Hi everyone, Multichain here. Multichain is an infrastructure developed for arbitrary cross-chain interactions. We are secured by MPC and ZKP, and we are envisioned to be the ultimate router for Web3.
We sincerely hope that we can help and contribute to the Uniswap community by working together with you.
And here are the answers to the 15 questions from us:
1. List 3 succinct reasons why you believe your bridge/solution would best serve Uniswap governance.
a. The most significant reason for Multichain’s superior security is its foundation in Secure Multi-Party Computation (SMPC), a theory developed and validated by some of the world’s most renowned cryptographers. The key algorithm implemented at the heart of Multichain’s cross-chain bridge and router is the Threshold Signature Scheme (TSS). These nodes are independent entities that can collectively sign transactions. Using a Distributed Key Generation algorithm, each node independently owns part of the private key shards. The complete set of private keys will never appear, let alone the possibility of being revealed. This can avoid single points of failure, and enhance decentralization and security. The underlying MPC structure design, combined with a wealth of experience in building cross-chain bridges and an abundant supply of liquidity, allows us to offer the cheapest cross-chain fees as well.
b. We are proud to have created the largest cross-chain infrastructure ecosystem, with over 3000 bridges built for our partners and support for more than 80 networks, including both well-known EVM chains and non-EVM chains. Our platform has an excellent number of daily active users, especially on BNB chain. We believe that our strong presence in the BNB community will greatly benefit Uniswap users who are looking to expand their network reach.
c. Innovation is at the core of Multichain’s mission, and we are proud to be the pioneers in cross-chain technology. We were the first to establish a bridge in the crypto space, and we continue to innovate with the launch of RouterV3, which enables native asset bridging. We also led the way in NFT bridging and developed the cross-chain message protocol, anyCall. Most recently, we launched zkRouter, which offers users the option to utilize ZK technology, in addition to our MPC option. Our commitment to innovation and exploration means that the Uniswap community can expect even more exciting developments from Multichain in the future.
2. How long has the system been running on mainnet?
Multichain was born on July 20th, 2020, under the name Anyswap. We have been running on the mainnet for 2 years, 6 months. Our focus has always been on addressing the need for distinct and diverse blockchains to communicate with each other seamlessly.
From the outset, our main product has been the asset cross-chain bridge, which has undergone several iterations and was later upgraded to become the core cross-chain solution, Router. We also developed an NFT cross-chain solution, which further expanded the capabilities of our platform.
At Multichain, we are committed to building and improving our cross-chain infrastructure to provide the best possible experience for our users.
In addition to promoting interoperability across different networks and facilitating smooth asset and value transfers, Multichain also enables seamless data and message transmission across chains. In April 2022, Multichain launched anyCall, a general cross-chain messaging protocol that allows for arbitrary cross-chain messaging.
Multichain has been running successfully for almost three years now. Earlier this year, we released the zkRouter whitepaper, which is an important component of Multichain’s inter-chain trust layer public infrastructure. In the near future, applications (such as cross-chain bridges) built on zkRouter will be available to the public.
3. How much value has the system secured? (Current TVL, total transaction volume)
a. Bridge & Router TVL：$1.78 B
b. Total transaction volume: $ 97.73 B
4. Provide a background on your team.
As an exceptional international team, the members of Multichain share a common vision and contribute their unique skills to the project. Established in 2020, Multichain comprises experts from diverse backgrounds in engineering, cryptography, economics, and mathematics. The team is united in their pursuit of becoming the ultimate Web3 router.
The technical members have extensive experience in the blockchain industry and have collaborated for over a decade. Notably, Andre Cronje serves as the architecture advisor of Multichain and is widely recognized as a pioneer in the field of decentralized finance (DeFi). In 2020, Cronje created yearn.finance and Keep3rV1, in addition to contributing to other notable DeFi projects. Moreover, he has played a critical role in shaping Multichain’s technical architecture designs.
Multichain has also garnered numerous contributors from MultiDAO. The DAO is dedicated to achieving the Multichainverse and supporting Multichain in its mission.
5. Please link your developer documentation.
a. https://docs.multichain.org/getting-started/introduction
b. https://multidao.gitbook.io/anycall/the-latest-version/v7/how-to-integrate-anycall-v7
6. Does the bridge support arbitrary message passing?
Yes. We do offer a cross-chain messaging protocol called anyCall, which has been operating reliably for over a year. Our esteemed partners, such as Curve, have leveraged anyCall to enhance their cross-chain LP rewards distribution governance. Under the hood, anyCall is powered by the MPC network, and its security is fortified by MPC cryptography. In addition, we have recently introduced zkRouter testnet, which allows messages to be transmitted in a trustless and decentralized manner. By incorporating ZK technology with advanced cryptography and mathematics, zkRouter has eliminated the dependence on trust in the cross-chain process. Compared to other cross-chain bridges in the space, zkRouter provides a new level of security that’s unparalleled.
