Reef Namespace - Chains

Author Boo 0x
Status Draft
Type Standard
Created 2023-06-30
Requires CAIP-2


For context, see the CAIP-2 specification.


The namespace is called “reef” to encompass all chains of the Reef ecosystem. This includes a production network and one or more test networks.

The rationale behind the use of block hash from the genesis block stems from its usage in the Reef architecture to secure network consensus.


The definition for this namespace will use the genesis-hash as an identifier for different Reef chains. The format is a 32 character-long lowercase hexadecimal string, without the 0x prefix, representing the first half of hash of the 0 block (genesis block) for a given chain.

As CAIP-2 references for this namespace are 32-byte hashes in lowercase hexadecimal, they can be validated with the simple regular expression: [0-9a-f]{32}

Resolution Method

There is no index or registry that maps genesis hashes to networks, and defining such a mechanism for doing so is out of the scope for this specification. This specification assumes that consumers of this class of CAIP-2 identifiers are able to properly resolve them to the appropriate network. This specification then defines how to verify that a given RPC node, reachable via a regular URL, belongs to a given Reef network.

Given the URL of a Reef network RPC node, make a JSON-RPC request to the node with method chain_getBlockHash, for example:

// Request
  "id": 1,
  "jsonrpc": "2.0",
  "method": "chain_getBlockHash",
  "params": [0]

// Response
  "id": 1,
  "jsonrpc": "2.0",
  "result": "0x7834781d38e4798d548e34ec947d19deea29df148a7bf32484b7b24dacf8d4b7"

The response will return as a result the hash of the block with height 0 (i.e., the genesis block). The leading 0x and the last 32 characters will need to be trimmed, such that the resulting string is a 32-character Hexadecimal string (i.e., 16 bytes) that represents the Reef network in which the RPC node participates.

Test Cases

This is a list of manually composed examples:


Reef Mainnet


Reef Scuba testnet



Copyright and related rights waived via CC0.


Please cite this document as:

Boo 0x, "namespaces/reef-caip2: Reef Namespace - Chains [DRAFT]," Chain Agnostic Namespaces, reef-caip2, June 2023 / . [Online serial]. Available: