  The blockchain technology has been changing our daily lives since Bitcoin -
i.e., the first decentralized cryptocurrency - was invented and released as
open-source software by an unidentified person or a group called Satoshi
Nakamoto in 2009. Of many applications which can be implemented based on the
blockchain, storage is an important one, a notable example of which is the
InterPlanetary File System (IPFS). IPFS is a distributed web based on a
peer-to-peer hypermedia protocol to make the web faster, safer, and more open
and focuses on public accessible files. To provide a solution for private file
storage in the blockchain way, in this paper we propose a Merkle-tree-based
File System (MTFS). In MTFS, the blockchain is more than a trust machine; it is
an abstract of a cluster system. Distributed random nodes form a tree network
cluster without a central controller to provide a secure private storage
service and faster message propagation. Advance proxy re-encryption algorithm
is applied to guarantee secure file exchanges under permission. Merkle tree
will make sure that the files are distributed among the service nodes in a
balanced way. The proposed MTFS can be used not only for personal file storage
and exchange but also for industry requiring mutual trust in file uploading and
downloading in making contracts like insurances.
