Distributed-hash-table (DHT) has been proposed to solve the problem of scaling for P2P networks. However, there are some problems of security in P2P networks. One of the problem is that key exchange is not performed preventing against endangering security. This reason may be the fact that P2P networks have no trusted server. Although certification and authentication are able to protect key exchange from spoofing and man-in-the-middle attacks, these cannot be applied because of that. Therefore, an attacker can easily compromise key exchange since P2P networks should accept any node whether it is malicious or not, and every node of P2P networks plays a role of router. Until today, for the above reasons, there is no way to exchange the secret key on P2P networks protecting against encountering security. In this paper, we will propose a key exchange method on P2P networks protecting against spoofing and man-in-the-middle attacks. For the purpose of protecting key exchange from encountering security, we will present the enhanced routings which are directional and probabilistic routings.