The trend toward high processing power at a reasonable cost continues with the emergence of multi-core architectures with large number of cores. In such computing systems, a major technological challenge is to design the internal, on-chip communication network.This not only depends on high performance in latency, bandwidth, and fairness in contention under heavy loads, but also depends on an efficient authentication mechanism and protection of integrity and privacy of applications from hardware and software attacks. In this paper, we present a technique to establish secret keys for the cores employed by the same application to communicate securely. Our approach is based on key pre-distribution, in which each of the cores chooses a number of keys from a large key pool. When a group of cores are employed by an application, they discover their shared keys and establish a group key for secured communication. The key discovery and the process to connect partitioned groups use space-efficient Bloom filter to ensure the security and efficiency of the key establishment process. Our performance evaluation demonstrates the efficiency of the proposed framework.