Genesis File

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.
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

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

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"

}