With the development and maturity of cloud computing technology, the demand for cloud storage is growing. Deduplication is a basic requirement for cloud storage to save storage space of cloud servers. And as clients are untrusted from the perspective of the server, the notion of Proofs of Ownership (PoWs) has been proposed in client-side deduplication. On the other hand, the clients cannot completely trust the server either, thus clients have to know whether their files are stored integrally in the cloud. However, most existing works only focus on one-way validation. In this paper, we introduce a framework called Proofs of Ownership and Retrievability (PoOR) considering the requirement of mutual validation. In our PoOR scheme, clients can prove to the server their ownership of files and verify the retrievability of the files without uploading or downloading them. For ensuring the recoverability and security of files in server, we encode files by erasure code. In order to keep the communication cost in constant, we employ Merkle Tree and homomorphic verifiable tags which also induce acceptable storage overheads. At last, we implemente our scheme and compare it with other schemes. The result shows that the PoOR scheme is efficient in computation performance, especially when the size of the file is large.