rfc-7696
Guidelines for Cryptographic Algorithm Agility and Selecting Mandatory-to-Implement Algorithms
Many IETF protocols use cryptographic algorithms to provide confidentiality, integrity, authentication, or digital signature. Communicating peers must support a common set of cryptographic algorithms for these mechanisms to work properly. This memo provides guidelines to ensure that protocols have the ability to migrate from one mandatory-to-implement algorithm suite to another over time.
also
- bcp-201