SDGP-28 Discuss which Provider to use for bridging SDT to other networks

Summary:

The purpose of this proposal is to discuss which provider to use for bridging SDT to other networks, and to start with, to BNB Chain.

Context:

Following the launch of veCAKE on 22/11/2023, Stake DAO joined this new market, on BNB Chain, by introducing a new Liquid Locker for the CAKE token: sdCAKE (Introducing sdCAKE & the Liquid Locker for CAKE | by Stake DAO | Nov, 2023 | Medium).

Therefore, the next step will be to bring the SDT token on the BNB Chain. This would be achieved by bridging the SDT to the BNB Chain.

Rationale:

A number of solutions are available. There are several technologies, and several bridge providers.

Among those presented to us are:

  • LayerZero (https://layerzero.network/)

    • LayerZero is a trustless, omnichain interoperability protocol that enables applications to communicate across different blockchains. It uses a combination of an Oracle and a Relayer to transfer messages between on-chain endpoints. This system ensures secure and efficient cross-chain interactions, allowing users to send messages from one blockchain to another seamlessly.
  • Axelar (https://axelar.network/)

    • Axelar is a secure cross-chain communication platform for Web3, enabling dApps to interact with any asset or application on any chain with a single click. It connects multiple blockchains through a permissionless proof-of-stake transport layer, supporting Turing-complete calls and messages. Axelar’s main feature is its Virtual Machine, which automates complex interchain tasks and supports general message passing, allowing for seamless cross-chain function calls and a more integrated user experience.
  • Celer (https://cbridge.celer.network/)

    • The Celer Network, powering the cBridge, is a layer-2 scaling platform designed to enable fast, easy, and secure off-chain transactions for not only payment transactions but also generalized off-chain smart contract. It employs state channel technology, which allows users to rapidly send and receive transactions off-chain, significantly reducing the load on the main blockchain and enabling more efficient processes. This technology is particularly beneficial for applications requiring high transaction throughput.
  • Wormhole (https://portalbridge.com/)

    • Wormhole, known as Portal, is a bridge technology that facilitates unlimited transfers across different blockchains for tokens and NFTs wrapped by Wormhole. It is designed to enhance interoperability between various blockchains, allowing for seamless asset transfers. This technology is particularly useful for users looking to interact with multiple blockchains, as it simplifies the process of transferring assets like tokens and NFTs across these different networks.

The Stake DAO community and veSDT holders are being consulted on the technology to be used to bridge SDT to BNB Chain.

Arguments to support that selection can be made via the Governance Forum, before the proposal is put to the final vote.

It may also be possible to suggest an alternative solution missing from the listed bridges.

For further information, here is the current ranking of bridges on BSC based on last 30 days’ volume in USD (via https://defillama.com/bridges/BSC):

Means:

  • Human resources: ~0.5 developper day.
  • Treasury resources: Seed initial SDT liquidity with treasury assets.

Proposal specifications:

  • Admin(s): veSDT holders
  • Community feedback: 3 days min
  • Voting duration: 7 days
3 Likes

This proposal is quite essential since we will make a decision which will impact the DAO in the long run, and touches security matters, so please, read carefully, maybe do a bit of research, and provide your opinion!

In my humble opinion, given their volume and history of working together, as well as the fact that they never suffered any hack, Axelar and Layer 0 would be my preferred options.

Axelar opens to the Cosmos ecosystem which might be growing, and could be interesting for us in the future. A DEX like Osmosis for example could be a candidate for Votemarket at some point.
Axelar also has good decentralisation standards, which is good in terms of security. Squid is a great easy UI to interact with and go from any chain to any chain. Finally, they are well integrated with bridge aggregators.

Layer 0 is also an interesting option. The OFT standard would allow SDT to have the same address on all chains, which is convenient for analytics, integration, UI, etc. It also has a good track record in terms of security as it has never been hacked. It is the highest non-native bridge by volume from ethereum, alongside wormhole, and is #1 on BNB Chain.

I am not very technical, so would love to hear other feedbacks, especially from technical people.

5 Likes

Agreed. I can’t say much about the technicals, I’m just a regular user.
But I do like LayerZero a lot, it’s problem free, battle tested and has very low briding fees. So if the chain and coin is supported it’s my go to bridge.

1 Like

I agree on that. However, Stargate has been down for weeks now, and they don’t seem to fix the issue… Kind of problematic imo… I would currently lean toward Axelar as the Squid router UX is really amazing, also with their boost feature where you can bridge in 20 seconds.

