# NFTs for the Issuance and Validation of Academic Information That Complies with the GDPR
## 2 Preliminaries
### Smart Contracts, NFTs, and Their Role in Education  
As previously indicated, certain blockchains enable the execution of smart contracts, which are self-executing programs that automate agreements and could be used for the issuance and verification of academic certificates. These smart contracts could handle the issuance, updating, and verification of academic information in an automated and secure manner, facilitating interaction among academic institutions, students, and third parties.  
Blockchain technology, in conjunction with smart contracts, allows the creation of tokens representing specific assets from the physical or digital realms. There are three distinctive token categories:  
* Fungible tokens (based on the ERC20 standard [42]) are interchangeable with each other and lack uniqueness. Each fungible token is indistinguishable from another and can be entirely interchangeable without transferring ownership. Common examples include cryptocurrencies like Bitcoin (BTC, \(\beta\)) or Ether (ETH, \(\Xi\)), Ethereum's cryptocurrency, where each unit is identical and indistinguishable from others.
* Non-fungible tokens (commonly known as NFTs, based on the ERC721 standard [43]) are unique and indivisible, with distinctive characteristics making each one unique and not interchangeable on an equal basis with another token. NFTs are used to represent unique digital assets such as digital artworks, collectibles, or the ownership of virtual goods [44; 45]. Each non-fungible token possesses specific attributes differentiating it from similar tokens, thus its value is derived from its singularity and authenticity.  
* Semi-fungible tokens (based on the ERC1155 standard [46]) share some characteristics with both fungible and non-fungible tokens. While they are interchangeable in terms of value, they have unique properties and can hold different values within a general category. For instance, tokens representing different editions of a collectible card could be considered semi-fungible. Each card is exchangeable for another of the same type, but unique editions might have varying values.  
Within academia, extensive research has been conducted on these token categories, exploring their usefulness and applications across different fields [42; 44]. Specifically, several studies examined the introduction of NFTs into education [47]. These studies delve into how NFTs could revolutionize the issuance and verification of academic certificates by providing a unique and unalterable digital means to represent educational accomplishments. Different approaches were considered, such as storing hash data [48] through the creation of a blockchain-based school management system, named the \"Eternal Digital Certificate\" [49], using the InterPlanetary File System (IPFS) [50], a hypermedia protocol, and a distributed peer-to-peer resilient file system to tamperproof store and share information that can handle bigger file sizes; employing Decentralized identifiers (DIDs) [51] within NFTs [52] for information storage; or storing information directly on the blockchain [53]. None of these research initiatives, however, specifically addresses compliance with the GDPR.  
Moreover, NFTs, initially employed to represent unique digital assets like artworks [54], evolved into dynamic NFTs (dNFTs) capable of reflecting changes in the associated data. This adaptive and updatable information capacity could be crucial in academic information issuance, where data may require periodic modifications to remain updated and accurate in specific circumstances.