The Dependability of Crypto Linked Off-chain File Systems in Backend Blockchain Analytics Engine

A P2P file sharing system, namely Interplanetary File Systems (IPFS) [2,3], provides a service to store huge files in off-chain local storage and partition them into pieces, for each of which with a hash code created and assigned to be posted back in blockchain for reference, referred to as crypto link. IPFS manages hash codes on blockchain in a versioned manner based on the contentaddressed distributed P2P model [4]. It is investigated in this research how to assure the efficacy of managing crypto links along with the performance of the processes with respect to the dependability of blockchain. The dependability [5] in this research is defined with reference to crypto links in a proportional manner and its performance, as referred to as the crypto speed, in an inversely proportional manner, respectively. Also note that the dependability is proportional to the cost such that the more the number of crypto links come in place, the higher its cost is. It is a standard and intuitive practice to partition a large output file into smaller pieces at a certain threshold size provided in the blockchain analytics engine (e.g., 250 KB/partition in IPFS/Hadoop). Crypto link (CL) is defined by the hash address (i.e., a pointer link) stored in the blockchain for a partition of an output file off from a backend blockchain analytics engine. Note that IPFS manages a crypto link to every partition of a file of interest whereas the proposed crypto link scheme is at a reduced number in order to address the cost and performance issue such that one crypto link to the entire file and the links between partitions within a file are maintained by local chains of links. Crypto speed (CS) is defined by the rate of the number of crypto links over the total turnaround time to encrypt all the crypto links (hash addressing) per file. Thus, notice that without loss of generality, the crypto speed increases inverselinearly along with the number of crypto links. A binomial-based [6] dependability model can be expressed as a rather straightforward function of the total number of partitions and the number of crypto links as proposed in this research. At the same time a cost model can be expressed as a function of the ratio of the number of A RT I C L E I N F O