2 Likes

Excited to see this discussion going on!

Just wanted to pop in and mention that the OFT is the most battle-tested method for bringing existing tokens cross-chain. Stargate is mandated to support all OFTs, and the Stargate Foundation would love to support StakeDAO and SDT’s expansion to BNB Chain and beyond!

As pointed out by @mevpanda , Stargate is by far and away the largest bridge in the BNB Chain ecosystem (and always has been!). This would also help bring the eyes of other ecosystem participants to StakeDAO.

In reference to the comment above - Stargate has never experienced any downtime, and is certainly working flawlessly at the moment, is there any particular incident that concerns you?

Lamps
Foundation Lead, Stargate Foundation

1 Like

StakeDAO x Axelar - SDT Bridging Proposal

Hi everyone, excited to be here! It’s great to see the community engaging in the discourse, given how crucial this decision is for StakeDAO’s long-term sustainability. I’m representing Axelar Foundation, we recommend that StakeDAO leverages Axelar network’s decentralized infrastructure for SDT bridging.

Situation

StakeDAO is looking for a cross-chain provider for bridging SDT to other networks, starting with BNB chain.

Proposed Solution

Use Axelar network’s new Interchain Token Service (ITS) to make SDT available cross-chain. Interchain Token Service does not require any smart contract work. Even a non-technical person can create a new cross-chain token. The interchain token would be fungible across all EVM chains supported by the Axelar network, and they would have the same token address for improved user experience. Interchain Tokens can be listed on Squid (https://app.squidrouter.com/), which has been integrated into the majority of leading DEXes and wallets such as Pancakeswap, Kyberswap, Quickswap, and many more, thus giving interchain SDT wide distribution. Interchain Token works via mint/burn or lock/unlock and is fully customizable to fit your governance needs. Interchain Token uses Axelar’s decentralized validator set to secure cross-chain transfers.

ITS Portal: https://beta.interchain.axelar.dev/

ITS Docs: What are Interchain Tokens? | Axelar Documentation

Security

Security of cross-chain systems has requirements similar to those of blockchain consensus protocols, namely safety and liveness.

  • Safety: It must be extremely hard for an attacker to steal funds.
  • Liveness: Transactions will always go through within some timeframe.
  • Decentralization: This is not necessarily a separate requirement but rather a means towards satisfying the properties of safety and liveness.

Axelar network security is powered by a combination of:

  • Proof-of-stake decentralized design at the core.
  • Novel quadratic voting mechanism increases the decentralization of the network.
  • Validator security policies, such as mandatory key rotations.
  • Network functions that enable mitigation of malicious interconnected chains [suspend traffic from them].
  • Contract limits that specify how much can be transferred over a time period.
  • Docs
  • Rigorous audits & bug bounties.
  • Code

Uniswap Foundation announced in June of 2023 that Axelar network & Wormhole are approved to support the next phase of its development for cross-chain governance. The foundation has used a group of nine experts to analyze six of the leading crypto bridge providers. After a comprehensive review involving code evaluation and direct interaction with the bridge teams, the committee approved Axelar network & Wormhole for Uniswap’s specific use case of protocol governance. Other bridges, including LayerZero, Celer, DeBridge, and Multichain, did not meet the committee’s criteria.

“The analysis of Axelar concluded that it conditionally satisfies the requirements of the Uniswap DAO’s cross-chain governance use case, as outlined in the Assessment Framework. Axelar employs a proof-of-stake mechanism with sound cryptoeconomic guarantees to secure the protocol. Various aspects of the design of the protocol appear to be well-considered. The size of the validator set and the thresholds for ensuring safety and liveness are sufficient. Its technology stack is built to high standards, and the team maintains good development practices, with strong attention to detail and high activity levels for ongoing improvements. A source of concern for the Committee is a 4-of-8 multisig that governs key aspects of the protocol. Axelar has communicated its plans to move away from reliance on this multisig in Q2 2023 and the committee has weighed in on that process. The Committee recommends that the Uniswap DAO adopt Axelar, conditional on a successful transition away from this multisig. Additionally, the Committee recommends ongoing monitoring of updates to identify areas for improvement in the protocol.” Read more here.
Since then, Axelar network has upgraded to fully decentralized governance. Details of the new Axelar Gateway Governance can be found here. Changes to protocol parameters, including upgrades, now require a quorum of validators to take effect. Axelar network uses the same trust assumptions as message passing for protocol governance changes.

