6.6 KiB
description: Pantheon Clique Proof-of-Authority (PoA) consensus protocol implementation path: blob/master/config/src/main/resources/ source: rinkeby.json
*[vanity data]: Signers can include anything they like as vanity data.
Clique
Pantheon implements the Clique Proof-of-Authority (PoA) consensus protocol. Clique is used by the Rinkeby testnet and can be used for private networks.
In Clique networks, transactions and blocks are validated by approved accounts, known as signers. Signers take turns to create the next block. Existing signers propose and vote to add or remove signers.
Genesis File
To use Clique in a private network, Pantheon requires a Clique genesis file. When connecting to Rinkeby,
Pantheon uses the rinkeby.json
genesis file in the /pantheon/config/src/main/resources directory.
A PoA genesis file defines properties specific to Clique:
!!! example "Example Clique Genesis File"
json { "config":{ "chainId":1981, "constantinoplefixblock": 0, "clique":{ "blockperiodseconds":15, "epochlength":30000 } }, "coinbase":"0x0000000000000000000000000000000000000000", "difficulty":"0x1", "extraData":"0x000000000000000000000000000000000000000000000000000000000000000001a54556254bfa3db2daa7673435ec63649925c50000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", "gasLimit":"0xa00000", "mixHash":"0x0000000000000000000000000000000000000000000000000000000000000000", "nonce":"0x0", "timestamp":"0x5c51a607", "alloc": {}, "number":"0x0", "gasUsed":"0x0", "parentHash":"0x0000000000000000000000000000000000000000000000000000000000000000" }
The properties specific to Clique are:
blockperiodseconds- Block time in seconds.epochlength- Number of blocks after which to reset all votes.extraData- Initial signers are specified after the 32 bytes reserved for vanity data.
Extra Data
The extraData field consists of:
- 0x prefix
- 32 bytes (64 hex characters) of vanity data
- Concatenated list of initial signer addresses. 20 bytes (40 hex characters) for each signer. At least one initial signer must be specified.
- 65 bytes (130 hex characters) for proposer signature. In the genesis block there is no initial proproser so the proproser signature is all zeros.
!!! example "One Initial Signer"
extraData field for a Clique network with one initial signer with an address of dd37f65db31c107f773e82a4f85c693058fef7a9
`0x0000000000000000000000000000000000000000000000000000000000000000dd37f65db31c107f773e82a4f85c693058fef7a90000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000`
!!! example "Two Initial Signers"
extraData field for a Clique network with two initial signers with addresses of dd37f65db31c107f773e82a4f85c693058fef7a9 and b9b81ee349c3807e46bc71aa2632203c5b462034.
`0x0000000000000000000000000000000000000000000000000000000000000000dd37f65db31c107f773e82a4f85c693058fef7a9b9b81ee349c3807e46bc71aa2632203c5b4620340000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000`
Connecting to Clique Network
To connect to the Rinkeby testnet, start Pantheon with the --network=rinkeby
command line option. To start a node on a Clique private network, use the
--genesis-file option to specify the custom genesis file.
!!!note
The --genesis-file option is not used when running
Pantheon from the Docker image. Use a bind mount to specify a configuration file with Docker.
Adding and Removing Signers
To propose adding or removing signers using the JSON-RPC methods, enable the HTTP interface
using --rpc-http-enabled or WebSockets interface using
--rpc-ws-enabled.
The Clique API methods are not enabled by default. To enable, specify the --rpc-http-api
or --rpc-ws-api option and include CLIQUE.
The JSON-RPC methods to add or remove signers are:
To propose adding a signer, call clique_propose specifying the address of the proposed signer and true.
!!! example "JSON-RPC clique_propose Request Example"
bash curl -X POST --data '{"jsonrpc":"2.0","method":"clique_propose","params":["0xFE3B557E8Fb62b89F4916B721be55cEb828dBd73", true], "id":1}' <JSON-RPC-endpoint:port>
When the next block is created by the signer, a vote is added to the block for the proposed signer.
When more than half of the existing signers propose adding the signer and their votes have been distributed in blocks, the signer is added and can begin signing blocks.
Use clique_getSigners to return a list of the signers and to confirm that your proposed signer has
been added.
!!! example "JSON-RPC clique_getSigners Request Example"
bash curl -X POST --data '{"jsonrpc":"2.0","method":"clique_getSigners","params":["latest"], "id":1}' <JSON-RPC-endpoint:port>
To discard your proposal after confirming the signer was added, call clique_discard specifying the address of the proposed signer.
!!! example "JSON-RPC clique_discard Request Example"
bash curl -X POST --data '{"jsonrpc":"2.0","method":"clique_discard","params":["0xFE3B557E8Fb62b89F4916B721be55cEb828dBd73"], "id":1}' <JSON-RPC-endpoint:port>
The process for removing a signer is the same as adding a signer except you specify false as the
second parameter of clique_propose.
Epoch Transition
At each epoch transition, all pending votes collected from received blocks are discarded. Existing proposals remain in effect and signers re-add their vote the next time they create a block.
Define the number of blocks between epoch transitions in the genesis file.