DID / Decentralized Identifier

Definition of DID: Understanding the Basics of Decentralized Identifiers

Benefits of Using DID: Why Decentralized Identifiers Are Transforming Online Identity

• decentralized: there should be no central issuing agency. DID eliminate the requirement for centralized authorities or single point failure in identifier management, including the registration of globally unique identifiers, public verification keys, services, and other information.
• persistent: the identifier should be inherently persistent, not requiring the continued operation of an underling organization;
• cryptographically verifiable: it should be possible to prove control of the identifier cryptographically;
• resolvable: it should be possible to discover metadata about the identifier.

• Control: Give entities, both human and non-human, the power to directly control their digital identifiers without the need to rely on external authorities.
• Privacy: Enable entities to control the privacy of their information, including minimal, selective, and progressive disclosure of attributes or other data.
• Security: Enable sufficient security for requesting parties to depend on DID documents for their required level of assurance.
• Proof-based: Enable DID controllers to provide cryptographic proof when interacting with other entities.                                                                                                                         
• Discoverability: Make it possible for entities to discover DIDs for other entities, to learn more about or interact with those entities.
• Interoperability: Use interoperable standards so DID infrastructure can make use of existing tools and software libraries designed for interoperability.
• Portability: Be system- and network-independent and enable entities to use their digital identifiers with any system that supports DIDs and DID methods.
• Simplicity: Favor a reduced set of simple features to make the technology easier to understand, implement, and deploy.
• Extensibility: Where possible, enable extensibility provided it does not greatly hinder interoperability, portability, or simplicity.

Syntax of DID: A Deep Dive into the Technical Structure of Decentralized Identifiers

1. the did URI scheme identifier,
2. the identifier for the DID method, and
3. the DID method-specific identifier.

DID

Methods of Implementing DID: Exploring the Different Approaches to Adopting Decentralized Identifiers

• did-key: the classic deterministic method for generating DIDs deterministically from a JWK file or other local key material
• did-web: a DID method for publishing a DID document to a domain's "/.wellknown/" configuration directory, to be resolved over HTTPS.
• did-ethr: the classic Ethereum-based DID method at the heart of uPort, Veramo, and many web3 dApp projects (implicit only; main-net indexing & resolution coming soon)
• did-ion: a DID Method implementation using the Sidetree protocol atop Bitcoin.
• did-tezos: a DID method based on Tezos accounts. 
• did-sol: the native DID method of the Solana blockchain and DeFi ecosystem.
• did:onion: a DID method designed to be resolved over Tor-style onion routing

Example of DID in Action

did-key

{
  "kty": "OKP",
  "crv": "Ed25519",
  "x": "E9yi4tOpQSCgTWNgajxGaZ0E7PlM6rvwy69mhDkxaxI",
  "d":"LtK7DbYRKjDwj-FIqwUUEI91myUj4PDzrIus9jpgUIk"
}

did:key:z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo

{
   "@context" : [
      "https://www.w3.org/ns/did/v1",
      {
         "Ed25519VerificationKey2018" : "https://w3id.org/security#Ed25519VerificationKey2018",
         "publicKeyJwk" : {
            "@id" : "https://w3id.org/security#publicKeyJwk",
            "@type" : "@json"
         }
      }
   ],
   "assertionMethod" : [
      "did:key:z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo#z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo"
   ],
   "authentication" : [
      "did:key:z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo#z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo"
   ],
   "id" : "did:key:z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo",
   "verificationMethod" : [
      {
         "controller" : "did:key:z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo",
         "id" : "did:key:z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo#z6MkfnnvXAP1KKAkfu5XfXH69oPBuFkPjSJKrwQaoybH4CHo",
         "publicKeyJwk" : {
            "crv" : "Ed25519",
            "kty" : "OKP",
            "x" : "E9yi4tOpQSCgTWNgajxGaZ0E7PlM6rvwy69mhDkxaxI"
         },
         "type" : "Ed25519VerificationKey2018"
      }
   ]
}

did-tezos

{
   "crv" : "Ed25519",
   "d" : "LtK7DbYRKjDwj-FIqwUUEI91myUj4PDzrIus9jpgUIk",
   "kty" : "OKP",
   "x" : "E9yi4tOpQSCgTWNgajxGaZ0E7PlM6rvwy69mhDkxaxI"
}

did:tz:tz1bSFkneorNU2Xsjrt9LbW2hBJBP24ZGuGv

{
   "@context" : [
      "https://www.w3.org/ns/did/v1",
      {
         "Ed25519PublicKeyBLAKE2BDigestSize20Base58CheckEncoded2021" : "https://w3id.org/security#Ed25519PublicKeyBLAKE2BDigestSize20Base58CheckEncoded2021",
         "blockchainAccountId" : "https://w3id.org/security#blockchainAccountId"
      }
   ],
   "assertionMethod" : [
      "did:tz:tz1bSFkneorNU2Xsjrt9LbW2hBJBP24ZGuGv#blockchainAccountId"
   ],
   "authentication" : [
      "did:tz:tz1bSFkneorNU2Xsjrt9LbW2hBJBP24ZGuGv#blockchainAccountId"
   ],
   "id" : "did:tz:tz1bSFkneorNU2Xsjrt9LbW2hBJBP24ZGuGv",
   "verificationMethod" : [
      {
         "blockchainAccountId" : "tezos:NetXdQprcVkpaWU:tz1bSFkneorNU2Xsjrt9LbW2hBJBP24ZGuGv",
         "controller" : "did:tz:tz1bSFkneorNU2Xsjrt9LbW2hBJBP24ZGuGv",
         "id" : "did:tz:tz1bSFkneorNU2Xsjrt9LbW2hBJBP24ZGuGv#blockchainAccountId",
         "type" : "Ed25519PublicKeyBLAKE2BDigestSize20Base58CheckEncoded2021"
      }
   ]
}

References

• https://w3c.github.io/did-core/
• https://w3c-ccg.github.io/did-resolution/
• https://w3c.github.io/did-use-cases/
• https://w3c.github.io/did-spec-registries