This paper introduces a multicast method for renewing secrets which are shared by a set of hosts. The method is centralized, secure, efficient, scalable to a reasonable size and compatible with any multicast topology configuration underneath. It can be used to achieve privacy in a centralized multicast overlay. Additionally, the method can be used to renew an asymmetric key pair when a cryptosystem based on discrete logarithm is used. Knowledge of the public key is then restricted to the group it is communicated to. Security and scalability are discussed, and a comparison with other well-known alternatives is shown.