*5.4. Trust*

Blockchains are trust engines in an inherently trustless M2X Economy collaboration context. Blockchain technology promises to secure the M2X ecosystem where the managemen<sup>t</sup> of large and distributed datasets in a secure way is essential. Still, the expected performance and scalability of existing blockchains is currently not compatible for a M2X context [56]. Consequently, new types of blockchains with novel consensus and validation algorithms are required for the large number of securely connected smart autonomous devices that interact with other machines, humans, and infrastructure.

Since M2X ecosystems are a source of large, unstructured data sets that must be combined and understood to extract intelligence with advanced analytic for actionable decision-making, it is our contention that trust managemen<sup>t</sup> is only possible with novel blockchain technology of high scalability and performance. For example, the use of blockchains in a M2X ecosystem involves many devices that have low storage capacity and computing power. Since these devices cannot maintain a blockchain of many gigabytes, novel sharding managemen<sup>t</sup> for blockchain parts to and from devices is required to overcome storage and computing-power limitations [1,57].
