As deployment of multiple sensors for a single measurement comes with an increasing cost we propose to deploy multiple sensors over what we define as correlation area The idea is that off-chain measured data are correlated according to a certain statistical correlation model Therefore once the correlation model has been inferred a value claimed by a sensor can be trusted if the correlation computed from other sensors is above a certain level To enforce fault tolerance and defence against byzantine nodes we propose to query a randomly selected subset of the available nodes in the correlation area As random selection is introduced the only way an attacker can control data inserted in the smart contract is to control the majority of sensors A multi-signature scheme is hence introduced where oracles sign their contribution if a certain correlation level is obtained We also propose to reward proper behaviour of sensor nodes with assets that they are allowed to spend