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Genesis File

What is a Genesis File​

A genesis file is a JSON file which defines the initial state of your blockchain. It can be seen as height 0 of your blockchain. The first block, at height 1, will reference the genesis file as its parent.

The state defined in the genesis file contains all the necessary information, like initial token allocation, genesis time, default parameters, and more. Let us break down these information.

Content of Genesis File​

For BNB Beacon Chain, the geneis files for mainnet and testnet can be found here. Some key contents will be explained as follows.

Genesis Time​

The genesis_time is defined at the top of the genesis file. It is a UTC timestamp which specifies when the blockchain is due to start. At this time, genesis validators are supposed to come online and start participating in the consensus process. The blockchain starts when more than 2/3rd of the genesis validators (weighted by voting power) are online.

"genesis_time": "2019-04-18T05:59:26.228734998Z"

Chain Id​

The chain_id is a unique identifier for your chain. It helps differentiate between different chains using the same version of the software.

"chain_id": "Binance-Chain-Tigris",

Consensus Parameters​

Next, the genesis file defines consensus parameters. Consensus parameters regroup all the parameters that are related to the consensus layer, which is Tendermint in the case of BNB Beacon Chain. Let us look at these parameters:

  • block_size

    • max_bytes: Maximum number of bytes per block is 1048576.
    • max_gas: Gas limit per block. As gas is not used to calculate transaction fees at the moment. The limit. is set to -1.

  • evidence

    • max_age: An evidence is a proof that a validator signed two different blocks at the same height (and round). This is an explicitly malicious behaviour that is punished at the state-machine level. The max_age defines the maximum number of blocks after which an evidence is not valid anymore.

  • validator

    • pub_key_types: Currently only ed25519 is accepted for validators.
"consensus_params": {
    "block_size": {
        "max_bytes": "1048576",
        "max_gas": "-1"
    },
    "evidence": {
      "max_age": "100000"
    },
    "validator": {
        "pub_key_types": [
          "ed25519"
        ]
    }
}

Application State​

The application state defines the initial state of the state-machine.

Genesis Accounts​

In the accounts section (under the app_state), initial allocation of tokens is defined. It is possible to add accounts manually by directly editing the genesis file, but it is also possible to edit the balance after genesis file is created.

[
  {
    "name": "Aconcagua",
    "address": "bnb1y888axmhzz6yjj464syfy68mkhzy9phlv8fzac",
    "consensus_addr": ""
  },
  {
    "name": "Aconcagua",
    "address": "bnb1kdx4xkktr35j2mpxncvtsshswj5gq577me7lx4",
    "consensus_addr": "A71E5CD078B8C5C7B1AF88BCE84DD70B0557D93E"
  }
]

You can see the three different address of all 11 validators. Let us break down these addresses:

  • The first address bnb1y888axmhzz6yjj464syfy68mkhzy9phlv8fzac is used to receive rewards after chain launched. At genesis block, according to gentx info, same amount of staking tokens will be allocated to this address.
  • The second address bnb1kdx4xkktr35j2mpxncvtsshswj5gq577me7lx4 is used for governance.
  • The third address A71E5CD078B8C5C7B1AF88BCE84DD70B0557D93E is used as consensus address for signing new blocks

Token​

The tokens module handles tokens, which contains the information of BNB Beacon Chain native token BNB.

"tokens": [
    {
        "name": "BNB Chain Native Token",
        "symbol": "BNB",
        "total_supply": "20000000000000000",
        "owner": "bnb1ultyhpw2p2ktvr68swz56570lgj2rdsadq3ym2",
        "mintable": false
    }
]

Staking​

The staking module handles the bulk of the Proof-of-Stake logic of the state-machine. This section should look like the following:

"stake": {
    "pool": {
        "loose_tokens": "20000000000000000",
        "bonded_tokens": "0"
    },
    "params": {
        "unbonding_time": "604800000000000",
        "max_validators": 21,
        "bond_denom": "BNB"
    },
    "validators": null,
    "bonds": null
}

Let us break down the parameters:

  • pool

    • not_bonded_tokens: Defines the amount of tokens not bonded (i.e. delegated) in genesis. Generally, it equals the total supply of the staking token, it's shifted by 8 digits for representing decimals.
    • bonded_tokens: Amount of bonded tokens in genesis. Generally 0.

  • params

    • unbonding_time: Time in nanosecond it takes for tokens to complete unbonding.
    • max_validators: Maximum number of active validators.
    • bond_denom: Denomination of the staking token.

  • validators: List of last known validators. Generally null in genesis (except if genesis was generated using a previous state).

