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EVM smart contracts on Bittensor

Full Ethereum virtual machine (EVM) compatibility is now available on subtensor (the blockchain in Bittensor). This allows users to:

  • Deploy most EVM smart contracts on subtensor without changing the code
  • Interact with deployed smart contracts on the subtensor blockchain
  • Access standard Ethereum JSON-RPC methods from this EVM compatibility layer on Subtensor, Bittensor's substrate blockchain.

Before you proceed​

Before you proceed to use EVM on subtensor, make a note of the following:

  1. EVM smart contract executes on subtensor: The EVM feature allows the subtensor blockchain to execute Ethereum-compatible smart contracts. Note that all operations performed by this new subtensor EVM feature are executed solely on the subtensor blockchain, not on the Ethereum blockchain.
  2. 1 TAO = 1e18 on subtensor EVM: While working with the subtensor EVM, 1 TAO should be written as 1 followed by 18 zeroes, i.e., 1e18. See this code example: https://github.com/opentensor/evm-bittensor/blob/main/examples/withdraw.js#L58.

Available Precompiles​

The following precompiles are available on the Bittensor EVM:

Standard Ethereum Precompiles​

  • ECRecover (0x1) - Recover the address associated with the public key from elliptic curve signature
  • Sha256 (0x2) - SHA-256 hash function
  • Ripemd160 (0x3) - RIPEMD-160 hash function
  • Identity (0x4) - Identity function (returns input data)
  • Modexp (0x5) - Modular exponentiation
  • Sha3FIPS256 (0x400) - SHA3-256 hash function (FIPS variant)
  • ECRecoverPublicKey (0x401) - Recover the public key from an elliptic curve signature

Bittensor-Specific Precompiles​

  • Ed25519Verify - Verify Ed25519 signatures
  • BalanceTransfer - Transfer TAO between accounts
  • StakingPrecompileV2 (0x805) - Main staking operations including:
    • addStake - Add stake to a hotkey
    • removeStake - Remove stake from a hotkey
    • moveStake - Move stake between hotkeys
    • transferStake - Transfer stake between coldkeys
    • getTotalColdkeyStake - Get total stake for a coldkey
    • getTotalHotkeyStake - Get total stake for a hotkey
    • getStake - Get stake between specific hotkey and coldkey
    • addProxy - Add a proxy delegate
    • removeProxy - Remove a proxy delegate
  • SubnetPrecompile - Manage subnet operations
  • MetagraphPrecompile - Interact with the metagraph
  • NeuronPrecompile - Manage neuron operations

Run the below tutorials to learn how to use the EVM feature on the Bittensor blockchain.

Subtensor Networks
RPC endpoints and Chain IDs for Mainnet and Testnets.
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Configure Hardhat for subtensor EVM
Using Hardhat? Configure it to work with subtensor EVM.
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Configure Remix IDE for subtensor EVM
Remix IDE configuration to use with subtensor EVM.
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EVM on Subtensor: Basics
A beginner-friendly introduction to EVM on Bittensor.
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Install Dependencies
Get started by installing dependencies first.
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EVM Testnet with Metamask
Learn how to set up your Metamask wallet with EVM testnet.
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EVM Localnet with Metamask
Set up your Metamask wallet for a localnet with EVM feature.
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EVM Mainnet with Metamask
Learn how to set up your Metamask wallet with EVM mainnet.
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TAO transfer from Metamask to SS58
Learn how to transfer TAO from Metamask to SS58.
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Transfer TAO between two H160 addresses
Learn how to transfer TAO between two Ethereum H160 addresses.
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Stake with a smart contract
Stake to a hotkey using precompiled smart contract.
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Verify ed25519 with a precompile
Verify an ed25519 signature on subtensor EVM.
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Troubleshooting
How to troubleshoot the most common issues.
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