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Suave/TEE PoCs of MEV Resistant AMMs

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# [The Latest in DeFi Research](https://www.thelatestindefi.org/) Fellowship Project Repo

## What is this?

This is a proof of concept uniswap v3 pool that auctions off the first swap in the pool per block, enabling the pool to capture some of the LVR arbitrage opportunity which it creates. The auction is written in solidity as a smart contract on [SUAVE](https://suave-alpha.flashbots.net/what-is-suave) and takes advantage of Suave's TEE enabled trusted execution and privacy to make the auction secure. The auction is a 2nd price sealed bid auction and is written to be reusable for other contexts.

The goal of this repo are:

1. Show that smart contract applications are able to sequence themselves for their own benefit.
2. Provide proof-of-concept TEE based auction code that is reusable.
3. Start the conversation on why decentralized applications should be able to control their own sequencing. If you find this interesting and want to chat, DM me on [twitter](https://twitter.com/lobstermindset) :).

## System Components

![System Diagram](https://raw.githubusercontent.com/lobstergrindset/tldr-research/main/solidity_code/assets/system_diagram.png)

The auction is built out of three main contract, two on the target EVM chain and one on Suave:
- `AuctionSuapp.sol`: Contract on Suave which collects user bids and non-bid transactions, and runs one auction per target chain's block. Has a stored private key whose address the `AutionGuard` is aware of and priviledges with submitting auction results. Upon auction completion, will send a [bundle](https://docs.flashbots.net/flashbots-auction/advanced/rpc-endpoint#eth_sendbundle) of transactions to the target chain's block builders for inclusion. Builders are trusted to not break the bundles apart, but the smart contracts in this setup also enforce that swaps will fail if the auction's results are not respected. 
- `AuctionGuard.sol`: Contract on the target chain that other contracts can call into in order to gate functions to only pass after the auction's conclusion. The `AuctionSuave` calls into this contract in the bundle's first transaction. Winning bid transactions must successfully call one of the gated functions in order to unlock the auction.
- `AuctionDeposits.sol`: Contract on target chain that bidders must submit deposits to that are at least as big as their bids. The `AuctionGuard` pulls payments from this contract when processing auction results signed by the key in the `AuctionSuave` contract.

The changes to the UniswapV3 pool are minimal (8 lines of code) and are summarized [here](https://github.com/Lilyjjo/tldr-research/tree/main/solidity_code#uniswap-modifications).

See below a diagram of the system from the view of actions between major actors:
```mermaid
sequenceDiagram
    actor Bidders
    actor Swappers
    participant Suave Auction Contract
    participant BlockBuilders
    participant Ethereum Contracts
    Bidders->>Ethereum Contracts: bid deposits
    Note over Suave Auction Contract,Ethereum Contracts : Ethereum Block N
    Swappers->>Suave Auction Contract: swap txns
    Bidders->>Suave Auction Contract: bids for block N+1
    Suave Auction Contract-->Ethereum Contracts: [auction ends]
    Suave Auction Contract->>Suave Auction Contract: Process Auction
    Suave Auction Contract->>BlockBuilders: Bundle for Block N+1
    BlockBuilders->>Ethereum Contracts: Bundle for Block N+1 
    Note over Suave Auction Contract,Ethereum Contracts : Ethereum Block N+1
```

This is what a `AuctionSuapp`'s generated bundle looks like:

![Bundle Diagram](https://raw.githubusercontent.com/lobstergrindset/tldr-research/main/solidity_code/assets/bundle.png)

## Motivation and Prior Works
This repo focuses on AMMs as an example protocol, as both the LPs and traders of AMMs lose money due to not being able to control the sequencing of trades that occur on-chain.

Normal AMMs lose money due to [loss versus rebalancing (LVR)](https://a16zcrypto.com/posts/article/lvr-quantifying-the-cost-of-providing-liquidity-to-automated-market-makers/), which can be conceptualized as the AMM's LPs being forced to take the bad half of a trade. If an entity is willing to pay for the right to be the first to take a trade, then some of the LVR loss can be recaputured as profit. For ethereum L1, block builders are performing and benefitting from this auction already in their block building process as top of block CEX-DEX arbitrague. In this repo, the AMM takes away the right of the block builder to choose who gets to trade first and instead performs the auction itself. In this way, the AMM is able to capture some of the MEV that it generates instead of leaving it on the floor for block builders to consume.

This repo is different from other<sup>[1](https://arxiv.org/html/2403.03367v1),[2](https://ethresear.ch/t/mev-capturing-amm-mcamm/13336),[3](https://arxiv.org/abs/2210.10601)</sup> proposed AMM auction constructs in that it leverages TEEs (trusted execution environments) to manage and run the auction instead of involving the block builder or other new manager identities. Flashbot's block building platform [SUAVE](https://suave-alpha.flashbots.net/what-is-suave) is used as the TEE provider.

