This paper focuses on the resilience of routing protocols against malicious insiders willing to disrupt communications. Previous study showed that introducing randomness and data replication enhances the resilience of routing protocols. It makes them unpredictable for an attacker and provides route diversification. We propose a theoretical framework of the resilience based on biased random walks on a torus lattice. The objective is to evaluate analytically the influence of bias and data replication introduced to random walks. The bias allows to decrease the route length, thus reducing the probability of a data packet to meet a malicious insider along the route; however, it also decreases the degree of randomness (entropy). When combined with data replication, the reliability is improved thanks to route diversity despite an additional overhead in terms of energy consumption. The main goal is to provide a good tradeoff between shortest path and route diversity for a reasonable cost.