Namehashing is an algorithm that converts a domain name in a classical format (like www.example.crypto) to ERC-721 token id. All .crypto ecosystem contracts accept a domain name as a method argument in the form of an ERC-721 token. Namehashing is defined as a part of the EIP-137 standard. See the standard for a text description of the algorithm.

To verify an implementation of the namehash algorithm, use the following reference table:

Reverse lookup

Fundamentally, namehashing is a one-way operation. It recursively hashes the labels using the SHA-256 hash function.

If one possesses a precomputed table of all hashes and corresponding domains reverse lookups are possible. This table can be reconstructed using the events on the CNS Registry NewURI event.

JSON RPC

The .crypto registry tracks all domain names with their corresponding namehash: source code. That makes it possible to obtain an original domain name from a namehash via ETH RPC call to Registry#tokenURI.

Public API

Unstoppable Domains maintains a public-facing API which can be used to obtain domain information with a namehash. To do this, call https://unstoppabledomains.com/api/v1/{namehash}

Example request:

$ curl https://unstoppabledomains.com/api/v1/0x0f4a10a4f46c288cea365fcf45cccf0e9d901b945b9829ccdb54c10dc3cb7a6f

Example Response:

{
  "addresses": {},
  "whois": {},
  "ipfs": {},
  "gundb": {},
  "social": {},
  "meta": {
    "owner": "0x000000000000000000000000000000000000dead",
    "type": "CNS",
    "ttl": 0,
    "domain": "crypto",
    "namehash": "0x0f4a10a4f46c288cea365fcf45cccf0e9d901b945b9829ccdb54c10dc3cb7a6f"
  },
  "records": {}
}