{\rtf1\ansi\ansicpg1252\deff0\deflang1046{\fonttbl{\f0\fswiss\fcharset0 Arial;}} {\*\generator Msftedit 5.41.15.1507;}\viewkind4\uc1\pard\f0\fs20\par In this paper we propose a PKI architecture with high availability and resilience to mitigate the Black Hole and Spoofing attacks against ad hoc networks. The architecture is designed to reduce the amount of control messages exchanged, increasing its scalability and performance. In order to reach this goal, we propose that the various nodes within an ad-hoc network use a distributed digital certification service to authenticate and encrypt their messages. Particularly the network protocols must use the authentication and cryptography to protect the network from the above-mentioned attacks, granting confidentiality, authenticity and integrity when exchanging messages. Results show a decrease of up to 92\\% in the certificate renew protocol messages number when compared to existing approaches.\par \par Keywords: Computer system security, Computer network reliability, Public key cryptography, Wireless LAN. \par }