[pkix] Connected Cars. Upgradable/Replaceable IoT systems. Re: Managing Long-Lived CA certs

Anders Rundgren <anders.rundgren.net@gmail.com> Fri, 21 July 2017 05:01 UTC

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From: Anders Rundgren <anders.rundgren.net@gmail.com>
To: pkix@ietf.org
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Date: Fri, 21 Jul 2017 07:01:42 +0200
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Subject: [pkix] Connected Cars. Upgradable/Replaceable IoT systems. Re: Managing Long-Lived CA certs
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My guess is that 10-15Y+ old connected cars won't be permitted on public roads unless they are upgraded.
Upgrading really old cars will become a major task since the electronics is unlikely to actually be upgradable.


On 2017-07-21 05:23, Anders Rundgren wrote:
> Hi,
> It is not uncommon that there are more than one imaginable solution to a problem.
> In this case there is an obvious alternative to what is proposed.
> Assume that a system * in some way becomes obsolete.
> If such a system represents a considerable investment AND needs to live for decades, it should be upgradable.
> If OTOH the system is not upgradable, it should be replaced.
> If an IoT device only supports outdated algorithms it is anyway vulnerable to attacks making workarounds on the CA side fairly useless.
> BTW, who in their right mind would run a CA with compromised keys or a CA for obsolete devices?
> Anders
> * System in this context involves the entire infrastructure, including possible CAs.
>> Hi PKIX,
>> I have a small question for the list regarding long-lived CA
>> certificates. Especially in the context of device certificates, we often
>> see the use of extra long-lived certificates for Root and Sub CAs (e.g.,
>> 35+ years) combined with limited key sizes (e.g., p256).
>> Until we have a supported mechanism for reprovisioning devices (...),
>> one possible solution for limiting the exposure of the private key would
>> be to have a scoped certificate issuance period.
>> What I am thinking about would be adding an extension that says: "This
>> CA can issue certificates from up to 5 years from the validFrom, after
>> this, just use it to provide revocation information". This might provide
>> some protection in case the CA key is compromised after the initial 5
>> years of validity (e.g., certificates issued after that date shall be
>> rejected).
>> Does such extension exists today ? If not, could this be some work for
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