Skip to content

Latest commit

 

History

History
93 lines (67 loc) · 3.61 KB

kakarot_components.md

File metadata and controls

93 lines (67 loc) · 3.61 KB
Raw

Kakarot Components and Deployment

The entire Kakarot protocol is composed of 4 different contracts:

  • Kakarot (Core)
  • Contract Accounts
  • Account Registry
  • Blockhash Registry

Kakarot

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

This is the core contract which is capable of executing decoded ethereum transactions thanks to its invoke entrypoint.

Currently, Argent or Braavos accounts contracts don't work with Kakarot. Consequently, the deploy_externally_owned_account entrypoint has been added to let the owner of an Ethereum address get their corresponding starknet contract.

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 compute_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.

Contract Accounts

A Contract Account is a StarkNet contract. However, it also acts as an Ethereum style contract account within the Kakarot EVM. In isolation it is not more than a StarkNet contract that stores some bytecode as well as some key-value pairs which were assigned to it on creation. It is only addressable via its StarkNet address and not an EVM address (which it is associated with inside the Kakarot EVM).

Externally Owned Account

Each Externally Owned Account in the EVM world has its counterpart in Starknet by the mean of a specific account contract deployed by Kakarot.

This contract is a regular account contract in the Starknet sense with __validate__ and __execute__ entrypoint. However, it does decode and validate an EVM signed transaction and redirect it only to Kakarot. Further development will allow the user to have one single Starknet account for both Starknet native and Kakarot deployed dApp. For a general introduction to EVM transactions, see the official doc.

Blockhash Registry

The BLOCKHASH opcode is a particular opcode that requires the EVM to be aware of past blocks (see also). Since this is not feasible from within Starknet, we deployed a block hash registry contract on Starknet to make this data accessible on-chain.

The blockhash registry enables this by holding a block_number -> block_hash mapping that admins can write to and Kakarot core can read from.

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.

  3. Deploy Blockhash Registry

  4. Store the addresses of the blockhash registry contracts in Kakarot core using set_blockhash_registry. This is required for Kakarot to access the last 256 bock hashes.

This flow can be seen in the deploy script.