Detailed explanation of the latest proposal of Ethereum EIP-5988: a new solution for L2 interoperability
As the Shanghai upgrade of Ethereum is approaching, various proposals related to it have also emerged, hoping to catch up with the Shanghai upgrade and deploy it together. EIP-5988 has also been submitted to the official Eips.ethereum webpage recently. The main purpose of EIP-5988 is to perform pre-compilation operations for various ZKs to communicate with the main network, so as to save the compilation time and on-chain space required for communication.
EIP-5988 is mainly to solve various communication problems between L2 and L1. With this proposal, ZK-based L2 can be compatible with the security of the main network without reducing its own proof efficiency. OP-based L2 can further enhance the use of the main network. Settlement efficiency.
In addition, EIP-5988 uses the Poseidon hash algorithm this time, which will be used as a unified pre-compiled generation proof method for various L2s. This is also the first new algorithm that may be compatible with Ethereum. Previously, it was mainly tried in various L2s. It is used, but the security has not been tested by mainstream applications for a long time, which is also the main point of controversy caused by EIP-5988.
Get through the communication between L2
In the description of EIP-5988, the most important thing is to propose a new communication method between Layer 2, which packs various Rollup expansion algorithms into a consistent compilation layer, which can be called by the Ethereum main network. Layer 2-like communication.
Intuitive understanding, that is, under the STARK/SNARK and other schemes, a pre-compilation measure is first carried out. Once the proposal takes effect, it will be constructed as a format conversion place after the ZK proof is generated. The Ethereum mainnet does not need to consider the specific source of the message, but only needs to judge whether it conforms to the compiled format, so as to accept or reject it.
Between the current L2 and the Ethereum mainnet, there are extensive compatibility issues. Taking the ZK system as an example, there are currently two main obstacles:
The ZK system has different technical paths, zk-SNARK and zk-STARK are two of the more mainstream ones, and the interoperability between different instances lacks a unified standard;
L2 will choose a self-developed language, such as StarkWare's Cairo, which is different from the solidity used by Ethereum, and needs to be compiled with each other to communicate.
After the implementation of the unified pre-compilation layer, the message format accepted by Ethereum will be unified, and any incoming L2 data type needs to be converted in advance, so as to save the transmission-waiting-response time between L2 and the main network.
Currently, before the unified precompiled layer takes effect, there are three ways of communication between L2s:
CEX/DEX: First transfer tokens to exchanges that are compatible with more than two L2s. However, only asset conversion can be performed, and message transmission cannot be performed directly;
Universal cross-chain bridge: Overlay the L2 network on top of the traditional L1 cross-chain bridge. Asset conversion is possible, and some messages can be delivered with the help of the main network;
L2 cross-chain bridge: Represented by Orbiter Finance, it mainly performs cross-chain between various Rollups, which can be regarded as a cross-chain bridge model in a specific field.
The unified precompilation of EIP-5988 directly standardizes various L2 data formats, rather than directly providing a cross-L2 asset interoperability model. It is still an upgrade and expansion of the Ethereum mainnet and will not damage the Ethereum The security of Fangzhu.com.
With the help of the compatibility from the Ethereum mainnet, it will greatly improve the interoperability of various L2, and it is more in line with the future modular upgrade method of Ethereum.
Poseidon Poseidon powers to be tested
But in addition to the advantages, it is still necessary to pay attention to the problem of unified precompilation, which mainly focuses on the "Poseidon" (Poseidon) hash algorithm it uses, which is also the focus of current community discussions.
Essentially, the workflow of EIP-5988 is to introduce a new precompiled contract that implements the functions used in the Poseidon cryptographic hash algorithm, which can achieve interoperability between EVM and ZK / Validity rollups, and introduce More flexible cryptographic hash primitives.
The main function of the hash algorithm is to convert all kinds of incoming numerical and non-numeric (text, picture, etc.) data into codes with consistent specifications, which is convenient for computer identification and calling. The Merkle tree proof, which is essentially a hashed expression variant of the binary tree, is widely used in various node communications, such as wallets and exchange asset proofs.
The Poseidon algorithm is not a new solution, at least Vitalik has introduced its main function before, and it has good compatibility with various ZK algorithms, which is the main reason why this update is titled Poseidon.
The Poseidon hash function was officially launched in 2019, and it is the same as the popular"Tradition"Compared to other hash functions such as SHA 256 and Keccak, they have not been rigorously tested for validity and security. In the Ethereum network and other blockchain networks, some L2 or other applications have been used. So far, there have been no serious errors in the Poseidon algorithm.
Blockchain cases that have been or plan to use the Poseidon algorithm:
StarkWare plans to use Poseidon as the main hash function for StarkNet and promises to add built-in Poseidon function functionality to the Cairo language.
Filecoin uses Poseidon for different Merkle Tree proofs and for two-value commitments.
Dusk Network uses Poseidon to build a Zcash-like privacy protocol for transactions.
Sovrin uses Poseidon for Merkle tree-based revocation transactions.
Loopring uses Poseidon for Private Trading scenarios on Ethereum.
Polygon uses Poseidon in the Hermez ZK-EVM.
epilogue
epilogue
The vertical layering between Ethereum and Layer 2 expansion schemes is a foregone conclusion, but there are still problems with the security and compatibility between layers, so all kinds of L2 are "using the security of the Ethereum main network, and enhancing their own Extensive attempts have been made on the compatibility of the main network, but on the basis of creating L2 ecological prosperity, it also triggered a L2 split crisis in disguise.
This kind of ecological fragmentation is not conducive to the long-term development of Ethereum and EVM. The competition between various L1s is still going on. How to bridge various ecological fragments has also become a necessary initiative for the Ethereum mainnet. From the mainnet It is the latest trend to start to improve and require all kinds of L2 to perform unified format conversion.
Whether or not EIP-5988 ends up in effect, this prosperity and fragmentation will persist for a long time, and more improvement proposals will be needed to patch it up.
