Posted on Jun 11, 2024Read on

Commitment Games and Where to Find Them

Blockchains such as Ethereum have complex transaction pipelines and aim to be decentralized among the actors that constitute the network. Both of these factors increase uncertainty about the confirmation or the state of a given transaction because no single actor has a defining view of the network, a key insight that led to the advent of mev-commit as a credible commitment network. In order to increase certainty about an outcome, network users rely on cryptographic commitments from actors that are usually incentivized by a bid. If a user is able to receive commitments from every single actor that constitutes the network, then their desired outcome is practically guaranteed. But how can a user receive commitments from all actors, and why would all actors agree and commit to the same user demand? In order to attain this outcome, the user and the execution service providers of the networks have to enter into a set of cryptographic engagements considering game theoretic probabilities, which we define as Commitment Games. In this article, we dive into the types of commitment games that will be played by mev actors.

The most common commitment game used today is under mev-boost, which was introduced by Flashbots and established PBS when Ethereum transitioned to Proof of Stake with The Merge in 2022. In mev-boost, relays offer bids from block builders that include a block header and solicit a commitment from the proposer for a specific Ethereum slot. Once the commitment is made, actors on the network are made aware that a block with the committed header will be proposed, leveraging this commitment game to reduce uncertainty. This setting works very well because the commitment doesn’t leak additional information about the state of the network such as a particular transaction, until the execution payload of the committed block is proposed to the network. Actors of the network find out about the state transition multilaterally which maintains the decentralized ethos of Ethereum.

This sets a good example about the design considerations for commitment games as the community demands and advances the types of games that can be played. Commitment games can bring important factors that can lead to mev theft, censorship, or centralization vectors if design considerations for how they are played are not fully thought through. We dive into what games are on the mev horizon below, and follow with an outline of the threat vectors for commitment games and the desired properties of a credible platform to play them.

The Games

Synchronous Commitments

Synchronous Commitments are commitments from multiple actors whose operations only go through when all actors involved have committed to the operation. A simple example is a buy transaction on one chain and a sell transaction on the other. A bid that specifies the chains and the block numbers the operation needs to be executed under can be used to receive synchronous commitments from the block builders on one chain and the sequencer of another. A smart contract on a high throughput chain can record these commitments such that the bid is only rewarded if both are present, aligning actor incentives.

A settlement contract verifies that both commitments are present and rewards/slashes providers based on delivery

Synchronous Commitments are particularly powerful for shared sequencer networks, rollup ecosystems, and based rollups to allow mev operations to interoperate with other chains. Note that they are different than atomic execution as they’re incentivized rather than strictly enforced by the corresponding protocols. They extend the design space for transactions to not only operate in the rollups the ecosystem supports but across rollup ecosystems and L1s, enhancing UX and liquidity for opted-in sequencers. Synchronous Commitments enable efficient arbitrage and liquidity across chains, chain abstraction for end users, and chain abstracted flashloans where a loan can be taken on one chain and paid back on the other.

Multi Block mev

Multi block mev is another commitment game that can be played to unlock net-new revenue for network actors. Multi-block mev opportunities can span from repricing a Uniswap pool over multiple blocks as asset prices change on other domains, to liquidations that continue over many blocks, to long/short positions and non-atomic flashloans. Commitment games for multi-block mev can be attained in a similar manner to Synchronous Commitments, but the committing actors will be on the same chain. For Ethereum, this can be the proposers in the lookahead period or all block builders opted into commitment games; if the smart contract receives commitments from these entities for the multi-block mev bid, then the bidder has sufficient guarantees to consider that their transactions will be executed as committed. Rewards from the bid will only be issued to committing actors if they deliver on their commitments. One downside of this type of commitment game is that it may require higher levels of stake for providers because if they fail to deliver and other committed actors don’t, there can be negative effects for the transaction originator. For single sequencer chains, this can be provided seamlessly by receiving a commitment from the sequencer against the multi-block mev bid.

Instant Bridges and Solver-Enabled Experiences

While these are an extension of Synchronous Commitments, they involve a sophisticated actor such as a Solver who abstracts the complexity away from an end user. For example a Solver can quantify the execution risk of a bridge transaction by engaging in commitment games with network actors, and offer the coins on the destination chain to the end user instantly in exchange for a risk premium.

Solver abstracts commitment pricing and complexity from tx sender

These games can be combined with approaches like fast finality gadgets to fully provide UX similar to web2. As users would be willing to pay more for instant transactions across chains and the solver will bid for this service to network actors, committing entities stand to gain additional revenue by engaging in these commitment games. Other Solver-enabled experiences can include gaming-related transactions, end-user experiences including wallet integrations, Oracle-related optimizations, and more commitment games that we’ve yet to imagine.

Preconfirmations & Common Blockspace Demands

As we highlight in our defining post on preconfirmations, there can be many types of commitment games played with preconfs, ranging from inclusion to execution to post-state guarantees. These continue to be highly desired commitment games by the ecosystem, capturing the attention of researchers and the latest ecosystem narrative. They present net-new revenue opportunities for validators seeking additional yield and block builders that offer them new design spaces for applications and a UX paradigm shift for users.

