[Ntp] Re: Grease in Roughtime

[Marcus Dansarie <[e-mail]>]

Hi Kristof,

the point of greasing the signatures by providing bad time and bad 
signatures is to force implementations to check signatures, thereby 
preventing lazy implementations. Greasing signatures in this way has 
been in the text since Aanchal's first draft in 2019. The latest change 
just makes the purpose explicit.

Kind regards,
Marcus


On 2024-09-24 09:46, kristof.teichel=[e-mail] wrote:
> Hi Marcus,
> 
> thanks for doing my pull request and integrating my changes. I should 
> have done it earlier, but didn't.
> 
> About the GREASE section... can you explain the thinking behind randomly 
> sending faulty packets?
> a)     How would anyone (other than the client itself) even know whether 
> or not the client reacted correctly (discarding a packet with 
> inconsistent data or an invalid signature)?
>      I don't think I see who would even evaluate this as a test, much 
> less how this could "ensure that clients validate signatures".
>      What am I missing here?
> b)    Wouldn't it make more sense to send packets with a valid timestamp 
> but invalid signature - so that in the case of misbehaviour (accepting 
> the time in spite of incorrect signature), nothing terrible would happen?
> 
> 
> Besten Gruß / Kind regards,
> Kristof Teichel
> 
> __________________________________________
> 
> Dr.-Ing. Kurt Kristof Teichel
> Physikalisch-Technische Bundesanstalt (PTB)
> Arbeitsgruppe 4.42 "Zeitübertragung"
> Bundesallee 100
> 38116 Braunschweig (Germany)
> Tel.:    [phone]
> E-Mail: [e-mail]
> __________________________________________
> 
> 
> 
> Von: "Marcus Dansarie" <[e-mail]>
> An: [e-mail]
> Datum: 23.09.2024 22:49
> Betreff: [Ntp] Re: Grease in Roughtime
> ------------------------------------------------------------------------
> 
> 
> 
> Thanks for the comments!
> 
> I just made a pull request on Github
> (https://github.com/ietf-wg-ntp/draft-roughtime/pull/4 <https:// 
> github.com/ietf-wg-ntp/draft-roughtime/pull/4>) that should
> clarify how grease is used in Roughtime. It also addresses most of
> Martin and Kristof's comments.
> 
> On 2024-09-17 13:52, David Venhoek wrote:
>> First of all, regarding the ver tag, there is no requirement for
>> servers to ignore unknown versions in that tag. this means that
>> technically it is valid behavior right now for a server receiving
>> unknown versions to reject that packet, even if there is version
>> overlap. This seems highly undesirable
> 
> I don't think I fully understand the problem you are describing here
> however. Could you give an example?
> 
> Kind regards,
> Marcus
> 
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