RIP-7767: Gas to Ether contract

Abstract

This proposal describes a contract that allows the caller to burn a specific amount of gas, and returns a portion of the gas burned to the caller as Ether.

Motivation

Contract Secured Revenue (CSR) enables contract developers to earn gas fees on their contracts.

It enables new revenue streams in a composable, interoperable, enforceable way. CSR works with any existing token standard and applications. It does not require developers to break or create new contract standards for the sake of capturing value.

However, implicit CSR which is metered by gas spent on every opcode can lead to negative externalities. Developers are incentivized to write bloated contracts, such as using a loop to perform unnecessary storage writes and compute.

This standard proposes making CSR explicit with a special contract, GASBACK, which converts burned gas into Ether with a constant cost. Developers are incentivized to write efficient contracts, so that they can have more gas room to use for GASBACK.

GASBACK offers the following advantages:

• Composability, since Ether is to be paid back immediately to the caller. Also, GASBACK provides a standardized interface for explicit CSR, enabling reusable integration code in tooling and applications.
• Permissionlessness, since contracts integrating GASBACK do not need to be vetted by a centralized team to ensure that they are not intentionally writing bloated code.
• Transparency, since GASBACK can be implemented in Solidity with verified code. This gives developers better clarity and confidence over traditional implicit CSR operated by opaque CRON jobs.
• Maintainability, since GASBACK is simple and flexible.
• Usability, since the gas burned in GASBACK can be easily segmented from regular gas.

Specification

We will refer to this contract as the GASBACK contract.

Behavior

The GASBACK contract takes in calldata bytes32(uint256(gasToBurn)).

The actual amount of gas burned may vary but SHOULD be proportional to gasToBurn.

The GASBACK contract MUST be O(1) in state and compute costs with respect to gasToBurn.

The GASBACK contract SHOULD give the caller a fraction of the gas burned back as Ether (or native currency).

The GASBACK contract SHOULD do a best-effort transfer of Ether to the caller. If transferring Ether with a call fails, the GASBACK contract MAY create a new contract that use the SELFDESTRUCT opcode to force-transfer the Ether.

The GASBACK contract MUST return bytes32(uint256(amountOfEtherGivenBackToCaller)).

The amount of Ether obtained from the burned gas MUST not exceed basefee * actualGasBurned.

The gas burned in GASBACK MAY be excluded from EIP-1559 and block gas limits.

GASBACK can co-exist with traditional implicit CSR, but it is RECOMMENDED for chains to fully migrate to GASBACK if possible for maximum benefits.

Beacon

To support a variety of L2 implementations, there is no designated address for the GASBACK contract.

Chains implementing GASBACK SHOULD include its address in their documentation.

To facilitate onchain discovery, we designate a canonical beacon contract deployed by Nick's CREATE2 factory. This beacon contract returns abi.encode(gasbackAddress) when called.

Final address of the beacon contract TBD.

Implementation of the GASBACK beacon contract is OPTIONAL, as some chains do not support CREATE2 deployments.

Rationale

GASBACK can be implemented as a preinstall, predeploy, precompile.

On the Optimism stack, it is possible to implement GASBACK as a predeploy without modifying the client.

The behavior is deliberately kept simple and flexible so that GASBACK can be implemented in the most suitable way for each EVM chain.

Security Considerations

Implementers must make sure that the precompile does not cause a net increase in the total amount of Ether on the network.

EVM chains hosting any retroactive funding based on gas burned metrics should subtract the total amount of gas burned via the GASBACK precompile.

Copyright

Copyright and related rights waived via CC0.