ERC-7836: Wallet Call Preparation API

Abstract

This proposal defines complementary JSON-RPC methods to EIP-5792's wallet_sendCalls to enable an Application to sign over a call bundle (instead of the Wallet). Methods defined in this proposal are purposed for the Application to sign over calls and submit them to the Wallet with an accompanying signature. This is in contrast to wallet_sendCalls, where a Wallet itself signs over the call bundle.

Motivation

Applications are increasingly seeking to use session keys and scoped permissions to make transactions on a user's behalf, without the user having to approve and sign each transaction in their wallet's interface. One example is an application that automates a user's decentralised exchange trading. As Smart Contract Accounts (SCAs) contain arbitrary execution interfaces that lead to varying calldata formats, it is not possible for an Application to know how to sign over an action for any arbitrary Account implementation, without maintaining a mapping of Account implementations to their signing logic. Apps need a simple way to request the payload that their session keys should sign, given a call or set of calls they wish to make, and a way to execute the calls once signed.

Specification

In this specification, we define two new JSON-RPC methods: wallet_prepareCalls and wallet_sendPreparedCalls.

wallet_prepareCalls

Instructs a Wallet to prepare a call bundle according to the Account's implementation. It returns a digest of the call bundle to sign over, as well as the parameters required to fulfil a wallet_sendPreparedCalls request (ie. capabilities, chainId, context, and version).

After calling wallet_prepareCalls, consumers are expected to sign over the digest and submit the signature and prepared calls to the Wallet via wallet_sendPreparedCalls.

Request

The request is identical to that of wallet_sendCalls.

Response

The response is intended to be forwarded to wallet_sendPreparedCalls (minus the digest).

Example

wallet_sendPreparedCalls

Instructs a Wallet to execute a prepared call bundle (response of wallet_prepareCalls) with an accompanying signature.

Parameters

The request is identical to the response of wallet_prepareCalls, except that it includes a signature.

Response

The response is identical to that of wallet_sendCalls, except that it is a list.

Example

Rationale

These endpoints extend the interface established by EIP-5792, given the emergent needs of application developers.

Adding new endpoints for this specific use case is simpler than adding additional options to the wallet_sendCalls endpoint.

Surfacing the prepared calls should be relatively simple for wallets, who already need to do preparation internally in order to support wallet_sendCalls, and who then submit signed calls on chain.

Backwards Compatibility

TBD

Security Considerations

Needs discussion.

Copyright

Copyright and related rights waived via CC0.