Decentralization

Axelar network is a full-stack decentralized transport layer governed by permissionless PoS consensus. Axelar network is the only “open stack” on the market. All of its components can be upgraded and improved by the community. It provides universal composability of programs with any-to-any cross-chain capability. Users access consolidated pools of liquidity. Developers do not need to speak any custom language; they do not need to make any changes to their chains or UIs.

The Axelar network has three critical components across two functional layers.

  • The first is the network itself, composed of validators responsible for maintaining the network and executing transactions. The validators run the cross-chain gateway protocol, a multi-party cryptography overlay on top of a Layer 1 blockchain. They are responsible for performing read-and-write operations to gateway accounts deployed on connected external chains, voting, and attesting to events on those chains.
  • The second are the gateways, effectively smart contracts that connect the Axelar network and its interconnected external chains. Validators monitor gateways for incoming transactions, which the validators READ. They then come to a consensus on the validity of that transaction, and once agreed, they WRITE to the destination chain’s gateway to execute the cross-chain transaction. The funds are sent to a generated address on the source chain and are locked, and a corresponding asset is minted on the destination chain. The validators and gateways compose the core infrastructure layer.
  • Sitting on top of the validators and gateways are the APIs that enable developers to access the tools and infrastructure enabled by those validators and gateways. This is the application-development layer that applications will interact with to go cross-chain. The underlying core infrastructure layer is used to pass customizable, generalized messages across chains. These APIs are how developers can easily lock, unlock, and transfer assets between any two addresses on any two blockchain platforms, execute cross-chain application triggers, and, more generally, handle any cross-chain requests.

Chain Scalability

Presently, Axelar network connects 54 chains, the highest coverage of all available interoperability solutions.

Axelar network’s coverage and scalability of chains is set to grow exponentially with the launch of Axelar Virtual Machine. The Axelar Virtual Machine is a programmable interoperability layer that automates complex multi-chain deployment and management. The Axelar VM helps developers to span the whole of Web3, as if they were building on a single chain. It is powered by Cosmwasm and turns interoperability into a programmable layer.

The Interchain Amplifier enables developers to permissionlessly set up connections to the Axelar network. Developers gain access to Axelar network’s interconnected network of chains and can “amplify” their resources by paying the cost equivalent to developing only one connection. They can establish connections between new ecosystems or existing chains to add new network properties, such as improved security or better delivery and availability.

For example, once Ethereum develops robust light-clients & ZK proofs for its state, a developer can easily integrate them into the Axelar network to replace or enhance an existing connection.

Developers can also leverage independent connectivity paths to enhance security at the application layer. In a blog introducing multi-path routing, it is described how, for lower-value transfers, an application can choose to accept messages authorized by any of the available connections. For higher-value transfers, the application can require messages to travel multiple independent paths, before approval. This architecture, combined with forward-compatible dApp deployments, enables developers to build scalable interchain technologies while adapting to future improvements in the cross-chain networking layer.

User Experience

Most cross-chain user experiences are complex and painful. 1-click user experiences are necessary to onboard billions of users. Unlike alternative solutions on the market, Axelar network is programmable: it’s a blockchain that connects blockchains, providing an innovative contract platform that supports superior UX:

  • Tools like Interchain Token Service allow dApps and tokens to function on multiple chains in the same way as they function on their native chains.
  • Tools like Axelar Gas Service automate burdensome user tasks like converting into multiple gas tokens to execute a cross-chain transaction.

Cross-chain Intents are live on the Axelar network: Squid, a liquidity router, has used intents on Axelar network to execute cross-chain swaps in seconds. Axelar network can easily work with new cross-chain intent executors. Intents create fluidity between off-chain and on-chain worlds by allowing third parties to fulfill users’ desired actions efficiently. Intents improve interop UX by settling actions almost instantly and then safely finalizing them later.

On the Axelar network, intents have been seamlessly operational. They are exceptionally efficient for transactions that tie value to a specific token, enabling swift order fulfillment. They can also be expanded to more generic messages as long as developers can define their intent structures meticulously. If the value of an intent can be quantified, then solvers can price the risk of it failing to finalize. The risk to the solver of executing a solution to a complex set of user intents between many chains could be aggregated into a single fee, allowing them to execute simultaneously but finalize separately. A small fee to the solver is vastly offset by the improvement in usability and efficiency for the user. We like the work that Essential is currently doing with the concept of “Intent Standards."

One notable Axelar ecosystem application, Squid, has successfully employed intents on Axelar network by integrating with the GMP Express interface. The result? Instant cross-chain communication.