7. Has the current deployed bridge code been audited? By a third party? What attack vectors and vulnerabilities were identified, if any? Have the identified vulnerabilities been remedied?
Multichain has completed comprehensive audits on all of our products, and we are pleased to make the audit reports available to the public. Audit reports can be seen here: GitHub - anyswap/Anyswap-Audit. Our audit report repository contains a total of 13 third-party audits, including those conducted by esteemed companies in web3 such as TrailOfBits, CertiK, SlowMist, and BlockSec. The audits identified primarily contract issues, though their severity was generally low. We encourage you to review the aforementioned audit report repository for further details. Any vulnerabilities identified during the audit process have been remedied and reviewed by the auditing companies.
Security is one of the highest priorities at Multichain. Multichain has built long-term partnerships with world-leading third-party code auditing companies to conduct code auditing of every version or important update of codes. Multichain also has dedicated 10% of its revenues to a security insurance fund and has two bug bounty programs — one with Immunefi and the other internal.
Multichain has established an academic alliance with leading international cryptography experts who specialize in threshold signature algorithms and MPC in order to keep up with recent advancements in related technologies and drive technological progress.
8. Is there a bug bounty program?
Yes. We have partnered with Immunefi to establish a bug bounty program of up to $2 million. In addition, we have set up a dedicated security mailbox to receive bug disclosures that do not meet the requirements of the Immunefi plan. Furthermore, we have established security partnerships with other industry partners, such as Binance & Multichain’s War Room, to share information about vulnerabilities and security experiences and to create stronger security measures for the industry.
To date, we have issued bug rewards totalling more than $2 million, which has effectively raised the security level of Multichain products. We have also created a security fund to alleviate users’ concerns about security during cross-chain transactions.
9. List ANY portion of the functional bridge that is upgradeable and explain how the upgrade process works.
We do not have upgradeable portions for security reasons. This is to prevent contracts from being accidentally or maliciously upgraded by attackers, potentially leading to asset loss or abnormal functions. By disabling the upgrade feature, we ensure that the contracts remain secure and stable.
10. Do any contracts have an owner or owner-like entity? If so, what can the owner do?
One of the fundamental design principles of Multichain cross-chain contracts is to minimize single-point risks and reduce the attack surface. Unlike traditional contracts, cross-chain contracts have no owner, which adds an extra layer of security. In fact, all Multichain addresses are generated and managed by the MPC network, eliminating the need for an individual or entity to hold ownership. Furthermore, these MPC addresses do not possess a private key, and as a result, there is no single point of failure or vulnerability.
11. What is the security model of the bridge? Please describe the security model for the current implementation of the bridge. What trust assumptions are you making?
At present, our Bridge, Router, and AnyCall products are based on a distributed MPC network security model. Additionally, our latest development, zkRouter, is based on zero-knowledge proof technology.
A distributed MPC network is a distributed asset control network implemented with cryptography. It aligns with the decentralized philosophy of blockchain, where nodes hold private key shards. When the number of nodes that agree to sign reaches a predefined threshold, multiple nodes collaborate to generate a signature, completing cross-chain asset or message transfers. It is important to note that the process of distributed key generation and signature generation ensures that the private key never appears in its complete form, and the security of the process is guaranteed by cryptographic algorithms. Furthermore, Multichain’s MPC network uses a trusted execution environment (TEE) that offers dedicated security isolation hardware, further enhancing security.
zkRouter, on the other hand, is based on zero-knowledge proof technology. It generates zero-knowledge proofs based on the source chain’s consensus results, which are then passed on to the target chain for verification, thereby completing cross-chain transfers. The rigorous mathematical derivation and secure cryptography in the zero-knowledge proofs ensure that no one or entity can act maliciously, and as long as at least one honest participant is present in the system, cross-chain transfers can occur securely. Even in extreme case where all participants are malicious, the system cannot be compromised.
In summary, a distributed MPC network is based on cryptography, while zkRouter is based on zero-knowledge proof technology, which combines cryptography and mathematics.
12. How can an adversary pass a fraudulent message from Ethereum to the destination chain? Please give specific and concrete examples.
Currently, Multichain’s asset cross-chain bridge and router rely on the SMPC-based MPC Network to process cross-chain messages. The MPC Network is composed of independent nodes that verify the message status of the source chain and participate in the subsequent TSS execution based on their own verification results. TSS is a strong consensus determined by cryptography, which can only be completed when a threshold number of MPC nodes participate at the same time, otherwise, there is no result.
