Data confidentiality is one of the most important concerns in security of ad-hoc networks which have been widely studied in recent years. In this paper, we consider the public-key cryptography which is one of the simplest and viable means to maintain data confidentiality. There are several ways to distribute a public key. Flooding is an intuitive approach to distribute each node'spublic key. However, the normal flooding approach is costly, and can cause MAClevel contention in a dense region of nodes. Tree based topology flooding can be appied to mitigate these problems. The construction algorithm should use ideally only local information. In this paper, we propose a completely localized algorithm called the Local Tree-based Reliable Topology (LTRT) algorithm, which achieves both reliability and efficiency. LTRT is a localized version of TRT that has 2-edge connectivity. Each node can distribute its public key to all other nodes in the network by LTRT. Simulation results show the efficiency of LTRT and its superiority over other localized algorithms.