A Chain of custody A chain of custody refers to documentation or paper trail, in order of time, which shows the seizure, custody, control, transfer, analysis, and disposition of evidence. means that the Blockchain Computing System A Blockchain computing system treats the Blockchain as a secure computation platform that can be shared among multiple vendors. transaction has been verified by the Overlay Networks Overlay networks are computer networks that are built on top of another network. Nodes in the overlay network are connected by virtual links. network. This happens through mining. Once a transaction is confirmed, it cannot be reversed, nor can it be double spent, which is necessary to preserve valid transactions.