Making backup is so cumbersome and expensive that individuals hardly ever backup their data and companies usually duplicate their data into a secondary server. This paper proposes a novel Peer-to-Peer (P2P) backup system known as the SecureBackup service, which was defined in the DisPairse research project. It utilizes the unused personal hard disk spaces attached to the Internet to implement a distributed backup service that is reliable, performant, and secure. Additionally to the existing approaches like pStore [Batten et al. 2001], Pastiche [Landon et al. 2002], and PeerStore [Landers et al. 2004], addressing the integrity, confidentiality and availability of data in a P2P backup system, the SecureBackup service implements the access control of the peers to the service, the detection of malicious peers, the evaluation of the reliability level of each peer, the rewarding or charging of the peers for theconsumed resources or the resources they made available, and the incentives for peers to actively participate to the service.SecureBackup is mainly characterized by a newly meta-data structure for backup file, and a centralized node, under the controlof the service provider, which supervises the Authentication, Authorization and Accounting (AAA) services and the operationsof the system. While designing a centralized architecture, we paid attention to preserve the autonomy of the P2P backup service.According to some experiments made on few peer nodes, we are confident that the introduced security mechanisms do not muchpenalize the performances of the system.