Ethereum’s research on stateless clients is believed to contribute to the long-term health of the network. Despite all the progress made, Vitalik Buterin stresses that they are currently not available in practice due to some fundamental limitations.
At the Unitize conference, the co-founder of Ethereum, Vitalik Buterin, presented the latest images of the latest developments and problems related to the stateless client transition.
In short, a stateless client is a way of allowing nodes to fully participate in validation without having to maintain the early history of the entire blockchain. The status represents all current balances, smart contract code and their respective data.
Each new block only makes small changes to the status, but all changes must be verified against the entire blockchain, which makes it very inefficient. Stateless clients are at the heart of the Ethereum 1.x plan, which aims to keep the existing chain in a usable state. This research is also important for Ethereum 2.0:
“In an Ethereum 2.0 sharding context, stateless clients are basically mandatory because nodes get rapidly reshuffled between different shards.”
Vitalik Buterin also emphasized that stateless clients are also being investigated in other blockchains like Bitcoin. Stateless clients rely on cryptographic technology to only calculate and check status changes without having to save the status itself in memory.
Issue of Proof Creation
The current state-of-the-art-solution relies on the Merkle proofs to check the condition through the concept of a witness that contains information about the changed condition part. However, due to Ethereum’s current inefficiency, this technology has several major disadvantages that can result in a maximum witness size of 405 megabytes per block.
The optimization can reduce the size of the witness server to a maximum of 2 megabytes, which can be reduced by an average of 600 KB. However, this is still much larger than the current Ethereum block size of around 50 KB.
Buterin’s current alternative is Polynomial Commitment, a system of evidence that relies on polynomial functions to represent data. With certain encryption attributes, they may only use a small witness to prove “great value”.
However, he explained that there is a big problem with this method. Merkle has proven that due to its tree structure, it is easy to partially update, but the polynomial promises to completely change the entire curve, making the cost of calculating witnesses very high.
There are many possible solutions to this problem, for example a hybrid model with “Verkle trees” that combines polynomial obligations into a tree structure.
Research Still in Progress
Vitalik Buterin pointed out that every possible solution has its own problems and needs further research. After his speech, he said:
“There are a bunch of fancy arithmetic techniques that allow us to cut these witness sizes down to the point where the extra data that stainless clients need to download is actually not that much. But still, research and still a lot of re nement required, and this is something where we actively welcome more help from the academic research community.”
The presentation showed that stateless clients who rely on breakthroughs in cryptographic research may not soon enter Ethereum. Due to concerns that the blockchain is too heavy for normal devices, Ethereum’s capacity for transactions is currently subject to targeted restrictions.
For normal users, this means that natural gas prices can remain high for the foreseeable future unless demand falls to a lower level – or the secondary solution compensates for this weakness.