"So how does Storj work? The application takes the files you'd like to store on someone else's hardware and encrypts them -- that is, it scrambles them using cryptographic techniques so that only someone in possession of a specific key can render them readable again. It then shards the files, meaning that it splits (and occasionally combines) them into fragments of uniform size. These are divvied up among different nodes for storage, so that a given file might be stored across a few continents."
The project’s code is open source, so anyone could implement an instance of Storj. That said, Storj Labs, the private company behind Storj, has already built an impressive network. Users pay for access to that network.
The Storj architecture follows the standard model of sharding, encryption, and swarming described above to split and re-compile files."