Re: [pkix] Validating Certs w/out reliable source of Time
"Dr. Pala" <director@openca.org> Mon, 08 October 2018 14:12 UTC
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To: "Panos Kampanakis (pkampana)" <pkampana@cisco.com>, PKIX <pkix@ietf.org>
References: <f1d0a721-96e4-5d1b-4dd3-7b041e3c4379@openca.org> <47b70e1c4d214e9297e29b9ee1450c59@XCH-ALN-010.cisco.com>
From: "Dr. Pala" <director@openca.org>
Organization: OpenCA Labs
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Date: Mon, 08 Oct 2018 08:12:39 -0600
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Subject: Re: [pkix] Validating Certs w/out reliable source of Time
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Hi Panos, all, thanks for the info. It seems nobody has a good story around it - the onboarding provides some obvious paths, but it does not provide really a good story around it and it is very prone to implementation errors (it seems more like giving up in having a good answer / system when you do not trust the network itself - which is the case I am trying to cover). Although I totally agree with the difficulty around providing a solution, I am a bit worried about devices keeping logs/audit traces and then follow up on them at a later time - especially without providing guidance about what is a trusted source of time... :D I would expect many devices not to really check the validity of certificates after they have been "used" already. In my specific use-case (which is not a generic case), I am leaning toward building a signed time service w/ a simple challenge-response mechanism that can be proxy and verified by the device... since we already have domain-specific trust anchors deployed, we might leverage those also for this use-case. Last but not least, it might be useful to define a TLS extension that would carry such a record so that time-synchronization becomes less of an issue... does such an extension already exists? Thanks again, Cheers, Max On 10/4/18 10:36 AM, Panos Kampanakis (pkampana) wrote: > > Hi Max, > > This is an issue that is dealt with in onboarding too. > https://tools.ietf.org/html/draft-ietf-anima-bootstrapping-keyinfra-16#section-2.6 > has some text around it. It states “It is reasonable that the > > notBefore date be after the pledge's current working reasonable > > date. It is however, suspicious for the notAfter date to be > > before the pledge's current reasonable date. No action is > > recommended, other than an internal audit entry for this.” > > IMO, if someone trusted a server cert chain because he didn’t have > proper time at the time, he should generate an audit log that can be > used to go back to validate when more accurate time available. > > There was also a discussion in LAMPS about trusting expired certs in > the initial enrollment > https://mailarchive.ietf.org/arch/browse/spasm/?q=%22Permissibility+of+expired+cert+renewal%22 > . Caching revocation info for the chain is important in these cases. > > Rgs, > > Panos > > *From:*pkix <pkix-bounces@ietf.org> *On Behalf Of *Dr. Pala > *Sent:* Thursday, October 04, 2018 10:22 AM > *To:* PKIX <pkix@ietf.org> > *Subject:* [pkix] Validating Certs w/out reliable source of Time > > Hi all, > > I am struggling with one issue that we have been seeing more and more > often with the introduction of small IoT devices that connect to > clouds and need to validate the other party's certificate chain. > > In particular, the problem is that without a reliable (or trusted) > source of Time information, devices can not really validate > certificates (i.e., is the certificate even valid... ? is it expired ? > is the revocation info fresh enough ?) and my question for the list is > about best practices in the space. > > Do you know if there are indications / best practices from ITU or from > IETF (or other organizations) on how to deal with this issue ? > > Cheers, > Max > > -- > > Best Regards, > > Massimiliano Pala, Ph.D. > OpenCA Labs Director > > OpenCA Logo > -- Best Regards, Massimiliano Pala, Ph.D. OpenCA Labs Director OpenCA Logo
- [pkix] Validating Certs w/out reliable source of … Dr. Pala
- Re: [pkix] Validating Certs w/out reliable source… Panos Kampanakis (pkampana)
- Re: [pkix] Validating Certs w/out reliable source… Rob Stradling
- Re: [pkix] Validating Certs w/out reliable source… Dr. Pala
- Re: [pkix] Validating Certs w/out reliable source… Tom Ritter
- Re: [pkix] Validating Certs w/out reliable source… Denis
- Re: [pkix] Validating Certs w/out reliable source… Dr. Pala