Industry 4.0 enacts ad-hoc cooperation between machines, humans, and organizations in supply and production chains. The cooperation goes beyond rigid hierarchical process structures and increases the levels of efficiency, customization, and individualisation of end-products. Efficient processing and cooperation requires exploiting various sensor and process data and sharing them across various entities including computer systems, machines, mobile devices, humans, and organisations. Modern software-intensive Industry 4.0 systems process data with distributed and decentralized resources according to multiple organisational roles with different privileges to access and manipulate data both inside and across organisations. The ad-hoc horizontal cooperation in Industry 4.0 systems is a disruptive development that makes current privacy and trust mechanisms unsuitable as they are built around rigid hierarchical infrastructures. Trust 4.0 proposes a novel approach to privacy and trust tied to the dynamics of custom product engineering, hence, establishing privacy and trust in the ad-hoc horizontal processes.