# A Non-Fungible Token Solution for the Track and Trace of Pharmaceutical Supply Chain
## 4 Web3 Serialization with Blockchain and Non-Fungible Tokens  
The traceability and serialization process discussed in the previous section contains many technological and governance issues that are summarized below:  
_- Data retention_: all the actors of the supply chain have to keep and maintain the information about the product for many years. On the one hand, this is certainly true for the producers that have responsibility over the electronic batch record, which contains the data of production, and on the other hand, the warehouse and the retailers also have the duty to append information about the status of the package (for instance, if products get damaged or compromised). In any case, this turns into a responsibility to guarantee the final customer. _- Data synchronization_: along with data retention, another important duty of the supply chain actors is to synchronize the status of the product with the central authority. This is a relevant activity that increases success in guarding against counterfeiting because the central authority can monitor the responsible actor of the package in any step of the distribution network. _- Ownership_: this concept is tightly linked to the responsibility that each actor owns during the handling of the package in each step of the distribution network. In this sense, the responsible actor has to update the status of the product in order to guarantee the integrity of the distribution process. _- Immutability_: the data characterizing any package (and its content) must not be manipulated and must describe only the information of traceability that has been appended to the product by the actor of each step of the distribution network. With the technological infrastructure discussed in Section 3, the previous requirements are only partially tackled because in most of the current distribution networks, synchronization and verification with the central authority only occurs when the product enters in the distribution network. Potentially, before a product is dispensed to a patient (hospital, etc.) or to a consumer (pharmacy), a verification check should be performed so as to guarantee that the GTIN and the unique serial number of the item's packaging are valid and have been uploaded in the central authority's database by the real manufacturer of the product. Moreover, if the ability to synchronize the status of the packaging could occur at any step of the distribution network, the value of the traceability process could increase tremendously with incredible benefits for all stakeholders, including the patients. Unfortunately, this scenario is much more challenging because it would require a common software layer for each supply chain actor that, when integrated at the level of their information system (such as their ERP), offers the ability to communicate and synchronize with the central authority automatically. Blockchain technology has key features that solve the previous issues [82] and, with the cutting-edge tools of Web3, there is a room to increase the adoption of a decentralized paradigm and, by this, improve the traceability process and simplify the integration among the actors of the distribution network. In order to interact with the blockchain (and related smart contracts), users have to operate by means of public and private keys that allow the basic operations of signing and retrieving information. The private key, also known as the secret key, is a variable in cryptography that is used with an algorithm to encrypt and decrypt data. It is personal and must not be given to anyone, otherwise all of the owner's assets in the blockchain can be stolen. Moreover, it allows the creation of multiple public keys that can be used as a public identity (i.e., public address) to operate with other entities. What Web3 offers is a common software layer for web-based applications (web apps) and digital wallets that simplifies the interaction with the blockchain by also assigning private and public keys (and the related public addresses).