An analysis of CRL sizes from various CAs

Some initial observations:

• Google's CRLs from the same intermediate CA (same public key) have different URLs and different content when pulled from different hosts (google.com, youtube.com).

• DigiCert has sharded according to 'assurance' class, algorithm, year and acquisition's name.

• Sectigo also has sharded according to 'assurance' class [1].

• GlobalSign has sharded by the yearly quarter presumably.

• HTTP Cache-Control maxage (or s-maxage), 'Expires' and 'Next Update' within the CRL file are not in sync.

• Some CAs other than Let's Encrypt also do not publish CRL URLs in the leaf certificates.

[1] https://www.sectigo.com/knowledge-base/detail/Sectigo-Interm...

We collected some data on the viability of only CRLs as the future (phasing out OCSP) - motivated by Let's Encrypt's announcement today [1].

Data is on CRL availability, number of entries, expiry & refresh times, etc. from various x509 leaf server SSL certificates.

[1] https://news.ycombinator.com/item?id=41046956

What analysis was done or are we just talking about the data gathering?

We'll be working on that in the coming days. Thought the data at this point was a good start.