Your documents are not uploaded, only the hash will be integrated into the blockchain. Nous ne pouvons voir vos documents, ni même vous connaître.
The hash function used is SHA256. Nowadays, it is considered unfalsifiable. Nobody is able to provide a document generating the same hash as your file.
Submit a file is trivial. A simple drag & drop is enough. Registration requires blockchain in the transaction, which will be charged only few mBTC