used both in signed Data and signed Interest.
> The SignedInterest spec (http://named-data.net/doc/NDN-packet-spec/current/signed-interest.html) has an explicit dependency on CurrentTime() being loosely synced (a 60 second grace period) to determine if the first interest with a key is valid, then it slides forward from that time if SignatureTime is used.
> One could use a SignatureNone (and remember a nonce history) or SignatureSeqNum instead.
> I agree with your premise that one should be explicit about time dependency -- which components have it and why and how can one use a alternatives if desired.

OK, thanks.

I see that SignatureTime may be present or not, and that there are
other alternatives such as SignatureNonce/SignatureSeqNum.

The question then becomes - is SignatureTime used in any way in any of
the core protocols / software?

If any core protocol / software relies on SignatureTime, then clock
synchronization becomes a hard requirement.

It that is not the case, then nothing in the core protocols / software
should fail if clocks are not synchronized, not from SignatureTime at

I understand that it might not be such a clean cut, but I would appreciate
if someone could share their insight in this respect.

Best regards
Viktor S. Wold Eide.

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