# Genesis JSON
This page describes the details of `genesis.json` file.
## Genesis JSON File Structure
The `genesis.json` file structure is described in the following table.
| Field Name | Description |
| ---------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| config | The blokchain configuration. See the section [Config](#config). |
| nonce | (deprecated) This field is derived from the Ethereum, but not used in Klaytn. |
| timestamp | The unix time when a block is created. |
| extraData | The data combined field for signer vanity and RLP-encoded istanbul extra data that contains validator list, proposer seal, and commit seals. |
| gasLimit | The maximum gas amount that used in a block. |
| difficulty | (deprecated) This field is derived from the Ethereum, but not used in Klaytn. |
| mixhash | (deprecated) This field is derived from the Ethereum, but not used in Klaytn. |
| coinbase | An address to which miner receives the reward. This field is only used for Clique consensus engine. |
| alloc | The predefined accounts. |
| number | The block number field. |
| gasUsed | The amount of the gas which used for a block. |
| parentHash | The hash value of the previous block. |
### Config
The `config` field stores the information related to the chain.
| Field Name | Description |
| ----------------------- | ---------------------------------------------------------------------------------- |
| chainId | It identifies the current chain and is used for prevention from the replay attack. |
| istanbulCompatibleBlock | A block number to which istanbul change is applied. |
| istanbul, clique | The type of consensus engine. |
| unitPrice | Unit price. |
| deriveShaImpl | Defines a method to generate transaction hash and receipt hash. |
| governance | Governance information of the network. See the section [Governance](#governance) |
### extraData
The field `extraData` is a concatenation of the proposer vanity and the RLP-encoded istanbul extra data:
* The proposer vanity is 32-byte data which contains arbitrary proposer vanity data.
* The rest of the data is RLP-encoded istanbul extra data containing:
* Validators: the list of validators in ascending order.
* Seal: the proposer signature of the header. For `genesis.json`, it is a byte array initialized with 65 `0x0`.
* CommittedSeal: the list of commitment signature seals as consensus proof. For `genesis.json`, it is an empty array.
**Example**
| Field | Type | Value |
| ------------- | ------------------------- | ---------------------------------------------------------------------------------------- |
| Vanity | 32-byte hex string | 0x0000000000000000000000000000000000000000000000000000000000000000 |
| Validators | \[]address | \[0x48009b4e20ec72aadf306577cbe2eaf54b0ebb16,0x089fcc42fd83baeee4831319375413b8bae3aceb] |
| Seal | byte array of 65 elements | \[0x0,...,0x0] |
| CommittedSeal | \[]\[]byte | \[] |
`extraData` with the above data is created by
```
concat('0x',Vanity,RLPEncode({Validators,Seal,CommittedSeal}))
```
where `concat` is a string concatenation function, and `RLPEncode` is a function to convert a given structure to an RLP-encoded string.
With this function, the output `extraData` for this example is 0x0000000000000000000000000000000000000000000000000000000000000000f86fea9448009b4e20ec72aadf306577cbe2eaf54b0ebb1694089fcc42fd83baeee4831319375413b8bae3acebb8410000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000c0.
## Consensus Engine
The available consensus engines for Klaytn network are Clique and Istanbul. Each engine is explained as follows.
### Clique
The `clique` field stores the configuration for Proof-Of-Authority (POA) based sealing.
| Fields | Description |
| ------ | ------------------------------------------------------------------------ |
| period | The minimum time interval between the consecutive blocks (unit: second). |
| epoch | The number of blocks to reset votes and marked as a checkpoint. |
### Istanbul
The `istanbul` field stores the configuration for Istanbul based sealing.
| Fields | Description |
| ------ | ------------------------------------------------------------------------------------- |
| epoch | The number of blocks to reset votes to be a checkpoint. |
| policy | The block proposer selection policy. \[0: Round Robin, 1: Sticky, 2: Weighted Random] |
| sub | Committee size. |
## Governance
The `governance` field stores governance information for a network.
| Fields | Description |
| -------------- | -------------------------------------------------------------------------------------- |
| governanceMode | One of three governance modes. \[`none`, `single`, `ballot`] |
| governingNode | Designated governing node's address. It only works if the governance mode is `single`. |
| reward | It stores the reward configuration. See the section [Reward](#reward). |
### Reward
The `reward` field stores the information about the network's token economy.
| Fields | Description |
| ---------------------- | ---------------------------------------------------------------------------------------------- |
| mintingAmount | Amount of peb minted when a block is generated. Double quotation marks are needed for a value. |
| ratio | Distribution rate for a `CN/KIR/PoC` separated by `/`. The sum of all values has to be 100. |
| useGiniCoeff | Use GINI coefficient or not. |
| deferredTxFee | A way to distribute TX fee for a block. |
| stakingUpdateInterval | Time interval in block height to update staking information. |
| proposerUpdateInterval | Time interval in block height to update proposer information. |
| minimumStake | Minimum amount of peb to join Core Cell Operators. |
## Example
```
{
"config": {
"chainId": 2019,
"istanbulCompatibleBlock": 0,
"istanbul": {
"epoch": 604800,
"policy": 2,
"sub": 13
},
"unitPrice": 25000000000,
"deriveShaImpl": 2,
"governance": {
"governingNode": "0x46b0bd6380005952759f605d02a6365552c776f3",
"governanceMode": "single",
"reward": {
"mintingAmount": 6400000000000000000,
"ratio": "50/40/10",
"useGiniCoeff": true,
"deferredTxFee": true,
"stakingUpdateInterval": 86400,
"proposerUpdateInterval": 3600,
"minimumStake": 5000000
}
}
},
"nonce": "0x0",
"timestamp": "0x5c9af60e",
"extraData": "0x0000000000000000000000000000000000000000000000000000000000000000f89af85494aeae0ab623d4118ac62a2decc386949b5ce67ce29446b0bd6380005952759f605d02a6365552c776f394699b607851c878e29499672f42a769b71f74be8e94e67598eb5831164574c876994d53f63eab4f36d7b8410000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000c0",
"gasLimit": "0xe8d4a50fff",
"difficulty": "0x1",
"mixHash": "0x63746963616c2062797a616e74696e65206661756c7420746f6c6572616e6365",
"coinbase": "0x0000000000000000000000000000000000000000",
"alloc": {
"0000000000000000000000000000000000000400": {
"code": "0x6080604052600436106101505763ffffffff60e00a165627a7a7230582093756fe617053766b158f7c64998c746eb38f0d5431cc50231cc9fb2cd1fd9950029",
"balance": "0x0"
},
"46b0bd6380005952759f605d02a6365552c776f3": {
"balance": "0x446c3b15f9926687d2c40534fdb564000000000000"
},
"699b607851c878e29499672f42a769b71f74be8e": {
"balance": "0x446c3b15f9926687d2c40534fdb564000000000000"
},
"aeae0ab623d4118ac62a2decc386949b5ce67ce2": {
"balance": "0x446c3b15f9926687d2c40534fdb564000000000000"
},
"e67598eb5831164574c876994d53f63eab4f36d7": {
"balance": "0x446c3b15f9926687d2c40534fdb564000000000000"
}
},
"number": "0x0",
"gasUsed": "0x0",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000"
}
```