Can a CRL file contain multiple full stops in its name?

Question

Will a CRL file name such as fred.freddy.domain.crl work for a Certificate Revocation List URL? I cannot find any documentation to state that it will not work.

Closest that I have found is a recommendation that it should not be done in the following article: Designing CRL Distribution Points and Authority Information Access locations. Specifically:

Now, we need to design a URL form. This means that we need to design the name for CRT/CRL file, virtual directory (if necessary), separate host (if necessary). There is no significant recommendations, except that file name should be simple and do not contain spaces and/or special characters.

Is anyone aware of a specific issue with using a dot notation for a CRL file? It works nicely with a current naming convention that we have and would easily allow admins be able to follow the pattern when creating new Issuing CA's in our environment.

Answer 1

The standards for CRLs specify the format of the file itself, not the filename. I have never heard of any client having issues with multiple dots in the filename - so, as long as it doesn't contain characters that the OS/filesystem can't handle reliably, there shouldn't be any issue.

As a general recommendation, you should avoid spaces and special characters in CA names, including underscores, since there are some products out there that have problems with that. So if you want the CRLs to have filenames based on the CA name, you need to remember that when creating the CAs. I've not heard of periods being a problem, but as a rule I go with "CamelCaseCANames" instead of "no.camel.case.ca.name". But this is an issue with the CA name rather than with the CRL filename.