Random key Pre-distribution scheme has been proposed to overcome the memory, computation and energy limits of individual sensor in wireless sensor networks. In this scheme, a ring of keys is randomly drawn from a large key pool and assigned to a sensor. Nodes sharing common keys can communicate securely, path-key needs to be established for those nodes who do not share any common keys. However, there is no hard security guarantee for path key set up in existing protocols. In this paper, we propose two new methods to discover multiple secure proxies and a scheme to secure path key establishment using secure proxies discovered. We show both from analysis and simulation that our scheme can achieve a high level of security against node capture based on the network parameters the user has chosen, meanwhile only incurring a small amount of overhead. All path keys established in our scheme is exclusively known by two end nodes with high probability.