We are looking this up for you. We'll reply back as soon as we have an answer.
Based on a conversation I had with the Mellanox team, encryption for native IB, nor for RoCEv1 is not a standard (yet); None of the organizations chose to pick up the challenge yet. Typically, Mellanox promotes and involve in implementing standard protocols for bringing the best out of user’s requirements and the community collaboration.
Hope this helps.