# At the Nexus of Blockchain Technology, the Circular Economy, and Product Deletion
## 2 Background
### Blockchain Technology  
A potential breakthrough for future supply chains can be adopting technological disruptive innovations such as blockchain technology. Information sharing is an urgent requirement in supply chains; especially with greater interest of digitization and Industry 4.0 developments [15; 16]. Information can connect dispersed entities, facilitate better relationships in supply chains, prevent fraud and falsification, and reduce risks. However, tracing information through a complex supply chain network is a challenge. Blockchains can support information sharing in supply chains, link stand-alone systems, and provide real-time data to all stakeholders. Blockchain technology records information through decentralized ledgers [17; 18]. Ledgers are visible to all actors involved in transactions including supply chain partners [19]. Ledger transactions have cryptographic time stamping that elevates the security of information [20]. In this way, the blockchain allows customers to inspect the uninterrupted chain of custody and transactions from the raw materials to the end sale. This information is recorded in ledgers as transactions occur on these multiple blockchain information dimensions; with verifiable updates. For example, end customers can rely on the authenticity of valuable goods by tracing them to their origin [21]. Blockchain technology can benefit supply chain provenance and sustainability. A blockchain application that is connected with radio frequency identification (RFID) [22], Internet of Things (IoT) [23; 24], and global position sensors (GPS) [25] can collect accurate data and address traceability issues in supply chains. High levels of transparency, verifiability, immutability, and reliability of data provided by blockchain can facilitate information flow among complex supply chain networks and stakeholders [26]. The immutability feature arises from the append-only concept of blockchain ledgers where a recorded transaction cannot be changed or altered without blockchain network consensus. This characteristic strengthens the reliability of blockchain information. Decentralized ledgers reduce the need for trust based on third-party transaction verification; shedding intermediaries from transactions [27]. Blockchain technology effectively supports updated tracking in the supply chain. Information related to the sources of materials, product supply chain journey, and participating actors in purchasing, producing and distributing products can each be presented on a blockchain platform; while maintaining visibility to supply chain network participants. Supply chain members may verify transactions and vote to maintain some trustworthiness in records. A key element of blockchain technology is a smart contract, sometimes reflecting real-world contracts in a digital way. Smart contracts contain codes of agreements between parties, monitor conditions, and execute the embedded functions [28]. Smart contracts shift the need for traditional legal third parties to network consensus. Automatic execution of trigger points and digital records of regulations and business logic can increase efficiency and reduce transaction costs [29]. Smart contracts can also be utilized for supply chain process management and even process reengineering. Permissionless (public) and permissioned (private) are two types of blockchain that deal with the openness of the platform. A permissionless blockchain allows anonymous users to interact with the system. Bitcoin and cryptocurrencies are examples of permissionless blockchains. Alternatively, permissioned blockchains limit information access to recognized users [30]. For example, IBM and Maersk have developed a permissioned blockchain that included a defined group of participants to trace information in the supply chain. Although the permissioned blockchain allows companies to control who can access critical information, the appropriate level of openness and information sharing is still debatable.