Skip to main content
Cardano NFT-marketplace

The First NFT-marketplace on Cardano

5 people
in the team
5 month
of work

Designed and developed in collaboration with IOHK, a decentralized application on the Plutus platform. The created DApp is one of the first NFT marketplaces on Cardano.

See the case

Account Abstraction: what is it and why is it necessary to crypto world?

crypto wallets

ERC-4337 is an Ethereum standard that provides account abstraction (AA) in the protocol without any changes at the consensus level.

The standard was proposed by Ethereum co-founder Vitalik Buterin and other developers in 2021. In March 2023, it was deployed on the Ethereum mainnet.

Since we have been encountering tasks that require the use of this technology, we decided to compile fundamental knowledge about it into one article. This article will assist engineers in gaining a comprehensive understanding of what AA is, its purpose, and where to further explore to fully master these skills.

Combining contract and EOA

In Ethereum, there are two types of accounts:

  • EOA (Externally-Owned Account), controlled by someone who has the private key.
  • Contract account, a smart contract deployed on the blockchain.

You can read more about the account system here.

According to the new ERC-4337 standard, these two types of accounts are combined into one. The result is a unified account that can both perform token transactions and create contracts simultaneously. It can be thought of as a higher-level abstraction above the two types of accounts.

Why is ERC-4337 needed?

The answer is simple: to build next-generation wallets that combine the advantages of a smart contract and an EOA account.

Today, most wallets (e.g., Metamask) are typical EOAs based on a private key. This model requires signing every transaction with the private key, making it cumbersome for users to interact with the wallet. Moreover, losing the private key means losing access to the wallet.

On the other hand, there are alternative contract-based wallets (Gnosis wallet). A smart contract allows implementing custom wallet logic, such as multi-signature functionality. However, users of such wallets still need an EOA account to call smart contract functions and pay gas fees.

Important! An EOA account is required because only it can initiate transactions in the blockchain. An EOA account signs transactions with its private key and pays gas for their execution.

ERC-4337 combines the features of EOA-based wallets and contract wallets by using pseudo-transactions instead of regular transactions. This eliminates the need to sign each transaction with a private key. This approach replaces ERC-2771 with meta-transactions. You can read more about it here. Pseudo-transactions provide abstraction over the user's account. 

How does it work?

Alchemy has prepared a series of articles on the topic of account abstraction. These articles not only explain the new standard but also give a step-by-step description on why specific approaches were used in the standard. From a technical perspective, these are the most useful articles I've encountered, aside from Vitalik's articles. I believe that developers should definitely read them to gain a better understanding.

  1. You Could Have Invented Account Abstraction: Part 1
  2. Account Abstraction Part 2: Sponsoring Transactions Using Paymasters
  3. Account Abstraction Part 3: Wallet Creation
  4. Account Abstraction Part 4: Aggregate Signatures

Now, you can go ahead and read the "laws." Welcome, ERC-4337!

Below, I'll show a few general diagrams and briefly explain the operation process of the standard. The main actors are:

  1. Bundler. A specialized service that organizes an alternative mempool for storing pseudo-transactions and adds transactions to the Ethereum Block as if they were regular transactions.
  2. Entry point contract. This is a singleton. Essentially, it's a contract that serves as a trusted entry point for the Bundler. The contract handles the validation and execution of transactions.
  3. Paymaster. A smart contract that can participate in paying gas fees for executing user pseudo-transactions.
  4. Account. Or Wallet. Essentially, it's a smart contract that implements the logic of a user's wallet. The core business logic of working with the wallet in a DApp is described here.

How Bundler works

Here's what happens in the diagram:

  1. Users prepare their pseudo-transactions, correctly called UserOperations in the standard.
  2. They are then sent to the alternative mempool.
  3. The Bundler retrieves UserOperations from the alternative mempool.
  4. The Bundler packages UserOperations into regular transactions.
  5. The Bundler adds these transactions to the Ethereum block.

Simplified ERC-4337 workflow

In the simplest form, users can request the Bundler to execute a transaction on their Wallet contract on their behalf. The Bundler pays the gas fees. Different models can be devised for how the Bundler obtains funds for gas payment. For example, it could do it for free, issue a credit to the user with an expectation of future reimbursement, or directly deduct gas funds from the user's wallet.

Here's what happens in the diagram:

  1. Users send their UserOperations to the alternative mempool, where they are picked up by the Bundler.
  2. The Bundler processes UserOperations, checking each one's validity through the validateOp() call on the Wallet contract. This validation ensures that unnecessary gas isn't spent on invalid transactions.
  3. The Bundler forwards the UserOperations to the trusted EntryPoint contract. This contract validates transactions again and executes calls for each user's wallet.

Slightly more complex ERC-4337 workflow

This diagram resembles the simplified one but introduces a few new contracts: Factory, Paymaster, Aggregator.

