In order to access resources within a peer-to-peer network, JXTA completely relies in the usage of advertisements published by the resource owner. This may easily lead to DoS or spoofing attacks from malicious peers by forging advertisements with false identifiers unless advertisement authenticity is pro- vided. Furthermore, in a fully distributed environment, in order to truly isolate a malicious node, collaboration is necessary from other peers. For that reason, it must be possible to prove to other parties that a peer is being disruptive. This paper presents a method that provides authenticity and non-repudiation to JXTA advertisements. This scheme is fully distributed and based in a pure peer-to-peer model, not requiring the arbitration of a trusted third party or a previously established trust relationship between peers, which is one of the main challenges under this kind of environments.