In this paper, we propose a novel security scheme with key recovery capability for mobile communications. The proposed key recovery mechanism offers a “backdoor” for an authorized agency to monitor suspected communications while protecting legal users from unauthorized disclosure of their data privacy. All the features form a unitary security scheme with monitoring service. The performance analysis shows that our scheme has a low-computational complexity and it can be practically deployed on contemporary mobile devices. Copyright © 2009 John Wiley & Sons, Ltd.