Therefore, in order for an adversary to transmit incorrect messages from Ethereum to the target chain while Ethereum is running normally, he must first control an MPC node to initiate a TSS request and inject the incorrect information into the MPC network, thus forging the incorrect information. The execution of TSS then requires the adversary to simultaneously control more than 2/3 of the nodes in the MPC network to complete the action.
Multichain has recently released a solution based on ZKP technology to solve the problem of trust in cross-chain communication called zkRouter. zkRouter relies on ZKP technology to generate proof of Ethereum’s consensus result, and proof of any result not agreed upon by Ethereum’s consensus cannot be generated and verified. The proof supports independent verification and can be completed by on-chain contracts after being passed to the target chain.
In this case, an adversary cannot achieve his goal of tampering with information by attacking either the proof generator or the transmitter. The only path is to challenge the security strength of Ethereum’s consensus mechanism and write incorrect information into Ethereum’s consensus result by attacking Ethereum.
13. How can an adversary withhold a valid governance message from Ethereum to the destination chain? Please give specific and concrete examples.
Regarding the trust mechanism of MPC, under the normal operation of Ethereum, there are three ways to try to withhold governance information on Ethereum.
The first way is to withhold the message from being transmitted to the MPC network, which will not trigger the execution of subsequent TSS. Since all MPC nodes can act as initiators of TSS requests, the adversary needs to disable the network of all nodes simultaneously, or attack or control all nodes simultaneously and make them refuse service or become paralyzed.
The second way is to block the node’s access to governance messages on Ethereum by disabling the node’s network, attacking or controlling the node. If more than 1/3 of the nodes are blocked, the MPC Network cannot complete the TSS execution normally, thus achieving the adversary’s goal of withholding governance messages on Ethereum.
The third way is to control more than 2/3 of the MPC nodes after TSS generation and prevent them from sending the TSS result to the target chain to withhold governance messages. In future plans, the MPC Network will be upgraded to MPC Blockchain, and anyone can send the TSS result to the target chain, making it impossible to withhold governance messages from Ethereum through the TSS transmission path.
Regarding the trust mechanism of zkRouter, there are also two ways for an adversary to withhold governance messages on Ethereum.
The first way is to block zkRouter from successfully obtaining governance messages on chain, either by disabling the network of all Relayer nodes that obtains messages in zkRouter, or by controlling all Relayer nodes so that they cannot obtain or respond to governance messages. Or by disabling all node services that provide transaction queries on Ethereum, so that Relayer has no way to obtain governance messages.
The second way is to disable Ethereum network and so that governance messages cannot be confirmed by consensus or Ethereum’s consensus result is tampered with.
Attacking the transmission of proof to the target chain in zkRouter is ineffective, as long as the target chain is working normally, anyone can send proof to the target chain.
14. What are the ramifications of fraud to the malicious actor(s)? If it is legal ramification, please share the suite of legal action you can provide. If it is slashing, please point us to the codebase of the slashing behaviour and describe in words how slashing works in your system.
The security of Multichain is upheld by the MPC network, a group of trusted nodes. Additionally, the application project has the flexibility to either run its own MPC node or choose a trusted node to form the TSS threshold. Running an MPC node requires a certain amount of veMULTI to be locked up.
Multichain released the zkRouter. The main purpose of zkRouter is to solve the problem of inter-chain consensus verification. Unlike traditional consensus mechanisms that rely on node agreement, ZKP technology only requires one honest node to relay proofs for secure cross-chain communication. Malicious nodes cannot generate valid proofs, ensuring that the trustless security model can reduce dependence on trusted nodes. Once the conversion to zkRouter has been made, then the question of slashing would not apply.
15. Provide any additional information you would like here.
How Multichain can contribute to the Uniswap community:
a. zkRouter: Following the launch of zkRouter by Multichain, we plan to dedicate to upgrading the MPC bridge to zkRouter bridge specifically for the Uniswap community in the near future.
b. BNB chain: Multichain offers a significant advantage on BNB. Currently, Multichain’s TVL stands at $1.84 billion, with $326.24 million TVL on the BNB chain alone. This figure accounts for 17.73% of Multichain’s overall TVL. Multichain’s total volume on all supported chains is $97.78 billion, with $12.5 billion total volume on the BNB chain. This translates to a 12.78% share of Multichain’s total volume, which is significant given the platform’s overall size. Additionally, Multichain allows for easy integration with the BNB chain and supports connections to 30 other chains. Notably, a number of 900 tokens have been bridged to BNB chain via Multichain.
When compared to other cross-chain bridges currently available in the market, Multichain stands out for its extensive support of public chains and asset types, as well as the vast scale of assets on its chain. In the case of BNB chain, Multichain’s data outperforms other similar protocols by a large margin. Details can be seen in the figure below.
In summary, we are confident that Multichain has the potential to bring significant benefits to the Uniswap community and achieve great success.