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Kakarot Components and Deployment

The entire Kakarot protocol is composed of 2 different kind of Starknet contracts:

  • Kakarot
  • Accounts (EOA & Contract Accounts)

Kakarot

The main Kakarot contract is located at: ./src/kakarot/kakarot.cairo.

This is the core contract which is capable of executing ethereum transactions thanks to its eth_send_transaction, eth_send_raw_unsigned_tx and eth_call entrypoints (defined in ./src/kakarot/eth_rpc.cairo).

Currently, Argent or Braavos accounts contracts don't work with Kakarot.

The mapping between EVM addresses and Starknet addresses of the deployed contracts is stored as follows:

  • each deployed contract has a get_evm_address entrypoint
  • only the Kakarot contract deploys accounts and provides a get_starknet_address(evm_address) entrypoint that returns the corresponding starknet address

For this latter computation to be account agnostic, Kakarot indeed uses a transparent proxy described in Accounts.

Accounts

The Ethereum protocol defines two kind of accounts:

  • Externally Owned Accounts (EOA): accounts managed by a private-key and a wallet
  • Contract Accounts (CA): accounts managed by their stored code (smart contracts)

Each of these account has a given Starknet contract class counterpart in Kakarot.

In the EVM, each account (EOA or CA) is located at an address and has the following properties:

{
  "balance": "0x0ba1a9ce0ba1a9ce",
  "code": "0x6064640fffffffff2060005500",
  "nonce": "0x00",
  "storage": {
    "0x01": "0x02"
  }
}

Currently, Kakarot uses an external regular Starknet ERC20 contract for storing the balances and consequently only the three other fields are stored in the corresponding Starknet contracts. Though it doesn't bring any change from the Kakarot point of view, it would allow Kakarot within Starknet to use Starknet ETH (or STRK) as native token, removing the need for bridging it.

Deploying Kakarot

With the above information in mind the Kakarot EVM can be deployed and configured on Starknet with the following steps:

  1. Declare the account proxy, the contract account and the externally owner account contracts.

    • This generates class hashes which will be used by the core Kakarot contract to deploy accounts.

  2. Deploy Kakarot (core), with the following constructor arguments:

    • Starknet address of the owner/admin account that controls the Kakarot core contract.
    • Address of the ETH token contract (Which is also used as ether within the Kakarot EVM)
    • Contract Account class hash.
    • Externally Owned Account class hash.
    • Account Proxy class hash.

This flow can be seen in the deploy script.