Skip to content

W3C DID-Scheme

A DID-Scheme is the formal syntax of a Decentralized Identifier.

Tyron DID-Scheme

It is a URI scheme conformant with RFC3986, Uniform Resource Identifier (URI): Generic Syntax.

The following is the ABNF definition using the syntax in RFC5234, "Augmented BNF for Syntax Specifications: ABNF":

Generic rule names not defined there, are defined in RFC3986.

did                     = "did:" method-name ":" method-specific-id

method-name             = 1*method-char

method-char             = %x61-7A / DIGIT

method-specific-id      = *( *idchar ":" ) 1*idchar

idchar                  = HEXDIG

HEXDIG                  = DIGIT / "a" / "b" / "c" / "d" / "e" / "f"

DIGIT                   = %x30-39

Both the scheme identifier (did) and the method name MUST be an ASCII lowercase string.

The tyronZIL DID-Method defines its method-name as "tyron" and the method-specific-id syntax as hierarchically partitioned:

method-name             = "tyron"

method-specific-id      = blockchain-namespace ":" network-namespace ":" did-suffix

blockchain-namespace    = "zil:"

network-namespace       = "main:" / "test:"

did-suffix              = 1*idchar

Example of a Tyron DID:

did:tyron:zil:test:0x5a156a1d18a9a76a0a86b62fcdcb2e547173f3c9

DID-Suffix

The DID-Suffix MUST be globally unique. A Tyron DID-Suffix is the Zilliqa hex-encoded address of the corresponding DID-Smart-Contract (DIDC).

Every Zilliqa address is unique. As explained in Zilliqa's white-paper, the "address for a contract account is computed from the address of its creator and how many transactions the creator account has sent, aka account nonce":

contract_address = LSB160(SHA3-256(address||nonce))

where:

  • LSB160() returns the rightmost 160 bits of the input;
  • SHA3-256() is the SHA-3 hash function that produces 256-bit digests;
  • address is the address of the creator account; and
  • nonce is the creator’s nonce value.

Implementation

The Tyron DID-Scheme gets implemented by the DidScheme procedure of the DIDC that generates the Decentralized Identifier and its Tyron Hash.

On testnet:

procedure DidScheme()
    this_did =
        let did_prefix = "did:tyron:zil:test:" in
        let did_suffix = builtin to_string _this_address in
        builtin concat did_prefix did_suffix;
    decentralized_identifier := this_did;
    this_th =
        let hash = builtin sha256hash this_did in
        builtin to_bystr hash;
    th = Some{ByStr} this_th;
    tyron_hash := th
end

Normalization

  • The DID-Scheme name (did) MUST be lowercase.
  • The DID-Method name (tyron) MUST be lowercase.
  • Tyron's specific-id MUST follow the rules stated above.

Persistence

A Tyron DID is bound exclusively and permanently to a single subject, known as the contract_owner, even after deactivation.