This tech note answers the question is AES 256 currently supported in the current version of PM
Do the latest versions of Performance Management support AES 256 for SNMPv3?
Currently we do not support AES 256 for SNMPv3 in the latest versions of Performance Management (2.7 and 2.8). An enhancement request had been logged to add this functionality
Enhancement Request: https://communities.ca.com/ideas/235731458