Glossary
Email authentication
Canonicalisation
The normalisation applied to headers and body before hashing. "simple" tolerates almost no change; "relaxed" tolerates whitespace and header-case differences, which is why relaxed/relaxed survives more intermediaries.
Defined in RFC 6376 §3.4.
Where this appears
The lessons that use this term, and what each is for.
Email Authentication FundamentalsAnatomy of a DKIM-Signature headerRead a DKIM-Signature header and say which domain is making the claim and which headers it covers.DKIM PractitionerDKIM-Signature, tag by tagRead any DKIM-Signature header and state what each tag contributes to the verification.DKIM PractitionerRelaxed and simplePredict which whitespace and header changes each canonicalisation survives.DKIM PractitionerWhat breaks a signature in transitName the intermediary responsible when a signature that was valid at send fails at delivery.DKIM Practitionerbody hash did not verifyIdentify what modified a message from the fact that only the body hash failed.