Squid is a cross-chain liquidity router built using Axelar GMP. The dApp finds liquidity in DEXs on connected chains so users can initiate swaps with a single click. The user experience (UX) mimics what users expect when transacting between different chains’ tokens on centralized exchanges – except the entire transaction runs on decentralized infrastructure.

However, there is one aspect in which Squid cannot duplicate a centralized order book using exclusively on-chain infrastructure: as discussed above, finality on connected chains can take 10 to 15 minutes. Instead of making the user wait, risking slippage, Squid employs intents in a fast-finality gadget called Boost. Squid Boost completes the action described hypothetically above in real transactions. It serves a user’s intent to swap X for Y between chains A and B. Boost completes the intent on B, then recoups funds when the transaction finalizes, absorbing bridge risk and delay. Here’s an example transaction.

Conclusion

Given Axelar’s unique design and the ability to meet StakeDAO’s requirements on Security, Decentralization, Chain Scalability, and User Experience, we believe Axelar presents the ideal solution for bridging SDT to BNB and additional chains.

1 Like

Very good inputs from Stargate and Axelar above. I cannot add on the technical pros & cons. But the Axelar solution looks good to me. As additional benefit Axelar opens Cosmos eco-system to Stake DAO, such as Osmosis as outlined above.

2 Likes

Hey guys,
We also evaluated CCIP by Chainlink, and I think it makes sense to add it here to our original suggestions. It also looks like a very solid solution.
Some documentation on CCIP: Chainlink CCIP | Chainlink Documentation
Cross-Chain Interoperability Protocol (CCIP) | Chainlink

1 Like

Ok, looks like we have what we need here.
I will push to vote the following options:

  • Axelar
  • Layer 0
  • CCIP
  • Celer

I think the best is to use ranking voting since there are several possibility so will try to do that.

Adopting the Omnichain Fungible Token (OFT) Standard for StakeDAO’s SDT

Hey everyone, will add thoughts on LayerZero here before the vote takes place. This comment/proposal advocates for the adoption of the Omnichain Fungible Token (OFT) Standard, powered by LayerZero, for StakeDAO’s native token, SDT. This integration enables SDT to seamlessly transfer between networks, beginning with BNB Chain.

LayerZero V2 Update

As noted by the StakeDAO team, LayerZero is a trustless, omnichain interoperability protocol that enables applications to communicate across different blockchains.

Since this discussion was opened, LayerZero V2 was announced. In brief, V2 separates message verification and execution into two distinct phases, providing developers with complete control over their application’s security configuration and how transactions are executed. Verification in V2 shifts away from the Oracle and Relayer model, adopting a modular approach through application-owned Security Stacks. Each application building on LayerZero may select a combination of Decentralized Verification Networks (DVNs) to attest to the validity of a cross-chain message before it is executed on the destination chain. As for execution, in V1 this was accomplished by the Relayer. In V2, that role is moved to the permissionless role of Executor. Additionally, V2 introduces improved handling, message throughput, programmability, and other contract-specific improvements.

Overall, the changes from V1 to V2 only improve the case for SDT to adopt the OFT Standard, as security is now more flexible, the protocol is more extensible, and any type of verification method can be used as a DVN.

OFT Standard Overview

Adopting LayerZero’s OFT Standard enables SDT to fluidly transfer across networks, starting with the BNB Chain. The mint-and-burn model maintains the token’s total supply and value integrity during cross-chain transfers. Its non-custodial nature ensures that SDT remains under StakeDAO’s control, eliminating counterparty risks that are prevalent in other cross-chain solutions. By using the OFT Adapter contract on mainnet, SDT balances across chains will adjust seamlessly, preserving operational continuity and efficiency.

Overall, adopting the OFT Standard for SDT leads to the following benefits:

  • DAO Control: Full ownership of SDT contracts remains with StakeDAO.
  • Broad Network Reach: Access to over 50 chains supported by LayerZero.
  • Supply Consistency: Unified SDT supply across all networks.
  • Fee Structure: Zero additional fees for OFT transfers, with an option for StakeDAO to implement a fee on its own.
  • User Reach: Integration into the Stargate UI introduces SDT to over 200k daily users.
  • Unified Semantics: OFTs are universal, meaning that SDT may extend to new networks that LayerZero supports without any contract upgrades.
  • Battle-tested: OFT standard has been adopted by more 75+ DeFi protocols. Notable integrations include $CAKE, $MIM, $agEUR, $JOE, $BTC.b, and $STG.

Technical documentation can be found here.

