http://www.rfc-editor.org/rfc/rfc8301.txt
RFC 8301: Cryptographic Algorithm and Key Usage Update to DomainKeys Identified Mail (DKIM), S. Kitterman2018-01-01T23:00:00-00:00The cryptographic algorithm and key size requirements included when DomainKeys Identified Mail (DKIM) was designed a decade ago are functionally obsolete and in need of immediate revision. This document updates DKIM requirements to those minimally suitable for operation with currently specified algorithms.