Server apparatus, reproducing apparatus and content delivery system

Server apparatus 100a, the first generating unit 102a for generating binding information to attach straps and the said user content, the second acquisition unit 103a for acquiring the usage conditions, using the binding information and usage rule conversion title from a title key comprising second generating unit 104a for generating the key, the encrypted content using the title key, the output unit 105a to output the converted title key and the usage condition storage medium 600a. Reproducing apparatus 700a, using the use condition of the binding information and the storage medium 600a acquired from the server device 100a, the conversion title key storage medium 600a, and performs an inverse transform of the transform, generating unit for generating a decoded title key 704a, using the decryption title key, and a decoding unit 705a for decoding the encrypted contents of the storage medium 600a.