  We propose a blockchain-based solution for enabling verifiability of
manufacturing processes. We base our solution on the methodology of verifiable
computing which, originally developed for cloud computing, enables clients to
outsource computations to more powerful servers without the need to trust that
the server correctly performed desired computation. Verifiable computing
accomplishes this by enabling the client to generate cryptographic objects that
the server must use to produce a cryptographic proof that verifies the
correctness of results. The black box nature of servers in cloud computing is
analogous to that of the manufacturing processes of an upstream manufacturer.
In this work, we develop a one-to-one correspondence between physical processes
and their digital representations as state sequences which is needed for the
implementation of verifiable computing. Because direct application of
verifiable computing in this case would be computationally prohibitive, we
introduce a blockchain to provide a computationally feasible methodology for
verifiable computing applied to physical processes. We implement and show the
results of our implementation on a proof of concept, developed on Hyperledger
Fabric.
