Authentication-Results Registration for Differentiating among Cryptographic Results
This memo updates the registry of properties in Authentication- Results: message header fields to allow a multiple-result report to distinguish among one or more cryptographic signatures on a message, thus associating specific results with the signatures they represent. [STANDARDS-TRACK]
Normative requirements
Every sentence in this RFC carrying an RFC 2119 keyword, with the section it came from. 3 must, 1 should, 0 may.
4 Definition
- MUSTThe value associated with this item in the header field MUST be at least the first eight characters of the digital signature (the "b=" tag from a DKIM-Signature) for which a result is being relayed, and MUST be long enough to be unique among the results being reported.
- MUSTWhere the total length of the digital signature is fewer than eight characters, the entire signature MUST be included.
- MUSTMatching of the value of this item against the signature itself MUST be case-sensitive.
- SHOULDIf an evaluating agent observes that, despite the use of this disambiguating tag, unequal authentication results are offered about the same signature from the same trusted authserv-id, that agent SHOULD ignore all such results.