Add lint to check for NULL parameters in the AlgorithmIdentifier element of CRLs, when mandatory per RFC 4055#1040
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christopher-henderson merged 5 commits intoMay 10, 2026
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Thank you for this lint!
It's not easy when cryptobyte has to be whipped so that you can manually walk through the structure. So your work is very much appreciated.
| // Attempt to read the parameters element | ||
| var nullBytes cryptobyte.String | ||
| var nullFound bool | ||
| if !signatureAlgorithmBytes.ReadOptionalASN1(&nullBytes, &nullFound, asn1.NULL) { |
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-- Pointless Commentary --
cryptobyte is both very useful and very clearly a C library pretending to be Go library 😆
I have to reckon that these are 1:1 translations, minus the fact these are methods on a *String rather than functions that take in a *String.
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Suspicious of a recent incident, I noticed that Zlint lacks a certain check on the signature algorithm identifier of CRLs. Specifically, it lacks verification that — when the signature algorithm is one of the four
shaXXXWIthRSAEncryptionalgorithms (with XXX being one of 224, 256, 384, 512) — the mandatoryparameterselement is present and set to NULL, as required by RFC 4055 Section 6 (which is referenced by RFC 5280). A similar check already exists for certificates, but not for CRLs, so here's my proposal. In my lint, I perform this check on the outer AlgorithmIdentifier. I think examining the inner or the outer one is equivalent, since the two are supposed be identical (and if they aren't, it's a different problem that IMO should be addressed by a separate lint).