PoC: Retrofit for EIP-712 Transaction Signing #1114

[containerman17]

Most blockchain applications generate transactions through JavaScript browser-based clients. I expect the same for HyperSDK.

EIP-712 allows structured data to be signed in Core wallet, Metamask, and other mainstream EVM-compatible wallets. We can use it as a temporary solution to sign transactions in HyperSDK.

Drawbacks:

• secp256k1 (Ethereum's curve) is supported by most wallets, but it doesn't enable batch signature verifications, unlike ed25519.
• Requires bringing the whole JSON with data, which is less compact. Addresses and dates would probably need to be represented as strings.
• Not compatible with the current transaction packing and signing logic. This requires the introduction of customizable storage.

Anticipated steps for PoC:

• [x] Check that TokenVM works with secp256k1.
• [x] Test interoperability of EIP-712 signatures between Core/Metamask, Golang, and Node.js.
• [x] Create a rough UI prototype.
• [ ] Implement a non-backwards compatible version of EIP-712 for MorpheusVM or TokenVM.
• [x] Implement a backwards compatible version of EIP-712 for MorpheusVM or TokenVM.

The goal is not to implement but rather to decide if this is implementable and worth implementing.

[containerman17]

Prototype implementation of EIP712 integration in MorpheusVM

• The prototype is available here.
• Integration tests pass; MorpheusVM now uses EIP712.
• Changes to the current auth Auth interface and implementations:
  • Modified Verify(ctx context.Context, msg []byte) error to Verify(ctx context.Context, tx *Transaction) error.
  • Moved Transaction.Digest() call from Transaction to Auth.
• For EIP712 Auth:
  • Reconstructs EIP712 hash and signs it instead of calling Digest.
• Only one Action per Transaction is allowed to keep the prototype simple.
• VM authors can customize the UI by tweaking the MarshalJSON method of an Action, e.g., displaying dates in ISO format and adding decimal separators to numbers.

[containerman17]

This bug https://github.com/MetaMask/metamask-extension/issues/13675 prevents us from using the full uint256 chain IDs. For now, we'll have to use chainId % 4503599627370476 instead of the actual chain ID in EIP712. This issue requires further investigation.

[containerman17]

PR https://github.com/ava-labs/hypersdk/pull/1162 and branch containerman17/delegate-digest-to-auth