RISE AB RISE AB Object Security for Constrained RESTful Environments (OSCORE) uses AEAD algorithms to ensure confidentiality and integrity of exchanged messages. Due to known issues allowing forgery attacks against AEAD algorithms, limits should be followed on the number of times a specific key is used for encryption or decryption. Among other reasons, approaching key usage limits requires updating the OSCORE keying material before communications can securely continue. This document defines how two OSCORE peers must follow these key usage limits and what steps they must take to preserve the security of their communications. Also, it specifies Key Update for OSCORE (KUDOS), a lightweight procedure that two peers can use to update their keying material and establish a new OSCORE Security Context. Accordingly, it updates the use of the OSCORE flag bits in the CoAP OSCORE Option. Finally, this document specifies a method that two peers can use to update their OSCORE identifiers, as a stand-alone procedure or embedded in a KUDOS execution. Thus, this document updates RFC 8613.