InstaGas Architecture

Universal

✅ ERC-4337 ✅ EIP-7702 ✅ RIP-7560

InstaGas is an ERC-4337 compliant paymaster that works seamlessly with any Bundler or any Account Abstraction SDK. It supports gas sponsorship through customizable Gas Policies and can also handle gas payments in ERC-20 tokens as a fallback option.

Future-ready, as it is compatible with EIP-7702 - the proposal that extends Externally Owned Accounts (EOA) functionality to include features from smart wallets, such as transaction batching and gas sponsorship. Furthermore, it is also compatible with RIP-7560, the Native Account Abstraction proposal.

Gas Policies

A Gas Policy is a set of customizable rules designed to sponsor gas for targeted actions.

A Gas Policy can be configured as public, allowing it to be used by anyone calling the pm_sponsorUserOperation endpoint, or as private, accessible only through a unique policy ID.

Gas Policies are set up for a defined time period and can include various rule types. These include account-based rules, which set limits per account, access-based rules that whitelist specific accounts, domains, or IP addresses, and transaction-based rules, which customize policies based on the dApp's contract, callable methods, input parameters, and transaction limits.

The steps to set up a Gas Policy are as follows:

1. Sign up on the dashboard
2. Create a new Gas Policy on a specific network
3. Configure the policy rules
4. Fund the policy and activate it

Smart Wallets

User Operations are transactions specific to Smart Wallets. The smart wallet client constructs the User Operation based on calldata provided by the dApp, either through the Ethereum browser provider, a WalletConnect connection, or an internally integrated dApp. The client then sends a request with the User Operation to InstaGas API to determine if a matching gas policy exists. If a policy is found, the Paymaster returns a valid sponsorship signature. If no match is found, the client defaults to offering the end-user ERC-20 token options for paying gas.

Paymaster Verifier

The traditional Paymaster design sponsors gas indiscriminately, allowing anyone with access to the API key or a private sponsorship id on the client side to consume gas with minimal verification. This exposes both the Paymaster provider and its customers, who set up the endpoint, to draining attacks. We consider the use of rules and policies enforced by a Paymaster Verifier a more secure solution. The verifier checks all applicable gas policies against the submitted User Operation, offering protection against malicious actors attempting to exploit policies that were not intended or properly configured for specific use cases. This ensures that gas policies are enforced as intended.

Paymaster Contract

A Paymaster holds both a deposit and a stake within the global ERC-4337 EntryPoint contract. The deposit, used to cover gas fees, is distinct from the stake, which is locked to ensure security. The EntryPoint can withdraw from the Paymaster's deposit if it determines that the Paymaster has sufficient ETH to cover the gas for the operation via the handleOps method. It then calls validatePaymasterUserOp on the Paymaster contract to confirm the Paymaster's willingness to sponsor the operation. If validatePaymasterUserOp returns a 'context', the EntryPoint’s handleOps method subsequently calls postOp on the Paymaster after executing the main operation. The stake serves as protection against malicious Paymasters, ensuring that if a Paymaster behaves maliciously or attempts to launch a denial-of-service (DoS) attack on the system, its stake can be slashed as a penalty.