  • bonds: List of last known delegation. Generally null in genesis (except if genesis was generated using a previous state).

Governance​

The gov module handles all governance-related transactions. The initial state of the gov section looks like the following:

"gov": {
    "starting_proposalID": "1",
    "deposit_params": {
        "min_deposit": [
            {
                "denom": "BNB",
                "amount": "100000000000"
            }
        ],
        "max_deposit_period": "172800000000000"
    },
    "tally_params": {
        "quorum": "50000000",
        "threshold": "50000000",
        "veto": "33400000"
    }
}

Let us break down the parameters:

  • starting_proposal_id: This parameter defines the ID of the first proposal. Each proposal is identified by a unique ID.
  • deposit_params
    • min_deposit: The minimum deposit required for the proposal to enter Voting Period.
    • max_deposit_period: The maximum period (in nanoseconds) after which it is not possible to deposit on the proposal anymore.
  • tally_params
    • quorum: Minimum percentage of bonded staking tokens that needs to vote for the result to be valid.
    • threshold: Minimum percentage of votes that need to be YES for the result to be valid.
    • veto: Maximum percentage NO_WITH_VETO votes for the result to be valid.

Genesis Transactions​

A gentx is a transaction that bonds staking token present in the genesis file under accounts to a validator, essentially creating a validator at genesis. The chain will start as soon as more than 2/3rds of the validators ( weighted by voting power) that are the recipient of a valid gentx come online after genesis_time.

  "gentxs": [
      {
        "type": "auth/StdTx",
        "value": {
          "msg": [
            {
              "type": "cosmos-sdk/MsgCreateValidatorProposal",
              "value": {
                "MsgCreateValidator": {
                  "Description": {
                    "moniker": "Aconcagua",
                    "identity": "",
                    "website": "",
                    "details": ""
                  },
                  "Commission": {
                    "rate": "0",
                    "max_rate": "0",
                    "max_change_rate": "0"
                  },
                  "delegator_address": "bnb1y888axmhzz6yjj464syfy68mkhzy9phlv8fzac",
                  "validator_address": "bva1kdx4xkktr35j2mpxncvtsshswj5gq577m9l0c3",
                  "pubkey": {
                    "type": "tendermint/PubKeyEd25519",
                    "value": "Xj/NowvRnUXEtzaI2jXn2h/OfGhZssHyDtUgLSQUTj4="
                  },
                  "delegation": {
                    "denom": "BNB",
                    "amount": "1000000000000"
                  }
                },
                "proposal_id": "0"
              }
            }
          ],
          "signatures": [
            {
              "pub_key": {
                "type": "tendermint/PubKeySecp256k1",
                "value": "AoeLfC96urAqZtAxg7cCSXh/+tRxGMthLbvXFu/w9nO0"
              },
              "signature": "b0wYwS7fJcpg0TerEoH22T1CqcZMc3NHm0BusK/+LPMPtqHQuOkbIlPUM12r1iXJjKZhPM/ItFveKIo1oFtfUg==",
              "account_number": "0",
              "sequence": "0"
            },
            {
              "pub_key": {
                "type": "tendermint/PubKeySecp256k1",
                "value": "AreZUwAj6OlZI+xHZm66K4Nj5G/eNei768x77fdFz1fc"
              },
              "signature": "GefEmRyOFk5jGpIZnaGNAOubzPn+wedg62mf8m8yV5cWK7+SByBCcCTHQ+7kB+mkMjOR1AIuXC7Xfou5Q/QhgQ==",
              "account_number": "0",
              "sequence": "0"
            }
          ],
          "memo": "",
          "source": "0",
          "data": null
        }
      }
    ]

A gentx is just a signed message that validator signed to agree to be validators. Let us break down the parameters:

  • Signature related info
    • pub_key: pubkey is used for verifying signature
    • signature: the signature from validator
    • account_number: Unique identifier for the account. It is generated the first time a transaction including this account is included in a block. In gentx, they are all 0
    • sequence: This number is used to count the number of transactions sent by this account. It is incremented each time a transaction is included in a block, and used to prevent replay attacks. Initial value is 0.
    • memo, source and data are all customized details regarding this transaction
  • Delegation related info
    • moniker: the name of validator
    • delegator_address: this is the address that is listed in app_state section
    • validator_address: this is the validator pubkey in bech32 encoding with prefix of bva
    • delegation: this is the delegation amount. It's shifted by 8 digits for representing decimals.

How to Generate Geneis File​

You can generate a default genesis file for your own testnet by running the following command:

bnbchaind init --chain-id

The genesis file will be stored in ~/.bnbchaind/config/genesis.json.