TL;DR: Polymer is building Ethereum’s Interoperability Hub, enabling interoperability among all Ethereum rollups through native IBC technology backed by Ethereum security.

Polymer itself is an Ethereum rollup comprised of the following building blocks:

• Settlement: OP Stack provides settlement and chain derivation logic to and from Ethereum
• Execution: Cosmos SDK provides native IBC interoperability for connected rollups
• Data Availability: EigenDA provides scalable data availability
• Proving: OP Stack’s modular fault proof system supplies:
• Interactive Fraud Proofs: Interactive verification games (IVG) played over a MIPS (Cannon) or RISC-V (Asteric) fault proof VM
• ZK Validity Proofs: Rust ZK program by RiscZero

Interoperability - Where Are We Today?

Since Ethereum went live as the first blockchain to support arbitrary application logic in July 2015, its broad community of developers, investors, and enthusiasts has built one of the most robust networks in crypto. Ethereum has served as fertile ground for experimentation across decentralized application types, from decentralized finance to NFTs and more. Moreover, Ethereum has offered the world not only decentralized compute but also a censorship resistant money and deflationary store of value.

While Ethereum is the largest and most used decentralized network, scaling has been a continued barrier to growth. Layer 2s, however, have partially alleviated the scaling issue and have shown progress, especially in how they enable web 2 scale and user experience, but they also come with tradeoffs. Sharding execution across these Layer 2s, while enabling scalability, has come at the expense of creating siloed execution environments that fragment liquidity, confusing end-users and complicating the developer journey.

Secure composability across Layer 2s has emerged as one of the most significant issues plaguing Ethereum since there is no standard native message passing solution across these chains, and these issues will continue to grow as L2s launch and expand. Early interoperability solutions have attempted to solve this problem by building token bridges, but previous bridges have been insecure and subject to enormous hacks (see here, here, and here for just a small sample). All of the existing arbitrary messaging bridges (AMBs) are implemented as smart contracts with diverging implementations causing fragmented composability.

How do we address these concerns?

Polymer: Ethereum’s Interoperability Hub

With experience building interoperability and cross-chain applications on Ethereum since 2020, the Polymer team is excited to announce our latest designs and architecture connecting Ethereum, rollups, and beyond.

Polymer is not a third party bridge but a Layer 2 rollup that exclusively serves as the Interoperability Hub for Ethereum by providing IBC (Inter-blockchain Communication) as a feature to Ethereum and establishing connections to integrated Layer 2s. This domain specific interoperability model improves upon the domain non-specific approach taken by predecessors. Ethereum itself is verifying IBC execution on behalf of its rollups. We foresee domain specific interoperability becoming increasingly popular in the near term.

Polymer allows applications to have both composability between Ethereum rollups and access to IBC’s growing network of applications and feature set including interchain accounts, application callbacks, and more.

Polymer leverages a hybrid approach, incorporating the settlement functionality of the OP stack with the developer experience and native interoperability of the Cosmos SDK. Polymer also utilizes Eigenlayer’s data availability, which expands the data availability throughput of the Ethereum network by 10 mb/s with more optimizations incoming.

Although Layer 2s are recognizing the need for interoperability by building zero knowledge provers and shared sequencing, these efforts are mostly siloed and limited within their own frameworks and only solve parts of the interoperability problem. We believe Ethereum and its rollups lack a unified interoperability standard that can solve each multi-ecosystem stakeholders’ pain points. Polymer establishes IBC as that interoperability standard across the industry.

