Mechanisms for coordination and synchronization, like shared counters and distributed queues, are used in the development of many distributed systems. These mechanisms are implemented on top of coordination infrastructures, such as tuple spaces. A recent study showed that extensibility is fundamental for performance: the main idea is to allow the servers supporting the coordination infrastructure to access and process coordination information, consequently, it is not necessary to transfer information to clients or to reprocess requests due to concurrency. Unfortunately, existing proposals for extensible distributed coordination do not provide security and privacy once servers must access data in plaintext. This work proposes the use of robust cryptographic schemes, recently integrated into DEPSPACE, to develop secure protocols for extensible coordination. Experiments show that the proposed solutions significantly improve system performance.