  Blockchain has been praised for its capacity to hold data in a decentralized
and tamper-proof way. It also supports the execution of code through
blockchain's smart contracts, adding automation of actions to the network with
high trustability. However, as smart contracts are visible by anybody on the
network, the business data and logic may be at risk, thus companies could be
reluctant to use such technology. This paper aims to propose a pattern that
allows the execution of automatable legal contract clauses, where its execution
states are stored in an on-chain smart-contract and the logic needed to enforce
it wraps it off-chain. An engine completes this pattern by running a business
process that corresponds to the legal contract. We then propose a pattern-based
solution based on a real-life use case: transportation of refrigerated goods.
We argue that this pattern guarantees companies pseudonymity and data
confidentiality while ensuring that an audit trail can be reconstituted through
the blockchain smart-contract to identify misbehavior or errors. This paper
paves the way for a future possible implementation of the solution described,
as well as its evaluation.

Cryptography and Security