Establishing scalable and cross-enterprise workflow management systems (WfMSs) in the cloud requires the adaptation and extension of existing concepts for process management. This paper proposes a scalable and cross-enterprise WfMS with a multitenancy architecture. Especially, it can activate enactment of workflow processes by cloud collaboration. We do not employ the traditional engine-based WfMSs. The key idea is to have the workflow process instance to be self-protected and does not need a workflow engine to secure the data therein. Thus, the process instance discovery and activity execution can be fully independently and distributed. As a result, we can employ the data storage system, Big Table, to store the process instances, which may form a big data. The applying of element-wise encryption and chained digital signature makes it satisfy major security requirements of authentication, confidentiality, data integrity, and nonrepudiation.