Namehashing

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:

Domain Name

ERC721 Token

.

0x0000000000000000000000000000000000000000000000000000000000000000

crypto

0x0f4a10a4f46c288cea365fcf45cccf0e9d901b945b9829ccdb54c10dc3cb7a6f

example.crypto

0xd584c5509c6788ad9d9491be8ba8b4422d05caf62674a98fbf8a9988eeadfb7e

www.example.crypto

0x3ae54ac25ccd63401d817b6d79a4a56ae7f79a332fe77a98fa0c9d10adf9b2a1

a.b.c.crypto

0x353ea3e0449067382e0ea7934767470170dcfa9c49b1be0fe708adc4b1f9cf13

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": {}
}