OFT Security Overview

From a verification perspective, the OFT Standard grants StakeDAO quite a bit of flexibility, without compromising on security.

  • Security Stacks: The LayerZero protocol offers a modular security framework for applications to configure depending on their specific use case. StakeDAO, by adopting OFT, can select its preferred Security Stack requiring signatures from a unique combination of DVNs that align with its security and trust models. For more information on Security Stacks, please refer to documentation.
  • Diverse Selection of Verification Methods: DVNs for LayerZero V2 currently include Google Cloud, Polyhedra, Gitcoin, Nethermind, Delegate, Abracadabra, Tapioca, Animoca, Blockdaemon, P2P, Obol, StableLab, Switchboard, Portal, Axelar, and CCIP. This diverse group of verification methods allows StakeDAO to take a future-proofed security posture, essential for maintaining the integrity and reliability of cross-chain SDT transactions in perpetuity.
  • Non-Custodial: LayerZero is intentionally designed to be an immutable protocol that has no ability to custody assets or alter the security settings or chain support of integrated contracts. LayerZero is only a router of SDT, nothing more. The protocol cannot take custody of SDT, make security decisions that would alter how SDT transfers are verified, or disable support for a chain that SDT is enabled on.

Conclusion and Next Steps

Adopting the OFT Standard allows SDT to reach BNB Chain with a unified token supply and without fees, while providing StakeDAO with complete ownership and control of SDT contracts, Security Stack preference, and chain support. This integration streamlines the expansion of SDT to new chains, simplifies user experience, and enhances liquidity management, all while ensuring security and autonomy in operations.

We look forward to further discussion of the proposal and appreciate any feedback to this post.

1 Like

Hey @Tube and Stake DAO community, thank you for adding Chainlink Cross-Chain Interoperability Protocol (CCIP) to your original suggestions.

Stake DAO x Chainlink — Cross-Chain SDT Transfers With Chainlink CCIP

Given the historical amount of value exploited by insecure cross-chain bridge protocols ($2.8B+), with the most recent happening only a few weeks ago, Stake DAO requires the most secure cross-chain interoperability protocol. We believe that Chainlink CCIP is the optimal solution to support Stake DAO’s cross-chain expansion due to its unique security properties.

While this proposal is focused on making Stake DAO’s native SDT token available on BNB Chain, we also this see as an opportunity to expand our ecosystems’ long-standing collaboration and establish the groundwork for future cross-chain explorations such as automated cross-chain governance or other forms of cross-chain coordination for the Stake DAO ecosystem in future proposals.

Chainlink Background

Chainlink is a blockchain-agnostic, decentralized computing platform that provides secure access to external data, offchain computation, and cross-chain interoperability. Historically, Chainlink has supported the growth and improvement of Stake DAO since the deployment of Chainlink Automation for Stake DAO Strategies in 2022, which helped the protocol automate fee distribution, deploy strategies, and automatically compound rewards. Stake DAO is already using Chainlink Automation to efficiently decentralize vault management on Polygon, and now, Chainlink CCIP offers a path for further growth without adding additional trust assumptions from new infrastructure.

Chainlink CCIP & DeFi

Chainlink CCIP serves as an interoperability standard for transferring both tokens and/or data between any public or private blockchain network. CCIP currently supports Ethereum, Polygon, Avalanche, Arbitrum, Optimism, BNB Chain, and Base, with support for more layer-1 and layer-2 chains planned to be added over time. Over 80 DeFi protocols have integrated or are integrating CCIP for cross-chain token transfers and/or cross-chain messaging. This includes Synthetix’s use of CCIP for cross-chain transfer of sUSD via the Synthetix Teleporter (Burn and Mint), Aave’s use of CCIP for cross-chain governance, and Swell’s upgrade to CCIP for cross-chain transfers of their liquid staking swETH token.

CCIP & Capital Markets

Beyond DeFi, Chainlink Labs has collaborated with some of the world’s largest financial institutions, market infrastructure providers, and enterprises on how CCIP can securely facilitate the cross-chain settlement of tokenized assets across public/private chains. This includes work with Swift (interbank messaging standard for 11,000+ global banks), DTCC (settles $2+ quadrillion in securities volume annually), ANZ ($1T+ assets under management), and Vodafone DAB (IoT-enabled global trade platform).

