— In many applications of sensor networks, security is a very important issue. To be resistant against the various attacks, nodes in a sensor network can establish pairwise secret keys[5], [6], [10], authenticate all communications with cryptographic functions[8], and also apply secure information aggregation schemes[13] or hop-by-hop filtering methods[14], [16]. However, these security measures can take considerable overhead in terms of storage, communication and computation, which are scarce resources in sensor nodes. Previously proposed security measures can only resist against a limited number of compromised nodes, which we define as the resistance level. In this paper, we propose a separate solution to any security measure. This technique either significantly reduces the overhead, or increases the resistance level without increasing overhead. The solution is based on a new “Mixed Multi-Channel” (MMC) architecture. In this design, each node can only use one fixed channel....