## How to run
1. Download this repo and init the submodules:
   ```
   git clone https://github.com/Lilyjjo/tldr-research.git
   git submodule update --init --recursive
   ```

2. Setup the needed environment variables in `/solidity_code/.env` from the template `/solidity_code/.sample_env`.

3. Decide if you want to run locally or on Suave's testnet (testnet is recommended, it's easier than running your own node)
   
   If you want to run locally:
   Download [`suave-geth`](https://github.com/flashbots/suave-geth) and run with: 
   ```
   ./build/bin/geth --suave.dev --syncmode=snap --datadir YOUR_DESIRED_DATADIR_LOCATION --http --http.api eth,net,engine,admin,suavex --http.addr 127.0.0.1 --http.port 8545 --suave.eth.external-whitelist "*"
   ```

4. Setup the L1 contracts
   
   Setting up the L1 contract takes about ~10 minutes to run. It deploys and initializes all of the uniswap code, the L1 auction code, and sets up the swapper and bidders with the needed funds and state to be able to swap the pool's tokens and place bids on the auction contract. All of the bidder/swapper keys in the .env need funds on the target L1 for this to complete. 
   ```
   cd solidity_code
   forge script script/Deployments.s.sol:Deployments --broadcast --legacy -vv --sig "freshL1Contracts(bool,bool)" true true
   ```
5. Put the outputted deployed addresses into `solidity_code/.env`. Those addresses are used for deploying the Suave contracts and by the rust servers.
6. Deploy the Suave Auction contract
   ```
   cd solidity_code
   forge script script/Deployments.s.sol:Deployments --sig "deploySuaveAMMAuction()" --broadcast --legacy -vv
   ```
7. Put the outputted deployed address into `solidity_code/.env`.
8. Initalize the suapp's inital state
   This command is flakey, run until all CCRs are sent. Recommended to re-build everytime you use the CLI for flakey nonce problems.
   ```
   cd rust_interactions
   cargo build
   ./target/debug/auction-cli amm-auction initialize-suapp
   ```
9. Run the block server and watch as `bidder_0` and `swapper_0`'s transactions are eventually included. You can tell successful bundle lands when the used nonce goes up.
   ```
   cd rust_interactions
   cargo build
   ./target/debug/auction-block-listener
   ```

When running an auction through the rust servers, this is what the output looks like on the happy-path:
<p align="center">
<img src="./solidity_code/assets/auction_running.gif" alt="Auction Running" loop=infinite>
</p>

## Future Works

### Anti Sandwiching Rules

Sandwich attacks, just like LVR, can be partially solved by sequencing rules. The paper [Credible Decentralized Exchange Design via Verifiable Sequencing Rules](https://arxiv.org/abs/2209.15569) lays out rules for ordering swaps which prevent the sequencer from performing sandwich attacks. The idea is that given a starting price, swaps will oscillate around that price until only swaps of one type are left:

![Chart](https://raw.githubusercontent.com/lobstergrindset/tldr-research/main/solidity_code/assets/v_chart.png)

The bundles created by the `AuctionSuapp.sol` can be customized to order the swaps in a way that is compliant with the rules:

![Bundle Diagram](https://raw.githubusercontent.com/lobstergrindset/tldr-research/main/solidity_code/assets/v_bundle.png)

Note that in this system, the swappers would also have to deposit into the deposit contract like the bidders. This is because the ordering of the swaps are dependent on each other, if one fails then the other swaps would not be ordered correctly. Suave has transaction simulation APIs written but they do not currently work.

### Astria

The other major future work is migrating the sequencing rules off of Ethereum and onto a different L1 that offers cleaner sequencing and/or bundle inclusion APIs. In this PoC the AMM's operation is dependent on having MEVBoost's winning Builder include the bundle. It would be better if the L1 natively offered ways for the AMM to express how it'd like to be sequenced. I'm working on building out this capability at [Astria](https://www.astria.org/).

# Issues with this PoC
This is a PoC for many reasons, some inherent in the design and some due to Suave being in development.

Issues:
1. Bundles will only land if the L1's sequencing system accept bundles and if the bundle is given to the correct builder. Currently `AuctionSuapp` only sends the bundle to a single builder. Unless the `AuctionSuapp` pays a high gas fee to aid the builder winning the MEVBoost auction, it's unlikely that the single builder will be the winner. This is why if running the code many blocks can go by without landing any bundles.
2. Bids identifiers are being stored in the `AuctionSuapp`'s contract storage instead of in the confidential store. This can cause bid that are placed too close to the auction's end time to fail to have enough time to populate the contract storage via a callback. This should just be rewritten. 
3. The `AuctionSuapp` is built to run on a single TEE/Kettle. This creates a single point of failure, if the Kettle goes offline so does the AMM.
4. The `AuctionSuapp` doesn't have a safe way to grab the current time, which is needed to tell when to end an auction. The grabbed time could be manipulated by the TEE's host machine, making the TEE/Kettle operator a somewhat trusted entity.
5. Suave doesn't run actual TEEs right now -- this means that this POC does not have trusted or private compute.
6. Suave doesn't update CCR state reliably. If you run the code, you will see that the auction stats will not update even though on the L1 blockscanner you can see bundles landing.
7. Suave doesn't gate CCR callbacks currently. This means people can mess up the Auction's state by calling the callbacks with junk data.

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