Ad hoc networks offer novel capabilities in the mobile domain widening the mobile application field and arousing significant interest within mobile operators and industrials. Securing routing protocols for ad hoc networks appeared soon as a challenging scope for industrials and researchers’ community, since routing protocols, base of ad hoc networks, haven’t defined any prevention measure or security mechanism in their specifications. In this paper, we propose a securing solution providing the integrity of the OLSR routing messages while respecting ad hoc routing protocols characteristics and operation. The solution relies on a distributed securing scheme based on threshold cryptography features and which completely fits to the OLSR operation. Implementation proves finally the successful operation of the security model and show that additional delay is suitable to OLSR routing specifications.