Here's what happens in the diagram:

  1. Users send their UserOperations to the alternative mempool, where they are picked up by the Bundler.
  2. The Bundler sends UserOperations to the Aggregator contract for generating a combined signature. In essence, UserOperations are grouped, and the group receives a single signature. This allows executing transactions in batches, reducing costs compared to individual transactions. During aggregation, UserOperations are validated by calling validateOp() on the respective Wallet contracts.
  3. The Bundler forwards the aggregated UserOperations to the trusted EntryPoint contract. This contract validates transactions again and executes calls for each user's wallet.
  4. If the wallet contract has not yet been created, the user's wallet will be created before executing the transaction through the Factory contract.
  5. If a trusted Paymaster contract is specified in the UserOperation, the gas fee for that UserOperation will be deducted from it. Gas fees are only deducted if the Paymaster contract allows it. The EntryPoint contract checks this through the validate() function for each UserOperation.

Use Cases

The ERC-4337 standard opens up new possibilities for user wallets. Below, I'll describe the most common and relevant use cases.

  1. Multisig: Sharing a wallet among a group of users. This was possible for contract-based wallets but not for EOAs.
  2. Social recovery: Allowing users to recover access to their wallet. If one user loses access, other wallet owners can help them recover it, or recovery can be implemented in other convenient ways.
  3. Different signature schemes: The standard allows using other digital signature verification algorithms, such as BLS or quantum-resistant algorithms in the future.
  4. Batching multiple operations: The ability to call multiple operations on the wallet within a single transaction. For example, when swapping tokens on Uniswap, you can call approve() and transferFrom() in a single transaction.
  5. Gas abstraction: Setting the address from which gas payments will be deducted. This means that DApps can pay gas fees for users, or users can pay gas from a second wallet. Other use cases are possible, such as paying gas fees in an ERC-20 token or exchanging one token for another within the wallet contract.

Important! Thanks to the standard, it's possible to implement practically any set of functions for a wallet. You can come up with your own use case.

In the near future, we plan to release an article on how we implemented AI in one of our client projects. Subscribe to stay informed about the release of this article.

Bundler

There are two popular Bundlers:

  1. Go Bundler by Stackup
  2. TypeScript Bundler by Infinitism

Important! At the time of writing this article, node data providers are beginning to offer products to build Account Abstraction. For example, for early access to Alchemy, you can fill out a special form. The product itself is here. Or Biconomy, which uses Account Abstraction to provide a convenient SDK for easy blockchain interaction.

Contracts

Contracts were written for the standard. You can view them here.

The contract EntryPoint.sol.

The contract for a simple wallet SimpleAccount.sol.

The contract for a wallet factory FactorySimpleAccount.sol.

The base contract for implementing a Paymaster.

Important! The contracts were audited by OpenZeppelin. You can read the audit results here.

SDK for Sending UserOperation to the Network

To send UserOperation to the alternative mempool, various SDKs are already available. For example, @account-abstraction/sdk. This SDK is developed by Infinitism and is compatible with their own bundler.

Contribution to this article

Thank you very much for reviewing this material. If you'd like to participate in the development of this and other materials and make edits and changes, please visit our GitHub repository, and contribute your suggestions.

More useful materials

Featured story
myths

Articles

web3
dApps
startup
Myths about Blockchain Product Development

Nico Bordunenko

Project manager at MetaLamp

Featured story
mvp launching rocket

Articles

business
startup
MVP
Who should be hired on the team to launch an MVP?

Alexey Sukharev

HEAD OF Sales DEPARTMENT

squares

Articles

cardano
web3
NFT
The first NFT marketplace on Cardano

Stanislav Zhdanovich

Haskell developer

zksync
Hot
rwa
New
anonymus
New
Zero-knowledge proof explained and 2024 Trends

Yevgeniy Biktimirov

Venture Analyst

Articles

ethereum
web3
dApps
cpay
Featured story
stock market chart
Featured story
planets
fundraising
Featured story
cto
wallet
Account Abstraction: A Tool Against Gas Fees in Your dApp

Nico Bordunenko

Project manager at MetaLamp

Articles

ethereum
web3
tokens
Featured story
rocketcomputer
Featured story
How to create a design for a startup MVP in 7 days

Julia Cherepanova

Head of Design Office

Articles

startup
MVP
design
crypto wallets
Featured story
speed up development
myths
Featured story
Myths about Blockchain Product Development

Nico Bordunenko

Project manager at MetaLamp

Articles

web3
dApps
startup
mvp launching rocket
Featured story
Who should be hired on the team to launch an MVP?

Alexey Sukharev

HEAD OF Sales DEPARTMENT

Articles

business
startup
MVP
galaxy
Featured story
magazine
Top 6 Trends in Crypto Apps 2023

Roman Shtih

CEO Metalamp

Articles

web3
dApps
cryptocoffee
investments
investors
squares
The first NFT marketplace on Cardano

Stanislav Zhdanovich

Haskell developer

Articles

cardano
web3
NFT
stair
bridge
abstraction
How we use our own training program to hire Plutus engineers

Svetlana Dulceva

The Education Program Supervisor

Articles

education
cardano
web3
mountains
computer in space
A perfect HR: why are IT companies happy with our junior developers?

Svetlana Dulceva

The Education Program Supervisor

Articles

education
web2
business
salary
IT developer
cardano
chains
abstraction
salary
Featured story
rocket
a man with books
Featured story