Multi-Chain Account Abstraction Analysis: Exploring the Future of Encryption Infrastructure

Recently, the largest annual Ethereum event in Europe—the Ethereum Community Conference (EthCC 7)—was held in Brussels, Belgium. During the conference, a blockchain developer delivered a speech titled "Revealing the Future: Multi-Chain Account Abstraction Analysis," which delved into the concept of account abstraction (AA), its implementation methods, and its applications across different blockchain networks.

The Core Concept of Account Abstraction

Account abstraction mainly includes two key points: signature abstraction and payment abstraction.

• Signature abstraction allows users to choose any preferred validation mechanism, no longer limited to specific digital signature algorithms.
• Payment abstraction allows users to utilize multiple transaction payment options, such as using ERC-20 assets instead of native assets for payment, or having transactions sponsored by third parties.

This flexibility provides users with a safer and better experience.

ERC-4337 Standard

ERC-4337 aims to address some limitations of externally owned accounts (EOA) in the Ethereum protocol. It introduces more flexible account management and transaction processing methods:

1. userOp structure: The user sends the userOp structure to the Bundler, which collects multiple userOps and sends them to the EntryPoint contract by calling the handleOps function.

2. EntryPoint contract: This contract handles transactions like an operating system, with main functions including:

   • Call the validate function in the account contract to ensure userOp is authorized.
   • Charge fees
   • Call the execute function in the account contract to perform the target operation of userOp.

Native Account Abstraction

In native account abstraction (AA), each account is a contract, and the transaction processing mechanism is directly embedded into the blockchain protocol. Different blockchain networks adopt different AA designs:

• ERC-4337 account abstraction: Ethereum, Arbitrum, Optimism, Base, Linea, Scroll, Polygon PoS
• Native account abstraction following ERC-4337: StarkNet and zkSync Era
• Native account abstraction with privacy design: Aztec

Differences Between ERC-4337 and Native Account Abstraction

1. Operating System Role:

   • ERC-4337 is completed through the collaboration of Bundler and EntryPoint Contract.
   • In native account abstraction, users send userOps to the operator/sorter of the official server.

2. Contract Interface:

   • The entry point function of the verification phase is fixed in both ERC-4337 and native account abstraction.
   • The entry point in the native AA during the execution phase is fixed.

3. Verification Step Limitations:

   • ERC-4337 defines prohibited opcodes and storage access restrictions.
   • zkSync Era has relaxed the use of some OpCodes.

4. Execution step limit:

   • zkSync needs to confirm the existence of the system flag
   • There are no special restrictions during the execution phase for ERC-4337 and StarkNet.

5. Random Number Management:

   • ERC-4337 distinguishes between a 192-bit key value and a 64-bit random value
   • zkSync and StarkNet use a strictly increasing nonce

6. First Transaction Deployment:

   • ERC-4337 includes the initcode field in the userOp structure.
   • StarkNet and zkSync require users to send the first transaction to deploy the account contract.

Differences in ERC-4337 Implementation between L1 and L2

When implementing ERC-4337 on EVM-compatible chains, there are two key differences:

1. Protocol differences: L2 needs to upload data to L1 for security and settlement, and the related costs should be included in the pre-validation Gas.

2. Address differences: The address calculation methods on different chains may vary, leading to the possibility that the account contract address may be inconsistent between Ethereum and L2.

Overall, account abstraction technology is continuously evolving, bringing greater flexibility and user-friendliness to the blockchain ecosystem. With the emergence and refinement of different implementation methods, we can expect to see more innovative applications and improved user experiences.