The development of complex systems involves many organizations that work together to describe a system using artifacts. These artifacts are developed collaboratively, but may contain intellectual property. The intellectual property must be protected from the other contributing organizations. Nonetheless, the artifacts have to be exchanged in order to work collaboratively. Therefore, we propose our new idea, the deltachain. The deltachain uses encrypted deltas, i.e., arbitrary changes made to an artifact, that are stored on a chain. This deltachain can be used as a single source of truth for the whole system. The encryption makes it possible to exchange the deltachain on untrusted third-party hardware. To access the collaboratively developed artifacts, an organization accesses the encrypted deltachain, decrypts the deltas it has access to, and can work with the artifact. The changes performed by the organization are then converted to encrypted deltas and appended to the deltachain.