Security

Developed with security and reliability as the primary focus by some of the industry’s leading academic researchers, CCIP operates at the highest level of cross-chain security. CCIP’s defense-in-depth security and suitability for the Stake DAO ecosystem can be broken down across multiple categories:

Multiple Layers of Decentralization

CCIP is underpinned by Chainlink’s proven decentralized oracle infrastructure, which has enabled over $9.3T in transaction value within DeFi. Rather than operating as a single monolithic network, CCIP is composed of multiple decentralized oracle networks (DONs) per chain lane, each consisting of a unique source chain and destination chain. This approach allows CCIP to be horizontally scalable, as additional DONs are added to CCIP for each additional blockchain network supported, versus funneling all cross-chain traffic through a single network.

The committing DON is a decentralized network of oracle nodes that monitor events on a given source chain, wait for source chain finality, bundle transactions to create a Merkle root, come to consensus on that Merkle root and finally commit that Merkle root to the destination chain. The executing DON is a decentralized network of oracle nodes that submit Merkle proofs on a destination chain, which is then verified onchain by ensuring the transactions were included in a previously committed Merkle root that has been validated by the Risk Management Network.

Risk Management Network

The Risk Management Network is a separate, independent network that continuously monitors and validates the behavior of CCIP, providing an additional layer of security by independently verifying cross-chain operations for anomalous activity. The Risk Management Network utilizes a separate, minimal implementation of the Chainlink node software, creating a form of client diversity for increased robustness while also minimizing external dependencies to prevent supply chain attacks.

More specifically, the Risk Management Network was written in a different programming language (Rust) than the primary CCIP system (Golang), developed by a different internal team, and uses a distinct non-overlapping set of node operators compared to the CCIP DONs. The Risk Management Network is a wholly unique concept in cross-chain interoperability that builds upon established engineering principles (N-version programming) seen in mission-critical systems in industries such as aviation, nuclear, and machine automation.

To increase the security and robustness of CCIP, the Risk Management Network engages in two types of activities:

  • Secondary Approval: The Risk Management Network independently recreates Merkle roots based on transactions from the source chain, which are then published on the destination chain and compared against the Merkle roots published by the Committing DON. Cross-chain transactions can only be executed if the Merkle roots from the two networks match.

  • Anomaly Detection: The Risk Management Network monitors for abnormal behavior from the CCIP network (e.g., committed transactions with no source chain equivalent) as well as the behavior of chains (e.g., deep block reorgs). If suspicious activity is detected, the Risk Management Network can trigger an emergency halt to pause all CCIP lanes and limit any losses.

Configurable Rate Limits

As an additional layer of security for cross-chain token transfers, CCIP implements configurable rate limits, established on a per-token and per-lane basis, which are set up in alignment with the token contract owners like Stake DAO. Furthermore, CCIP token transfers also benefit from the increased security provided by an aggregate rate limit (across token pools) on each lane, so even in a worst-case scenario, it would be impossible for every token’s limit to be maxed out before the aggregate rate limit on a lane is hit.

Audits and Source Code

Security is the number one priority for the Chainlink ecosystem, a value we do not and will not compromise upon. Chainlink Labs has put an immense amount of resources into developing the security model of CCIP, and as such, is the most audited Chainlink solution to date.

Both the onchain and offchain code for CCIP and the Risk Management Network was subjected to 14 independent audits by five leading security firms (Cure53, Dedaub, NCC Cryptography Services, Sigma Prime, and Trail of Bits) in preparation for the initial mainnet launch.

Additionally, two crowdsourced audits of CCIP and the Risk Management Network were conducted on the Code4rena (C4) platform:

All valid findings were remediated and fixes confirmed with the respective auditors. In some cases, findings represented expected behaviors and were reviewed with auditors upon receipt of audit reports.

The source code for CCIP is publicly viewable on GitHub:

Conclusion

We are thrilled at the opportunity to support Stake DAO’s multi-chain expansion. Chainlink CCIP offers best-in-class security for SDT token transfers to BNB Chain and beyond. Given Stake DAO’s extensive usage of Chainlink Automation for multiple protocol functions, we believe our solution would add little to no additional trust assumptions to the Stake DAO protocol. We look forward to hearing from the community as the vote commences.

I would like to suggest EYWA https://eywa.fi bridge as the most Curve ecosystem friendly.
It is protected by the most decentralized EYWA Oracle Network (130 cross-chain validators).
Besides the basic bridge, EYWA offers you to consolidate your liquidity on Curve in any of the blockchains you are interested in and use it simultaneously in all chains, via EYWA+Curve.

It is not written here unfortunatly, but I think the vote closed now 3 or 4 days ago. And the outcome is CCIP. See Stake DAO web site.