ceph_crypto_key_prepare
ret = ceph_crypto_key_prepare(&xi->secret, client_key_usages,
ret = ceph_crypto_key_prepare(&new_session_key, ticket_key_usages,
ret = ceph_crypto_key_prepare(&au->session_key, authorizer_key_usages,
int ceph_crypto_key_prepare(struct ceph_crypto_key *key,