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Comment by frankjr | Hacker News Reader

> This means that they’re often very large – easily the size of a whole movie.

Couldn't they just use actual units? This says absolutely nothing.

The article does later state Lets Encrypt's own expected worst case is 8 GBs in one CRL file in the hopefully unlikely scenario that every unexpired certificate they manage was revoked.

Merkle Hash Trees are the well-known solution for this, whenever they decide to update the protocols (was software patent encumbered til 2017)

Merkle Hash Trees are not a solution for offline checks. You can very easily check membership in a tree if someone sends you a proof of membership. But to get a proof, you'd either have to generate it yourself (meaning you're storing the whole set anyway) or get it from a third party (ie an online lookup, which is what OCSP is). The forefront of CRL design is in set compression techniques like Ribbon filters https://arxiv.org/pdf/2103.02515.pdf

I never said MHT are a solution for offline checks. That is a completely different problem space.

In the space domain, satellite ground systems have used a combination of guards, one way transmission, and others, although I am in favor of system-specific certificate whitelisting via running OCSP with local VAs, backed up by smart clients, with CRLs on the filesystem and in network shares.

CRL processing can cause timeouts, which is why it is always less preferred than the much more lightweight OCSP by comparison.

Furthermore, CRLs are blacklists, and newer OCSP is not exclusively, and, OCSP permits more flexibility with the various trust models that exist for it.

It sounds close to what the article suggests Let's Encrypt is using internally to store/generate the CRL files, though the article doesn't get into a lot of technical details to tell exactly if that is the case.

No. That isn't the same.

CRLs and OCSP are about individual certificates.

The beauty of Merkle Hash Trees for validation is it permits Statements e.g.

CAx = CA2 and 156 ≤ X < 343 (5)

The statement cj indicates that the certificate with serial number X = 156 issued by CA2 has been revoked, while the certificates with serial numbers from X = 157 to X = 343 (both included) issued by CA2 have not been revoked.

From https://www.researchgate.net/publication/220066804_Certifica...

Wouldn't a CRL that lists all the revoked certificates tell you that exact same information?

CRL's format is to list all the serial numbers in a blacklist, which means a CRL for a large well-used PKI is going to be gigantic by comparison to an MHT.

A CRL is not equivalent to modern OCSP, because modern OCSP can operate as a whitelist or a blacklist. However, CRLs are generally more secure than some of the OCSP variants because strong OCSP is used less (Nonced+authenticated/registered), and CRLs are not subject to replay attack like vanilla OCSP can be.

All the revocation checking mechanism have their pitfalls. It is a so complex issue. CRL has a very important benefit, namely it can be prefetched and can be updated regularly which is important in the case a firewall solution for instance. Read the following article for more details.

https://dev.to/coroner/why-do-certificate-revocation-checkin...

One Olympic swimming football bus tree worth of data.

When I was reading the thread the other day about a trees worth of oxygen from the MOXIE experiment, I couldn't help thinking: why not just use a term everyone is familiar with, litres per minute air.

Enough oxygen to sustain an adult at rest for x minutes.

I'm beginning to suspect there's an in-joke with science / tech writers about strained analogies.

And I'm not in.

> I'm beginning to suspect there's an in-joke with science / tech writers about strained analogies.

Which has been going on for longer than I've been alive. The idea (I assume) is to take a large number that's hard to conceive and turn it into something everyone can relate to.

But inevitably, they choose things that few can actually relate to, or things that are so vague/variable to be meaningless. It just adds more confusion all around.

It has to be an intentional joke.

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