The distributed content-addressed data storage layer is responsible for providing a very simple read/write storage interface: agents, voluntarily, elect to store data blobs, content-addressed by hash. Agents can ask other agents to retrieve data with a
StorageRead call, providing the hash, and agents can ask other agents to store data with a
StorageWrite call, providing the data as a binary blob, where the address at which to store the data is calculated with the standard
hash. Upon retrieving data with a
StorageRead call, agents can check that they received the correct data by checking that
hash(data) is equal to the address they requested data for.
data StorageReadMessage = StorageReadMessage Hash
data StorageWriteMessage = StorageWriteMessage ByteString
Storage read and write requests are optionally signed - the signature is not required for data integrity, but it may be useful for anti-DoS and proof-of-retrievability.
For now, this layer does not deal with erasure coding, data storage incentives, or other sharding/scaling schemes. The entanglement graph information may be sufficient for highly entangled agents to safely store a certain amount of data for each other for free (and this is very efficient as compared to more complex schemes). Future versions of the storage layer can support erasure coding schemes "under the hood" of this basic interface, allow nodes to automatically store data for untrusted agents who pay them with some sufficiently valuable token, and perform more complex operations under the hood, but the basic interface from the perspective of other layers should be able to remain roughly consistent with this very simple model.
This data storage layer intentionally does not feature any sort of access control or privacy semantics - data which is expected to be kept private should be encrypted before it is stored on the storage layer, and we rely on the encryption to provide privacy to the appropriate parties. It may sometimes be helpful for data to be automatically deleted "by default" after awhile - this can be achieved in the incentive case by ceasing payment, and in the high-entanglement case by internally tracking which agent(s) requested data to be stored and deleting it at their request.
Storage is generally unordered and observations of storage operations performed are mostly not expected to be included in the physical DAG, although they can occaisionally be if certain nodes wish to track metadata.