Community-based de-duplication for encrypted data

Technologies for de-duplicating encrypted content include fragmenting a file into blocks on a computing device, encrypting each block, and storing each encrypted block on a content data server with associated keyed hashes and member identifications. The computing device additionally transmits each encrypted block with an associated member encryption key and member identification to a key server. As part of the de-duplication process, the content data server stores only one copy of the encrypted data for a particular associated keyed hash, and the key server similarly associates a single member encryption key with the keyed hash. To retrieve the file, the computing device receives the encrypted blocks with their associated keyed hashes and member identifications from the content data server and receives the corresponding member decryption key from the key server. The computing device decrypts each block using the member decryption keys and combines to blocks to generate the file.