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Ethereum Registration Authority

Ethereum Registration Authorities (ERA) are entities which operate Ethereum smart contracts which link organizations' blockchain identities, domain names and real world identities. Domain names are linked to Ethereum accounts via smart contracts. The linkage to real world identities is done by the ERAs completing Know Your Customer (KYC) audits of organizations prior to listing them.

A key aspect of the ERA system is that organisations control their own information. They can update their own information when and as they see fit. They can choose to list with any or all root registration authorities, or become a root registration authority themselves.

Applications that wish to use the ERA system choose which ERAs they trust. The are able to iteratively search through delegate ERAs to find the domain specific information they need.

Example Usage

The diagram below shows an example of contracts used in the Ethereum Registration Authority system.

alt text

In the example, there are two root registration authorities, A and B. Root ERA A has an entry for is also listed in root ERA B. As such, applications which need to access information about or any of its sub-domains could use
Root ERA A or Root ERA B. operates a delegate ERA contract. It has two sub-domains listed and The entries for each sub-domain point to separate DomainInfo contracts which hold the domain specific information. is only listed in Root ERA B and does not operate a delegate registration authority. Its entry in Root ERA B points directly at the DomainInfo contract for operates a delegate ERA. It has a sub-domain listed. This sub-domain indicates the delegate ERA for its sub-domains is the ERA. As such, and are listed in the ERA. Alternatively, a the sub-domains and/or could have been listed in a separate delegate ERA. Doing this would allow control of the sub-domains to be handled by a different group within, such as a separate business unit. Both sub-domains and use the same DomainInfo contract to store their domain information. could map to a government department of education that operates a Delegate ERA. Each university, for example University of Queensland would operate their own Delegate ERA, for example The university could delegate the configuration of the Domain Information contracts to the departments within the university. As such, the administrators responsible for the domain would operate their own DomainInfo contract.

An application could use the Finder contract (not shown in the example) to resolve domain names to determine the DomainInfo contract to use for each domain.

Expected Usage

The initial usage is envisaged as to be used for bootstrapping sidechains for use in permissioned networks. This technology could be used for any situation in which blockchain information needs to be tied to a domain name, each domain name holder should be able to control their information, and where a central root registration authority is not desirable.

Details of Contracts


There are three sets of contracts:

  • EthereumRegistrationAuthorityInterface and implementation(s): Root and delegate ERA.
  • DomainInfoInterface and implementation(s): Key - value map of domain specific data.
  • FinderInterface and implementation(s): Domain name resolver.

Each set of contract has an interface which applications should use. Implementations all return version numbers. It is anticipated that there may in the future be new functions added. Applications should be written such that they fetch the version number to understand which functions have been implemented.

Ethereum Registration Authority Interface

There are two main transaction functions:

  • addUpdateDomain: Add or update the domain entry. Only the ERA contract owner can add a new domain listing. Only the domain owner can update a domain listing.
  • removeDomain: Remove a domain entry. Only the ERA contract owner can remove a domain listing.

These functions and the getter functions take a domain hash. The domain hash is calculated as:

```Domain Hash = Kecak256(domain name)```

The following information is stored for each domain entry:

  • Domain Authority: The address of the ERA contract which manages sub-domains, if such a delegate ERA exists for the domain.
  • DomainInfo: Address of DomainInfo contract if such a contract exists for the domain.
  • Domain Owner: The owner of the domain entry.

Domain Info Interface

The DomainInfo contract holds a map of key - value pairs. Keys are the message digest of the raw key. Raw keys are the domain names they pertain to followed by the key type. That is:

```keccak256(domain name, ":", key type)```

The domain name is the full domain name ("") or the special wild card domain ("*"). Keys which use the wild card provide default values for all domains in this Domain Information contract.

The key type is either a value defined below or a user defined values. To avoid name collision, user defined keys should be prefixed using reverse domain name ordering for the domain which creates the key.

Defined Keys Expected Value and Value Format
dns.a IPv4 address as described in RFC 1035:
dns.aaaa IPv6 address as described in RFC 3596:
dns.txt Text strings as described in RFC 1035:
ef.enode Enode address in ASCII as described here: Public encryption key / key agreement key for the Enterprise Ethereum node. The maximum number of nodes in a sidechain cluster. Domain names for the cluster are expected to be named sc0.domain to sc(size-1).domain. Email address to use to contact the owner of the domain.

The table below shows the example keys.

Example Key Description
keccak256( The IPv4 address for
keccak256(* The maximum number of nodes in the sidechain cluster for
keccak256( The enode address of node
keccak256(* The email address to be used to contact the owner of the DomainInfo instance.


To be completed.