# Blockchain and Self Sovereign Identity to Support Quality in the Food Supply Chain
## 2 Review
### DID Standards and Platforms  
We already mentioned that European countries constituted a working group to collaborate towards the realization of the ESSIF. In addition, many start-ups and enterprises are currently exploring how to implement SSI solutions. We can quote some of the most popular DID platforms, such as uPort, Sovrin and Civic, which are based on Ethereum, Hyperledger, and Bitcoin blockchain, respectively; the Bloom platform and the Ethereum standards, such as ERC735 and ERC734/ERC725 (Ref. [[https://github.com/ethereum/EIPs/issues/780](https://github.com/ethereum/EIPs/issues/780)]([https://github.com/ethereum/EIPs/issues/780](https://github.com/ethereum/EIPs/issues/780)), [[https://eips.ethereum.org/EIPS/eip-1056](https://eips.ethereum.org/EIPS/eip-1056)]([https://eips.ethereum.org/EIPS/eip-1056](https://eips.ethereum.org/EIPS/eip-1056)), [[https://github.com/ethereum/eips/issues/734](https://github.com/ethereum/eips/issues/734)]([https://github.com/ethereum/eips/issues/734](https://github.com/ethereum/eips/issues/734)), and [[https://github.com/ethereum/EIPs/issues/735](https://github.com/ethereum/EIPs/issues/735)]([https://github.com/ethereum/EIPs/issues/735](https://github.com/ethereum/EIPs/issues/735)) (accessed on 15 November 2021)) [33; 34]. _uPort_ consists of identity and messaging protocols that together form a layer of interoperable identity for the decentralized web to return ownership of the identity to the individual (see web site [[https://www.uport.me/](https://www.uport.me/)]([https://www.uport.me/](https://www.uport.me/)) (accessed on 24 September 2021) and [33; 34]. It is part of the Decentralized Identity Foundation (DIF), which is a working group created to establish a very simple, common framework for making claims about identities using different kinds of decentralized technologies, and hence, blockchain and nonblockchain technologies. uPort uses ERC1056 and ERC780 as standards. Specifically it uses ERC1056 as DID standard, and ERC780 as standard for claims registry. uPort architecture is W3C compatible, hence it complies with the universally accepted standard and allows for two types of claims: on-chain (using ERC780) and off-chain (using Json Web Tokens, JWTs) Braendgaard [35]. Any address, wallet, or identity is compatible with the ERC1056. It is not necessary to create a contract to access the benefits of the DID. _Sovrin_ is a standard for identity, solving endless passwords, insecure databases on the internet, and building a user-friendly digital identity as the analog identity, such as driver's licenses and ID cards (see web site [[https://sovrin.org/](https://sovrin.org/)]([https://sovrin.org/](https://sovrin.org/)) (accessed on 15 November 2021) and [34]. _Civic_ is an identity ecosystem decentralized, which allows the user to create the their virtual identity and store it together to personal information on the device. Verifications are made using selfie and Optical Character Recognition (see web site [[https://www.civic.com/](https://www.civic.com/)]([https://www.civic.com/](https://www.civic.com/)) (accessed on 15 November 2021)and [34]. _Bloom_ is an end-to-end protocol for proof of identity, evaluation risk and credit score so facilitating the issuing of loans. It is entirely based on blockchain (see web site [[https://bloom.co/](https://bloom.co/)]([https://bloom.co/](https://bloom.co/)) (accessed on 15 November 2021) and [34]. ERC 725/734 standard stipulates that only smart contracts can be identities. An Identity is defined implementing ERC 725/734 standard and is identified by the address of the ERC725/734 Ethereum Smart Contract. Claims instead are implemented by using ERC735 Ethereum Smart Contract and are associated to a precise ERC725/734 identity. So while ERC 725/734 incorporates everything into a single contract, uPort, which is based on Ethereum as the just quoted standards, this realizes a levels architecture in which almost any layer can be modified and updated without the need to have to update the contiguous levels (ref. [35; 36; 37; 38]).