Abstract: Securely storing assets in a cloud computer storage service. Preparation to store assets for a user may comprise determining a location to store the assets, generating a write access signature, and sending the determined location and the signature to the user. A request is received from the user to store the assets. Such a request includes the assets, the location, and the signature. In response to receiving the request, a determination is made regarding the write access signature whether the request should be honored. When the request is honored, the assets are stored in the determined location and the write access signature is invalidated. Upon subsequent user requests to access the assets, short-term read access signatures are generated and provided to the user. The assets are written once per generated write access signature and reads are to be performed close in time to when short-term read access signatures are requested.