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Comment by veeti | Hacker News Reader

> The surprising aspect is that Authz has a validity of 300 days (which is likely to be increased)

This is not true. Authorization lifetimes are only going to get shorter and shorter [1], and have already been reduced to 90 days.

[1] https://community.letsencrypt.org/t/upcoming-api-changes/179...

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I've updated the blog post. I don't think, though, it has any material impact on the rest of the text.

Why not? Right now, compromised account keys give you the ability to issue certificates that are valid about as long as certificates are valid (or, in the worst case, +90 days from the original expiration date). Just about any scenario where the account key is compromised is one where the certificate's private key is compromised as well (not to mention typically one where you can just solve another challenge), so you're not really in a much worse position. Even less of a concern once authorizations are valid for only ~7 days.

> I've updated the blog post

You still state in your updated post that: "The surprising aspect is that Authz has a validity of 300 days (which is likely to be increased)" [emphasis mine]. This would appear to be incorrect based on the source cited above , where it is stated at "Eventually, we'd like to make authorization objects much shorter than certificate lifetimes, probably 7 days."

Perhaps it's worth updating the post again in light of this?

It is an interesting one - here is the original source (and there were many more mentioning 300 days).

https://community.letsencrypt.org/t/dns-authorization-lifeti...

It is from 14 June 2016 (a few months back), @pfg states "The CA/B Forum is currently developing new rules for domain validation and is probably going to settle on a validation period that is significantly longer than the 300 days currently in use ..."

Is there an authority to say which way it will go?

I think it's 36 months right now, but that's a Baseline Requirements thing, Let's Encrypt can (and does) use shorter periods. 36 months is the upper limit for all CAs. Let's Encrypt currently uses 90 days, and will go to something like 7 days in the near-future[1].

[1]: https://community.letsencrypt.org/t/upcoming-api-changes/179...

If you don't mind, I'd like to add to your blog post.

Token issues are something we solved about a decade ago. As to why LetsEncrypt has yet to learn these lessons, I leave that as an exercise to the readers and those familiar with security issues to discover for themselves.

Can I attribute this to a particular name?

The authorization lifetime should only last a few hours if that at best.

Let's Encrypt is slowly learning the lessons one should have learned a decade ago regarding tokens.

That does not give me hope for their future.

This is not a traditional token use-case (as you would use for e.g. a password reset email). We're talking about long-term identity keys (the account key) which are associated with authorizations for FQDNs, giving the owner of that key the ability to issue certificates for those FQDNs. The risk is not related to any kind of token, but rather to losing the long-term identity key, which really is no different from losing credentials for a more traditional CA (who can re-use these authorizations for up to 36 months).

The risk is that you're not using instantly-terminating tokens.

I've had over 20 years (way longer if you count BBS systems which had the exact same problems then as we have now) to play with this. I retired on this very concept.

How do authenticate yourself to get a new instantly-terminating token?

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