Building with IBC

IBC is a blockchain interoperability solution that allows arbitrary data transfer between blockchains connecting over 100 chains and enabling $30B+ in transfers. It is currently the industry’s most battle-tested interoperability protocol. No other interoperability protocol has achieved success at the scale of IBC, connecting over 100 chains and has enabled $30B+ in transfers. Most recently, it has securely facilitated >$1.5b in volume per month. IBC was designed with key attributes aligned with the ethos of blockchain at its core:

• Credibly neutral: IBC is open-source software anyone can contribute to and is not the product of any single for-profit company. It is developed as a public good and has no in-protocol rent extraction - chains, apps, and smart contracts can use IBC free of charge.
• No vendor lock-in: IBC makes it easy for application protocols to switch between security models and interop providers. For example, tokens do not need to be transferred back and migrated when switching interop providers. An IBC channel upgrade can switch out the underlying connections to a new set preventing vendor lock-in.
• Modular Security: IBC was designed to ensure the highest standards of default security while allowing developers the flexibility to lower security for less critical use cases.It can be configured to use consensus verifying light clients, multi-sig signers or even the native bridge of a rollup for verification.
• Offering a robust feature set: IBC offers key functionality that builders need but is not widely used in competing solutions. Developers can use IBC to build not only token transfers, but also interchain accounts (i.e., the ability to allow a module or contract on one chain, to control an account on a remote chain), interchain queries, and asynchronous communication between smart contracts on different chains. Imagine using a single private key to control your wallets across all the chains where you have assets and how that would simplify the user experience for the average user.

Building with the OP Stack

Polymer is joining a long list of chains leveraging the OP stack for its settlement infrastructure, including Base, Zora, and others. We decided to use the OP stack as the settlement framework for the Ethereum Interoperability Hub because it offers:

• Flexibility, Scalability, and Performance: Polymer distinguishes itself from other rollups by focusing on serving the interoperability needs of applications on other rollups rather than executing decentralized applications itself. This departure from the function of the vast majority of rollups requires a great deal of flexibility to build. The OP Stack also has higher capacities and throughput compared to Ethereum mainnet, which is necessary to support the interoperable world of rollups we envision.
• Decentralization via a Thriving and Collaborative Ecosystem: The OP stack is building a robust network and combining engineering talent from not only OP Labs but also Coinbase and diverse open source contributors to accelerate the decentralized development of the Superchain.
• Ethereum Security and Alignment: Ethereum has the right combination of technical, cultural, and economic ingredients to continue growing the most robust decentralized ecosystem in crypto. Our team at Polymer Labs is committed to pushing Ethereum’s scaling roadmap forward, especially scaling interoperability.

Building with Eigenlayer

EigenDA increases the data bandwidth of the Ethereum network using the same underlying asset for security. Here is a breakdown of why we chose to use EigenDA for data availability:

• Ethereum Security: A domain specific interoperability hub should borrow as much security as possible from the same source as the rollup it connects. For rollups inheriting Ethereum security, the most secure option would be to use Ethereum DA. The next best option is to utilize EigenDA which borrows its security from Ethereum staking and a subset of the validator set.
• Scalability: EigenDA significantly increases the data availability throughput of the Ethereum network. The cost model of EigenDA is also more flexible and enables more affordable data availability services to support high-throughput use cases such as crosschain interoperability.

Bringing It All Together

We carefully chose this approach because we think IBC is the right solution for the Ethereum ecosystem. As the highest value settlement layer in crypto, Ethereum offers the greatest security for cross-chain transactions occurring via Polymer than any alternative solution relying on validator sets or blind trust in centralized off-chain entities. As the number of L2s proliferates on Ethereum, the need for a domain specific interoperability hub like Polymer grows. Polymer also leverages EigenDA to improve the scalability and cost effectiveness of the solution.

Polymer plays a critical role in Ethereum’s scaling story enabling builders to create seamlessly composable applications across Ethereum rollups and other domains with an optimal trust model. The interoperable future we are building is one in which crypto achieves mass adoption - one in which users comfortably store their assets on chain, leverage the best applications regardless of which chain they live on, and navigate crypto without complex UX hurdles.

Merging Ethereum and Cosmos

Ethereum and Cosmos have been value aligned and have established foundational innovation to blockchain technology. Both have made great strides in advancing our industry but have done so by building in siloes. Polymer changes this by establishing a path for advancements made in Cosmos to be directly deployed into the Ethereum ecosystem, including bringing IBC to Ethereum.

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