Other blockspace demands include commitment games such as Top of block, Bottom of block, Indexed execution, and Partial blocks, which the ecosystem has become increasingly familiar with. While these seem like exciting new possibilities for commitment games, they’re unlikely to unlock additional revenue for execution service providers as these services already exist in monolithic ways; all block builders already include top-of-block transactions and have capabilities to include large bundles that are indistinguishable from partial blocks. While these common blockspace demands will certainly increase block builder decentralization and add new angles for multiplicity, most of their economic value is already captured in the current status quo.

Preconfs have a material impact on state transitions and have a corresponding transaction payload, and actors who have unilateral visibility into preconfirmation transactions have both an incentive and the power to take advantage of them. Other commitment games present similar challenges, and playing commitments games on platforms that don’t take these difficult problems into account can lead to censoring, centralizing, or malicious mev related outcomes.

In the next section, we list the desired properties of a credible platform where commitment games can be played without disrupting current network dynamics, an environment we can call The Arena.

The Arena

Guardian map from Halo 3, representing great environment design for an FPS game.

  1. Price Discovery: One of the strengths of PBS is that it creates a competitive environment that leads to the best price discovery for blocks. Take this away, and proposers don’t know if the block they received surfaced the best price. The same goes for preconfirmations and other commitment games, and the actors offering them. If a single actor can unilaterally make the decision of committing or not and they don’t have to continuously compete for this right, they will offer less value for network participants to further their own goals. While actors have the option to pick a single delegate for their commitments, this will result in a loss in expected value as it doesn’t employ a price discovery mechanism.

  2. New Actors: Commitment games should not introduce additional actors having the ability to include or order transactions to their benefit, which can include frontrunning, backrunning, or censoring them for their own gain leveraging their advantageous position. This means no new actor participating in facilitating commitment games should have transaction visibility than existing ones, no “send your request to my RPC and trust me I will route it”, no “here’s an off-chain API” where some actors can access the information before others, all of which are well-studied examples of centralization vectors.

  3. Liveness and Censorship Resistance: Commitment games should not increase potential liveness faults or add additional censorship vectors. A user’s ability to engage in commitment games and a provider’s ability to offer them are both negatively affected if the commitment games can be censored by an actor in between, and a single actor can go offline. Games should continue even if one of the actors goes offline, and users should see no change in their experience as a result.

  4. Decentralization: It’s imperative that any off-chain infrastructure where commitment games can be played is decentralized both for the 3 reasons above and to continue protecting the nature of the networks it affects. In the case of Ethereum, credible neutrality and economic security can be jeopardized if centralized solutions are utilized to offer commitment games, and the centralized actor can build ownership of the network through their advantage over others.

Notably, the absence of these desired properties were recently highlighted problems in Nethermind Research’s “Strawmanning Based Preconfirmations” article and they extend to many other commitment games.

Bonus: Permissionless Extensibility

The developers of a Commitment Games platform may make design choices that favor certain games over others, and it’s important they build in the open. While we at Primev are at the forefront in bringing new Commitment Games to engage in due to our background and experience dealing with mev actors, we are humbled by the community who constantly come up with new methods and games. Therefore it’s imperative that commitment games are extensible and any actor can develop their own commitment games using a permissionless platform for any use case they can imagine, and the commitment game platform does not make design choices that favor certain games over others.

While the current technological landscape renders a “perfect” commitment games platform unfeasible for most real-time use cases, we can construct one that does not disrupt existing PBS dynamics and is compatible with the upcoming ePBS spec, with no additional validator sidecars, no mev-boost forks, and no centralizing RPCs or APIs. And that’s what we at Primev have designed and released with mev-commit, built in the open for the community.

Enter The Arena

Commitment Games are an exciting frontier in the maturity of mev platforms and tooling. From Synchronous Commitments to Preconfs, they bring us closer to creating experiences that deem blockchains the best modern platforms for transacting and more, enabling more liquidity at a cheaper cost, greater security, seamlessly interoperable platforms, and powerful end-user experiences. While the full spectrum of games is yet to be discovered, we at Primev work with actors across ecosystems to enable them to operate more efficiently, which increases yield for economic security providers such as validators and cements additional network effects that make blockchains more robust.

Thank you for reading, and stay tuned as we will be following up with many more exciting updates.

Disclaimer and additional info:

Mev-commit was designed and built over the past year to facilitate commitment games (April 2023 Whitepaper). It’s a chain abstracted, fully decentralized p2p network featuring an encrypted mempool. It places no actors in between the user and execution service providers and enables permissionless applications to be deployed on a separate fast games chain with an oracle that will be progressively decentralized and governed by the community. This approach allows for decentralized and verifiable outcomes for commitment games that can be used to coordinate N number of actors on M number of networks with different execution models. Mev-commit has been thoroughly tested on Ethereum’s Holesky testnet for the past 6 months, and is pending audits before mainnet availability. Go hands-on today to play your first commitment game, Preconfirmations:

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