What exactly is “Danksharding” by V God Science?

On Valentine’s Day, February 14th, Beijing time, Vitalik Buterin, the founder of Ethereum, and Dankrad Feist, a researcher from the Ethereum Foundation (EF), held an educational seminar on the scaling solution “Danksharding”. This workshop is a good starting point for how blockchain can scale at scale while adding “decentralization” and “security” attributes.

What exactly is "Danksharding" by V God Science?

Note: Regarding the meaning of “Danksharding” to Ethereum, it is recommended that readers read the article ” An article to understand Ethereum’s “scaling killer” danksharding”.

The following content is from the “Dude, what’s the Danksharding situation‌ ? ” PPT provided by Dankrad Feist. If you want to watch the full workshop video, you can visit the official youtube channel of the Ethereum Foundation‌.

Overview

1. What is old:

(1) Data fragmentation;

(2) Use the data availability promised by KZG;

(3) Use the separation sharding scheme for raw data sharding;

2. What is new:

(1) Proposer-builder (data generator) separation (PBS);

(2) crList;

(3) 2D scheme;

(4) Proposed Architecture

3. Summarize the advantages and disadvantages

what is old

data sharding

Data Availability (DA) for Rollup and other scaling solutions;

The meaning of the data is defined by the application layer;

  1. Ethereum base consensus (full nodes and validators) has no responsibility other than ensuring data availability;
  2. Why isn’t sharding performed? Compared with native execution, the efficiency of the rollup layer 2 network is 100 times higher, and it is difficult to see what needs to be performed for sharding;

Goal: Provide a data availability layer of about 1.3 MB/s and complete sharding capabilities (10 times the current maximum data capacity, 200 times the usual capacity);

Data sharding has been an Ethereum goal since late 2019;

Data Availability Sampling (DA sampling)

Wondering if O(n) data is available with O(1) work;

Idea: Distribute data into n chunks;

Each node downloads k (randomly selected) chunks;

What exactly is "Danksharding" by V God Science?

Erasure coding

What exactly is "Danksharding" by V God Science?

  1. Expand data using  Reed-Solomon coding (polynomial interpolation);
  2. For example, at encoding rate r=0.5, this means that any 50% of the blocks (d0 to e4) are sufficient to reconstruct the entire data;
  3. Sampling is now efficient (e.g. query 30 random blocks, if all are available, more than 50% are unavailable with probability 2^(-30))
  4. However, we need to make sure the encoding is correct;

KZG Commitments

polynomial

What exactly is "Danksharding" by V God Science?

Commitment C(f)

Evaluate y = f(z)

  1. The prover can compute the proof π(f,z)
  2. Using C(f), π(f,z), y and z, the verifier can confirm that f(z) = y

C(f) and π(f,z) are an elliptic curve element (48 bytes each)

KZG promises as data availability root

What exactly is "Danksharding" by V God Science?

Think of a “KZG root” as something similar to a Merkle root;

The difference is that the “KZG root” promises a “polynomial” (all points are guaranteed to be on the same polynomial, which is not guaranteed by the Merkle root);

Split Sharding Proposal

What exactly is "Danksharding" by V God Science?

what is new

Proposer-Builder (Data Producer) Separation (PBS)

Invented to combat the centralization trend caused by MEV;

MEV means that more mature participants can extract more value than normal validators, which means an advantage for large mining pools;

PBS “contains” this complexity/centralization in a separate role, with an honest minority assumption;

  1. Proposer = Validator, an honest majority assumption implies a high degree of decentralization;
  2. Data Builder = separate role, honest few assumptions, meaning decentralization only needs to ensure one honest (non-censorship) data builder;

What exactly is "Danksharding" by V God Science?

Censorship Resistance Scenarios – crList

  1. The danger of PBS: an efficient Builder can permanently (at some economic cost) censor some transactions;
  2. [Note: In today’s bribery model, the cost of reviewing a transaction is the cost of permanently bribing all proposers without including the transaction;]
  3. crLists allow proposers to specify a list of tx that the builder must include, restoring the old balance;

crList (“mixed PBS” design)

What exactly is "Danksharding" by V God Science?

KZG 2d scheme

Why not encode everything in KZG promises?

  1. requires a supernode (“builder”) to build and rebuild in case of failure;
  2. We wish to avoid the validity of this assumption;

Goal: encode m shard blobs in d KZG commitments;

  1. If we were to do this naively, it would require m*k samples, which would be too much data;
  2. Instead, we can use Reed-Solomon encoding again to expand m promises to 2*m promises;

What exactly is "Danksharding" by V God Science?

KZG 2d Schema Properties

All samples can be verified directly against promises (no fraud proofs!);

A constant number of samples ensures probabilistic data availability;

If 75%+1 samples are available:

  1. All data is available;
  2. It can be refactored from a validator that only observes rows and columns;
  3. Nodes are not required to observe all situations;

Combined together is Danksharding

What exactly is "Danksharding" by V God Science?

What exactly is "Danksharding" by V God Science?

What exactly is "Danksharding" by V God Science?

The execution block and the shard block are built together;

  1. We used to need shard committees because each shard blob might not be available individually;
  2. It is now the responsibility of the data producer to make the execution block valid and all shard blobs available;

⇒ validation can be aggregated;

Danksharding Honest Majority Verification

Each validator chooses s = 2 random rows and columns;

Just prove that the allocated row/column is available for the entire epoch epoch;

An unusable block (<75% usable) cannot get more than 2^(-2s) = 1/16 proofs;

What exactly is "Danksharding" by V God Science?

Danksharding Refactoring

Every validator should reconstruct any incomplete rows/columns they encounter;

In doing so, they should transfer the missing samples to the orthogonal line;

Each validator can transfer 4 missing samples between rows/columns (around 55,000 online validators guarantee full reconstruction)

What exactly is "Danksharding" by V God Science?

Danksharding DA Sampling (Malicious Majority Safe)

future upgrades

Each full node checks 75 random samples on the block matrix;

This ensures that the probability of passing an unavailable block is < 2^(-30);

Bandwidth 75*512 B / 16s = 2.5 kb/s;

What exactly is "Danksharding" by V God Science?

Summarize the advantages and disadvantages

advantage

Simple design:

  1. No need for shard committee infrastructure;
  2. No need to track shard blob confirmations;
  3. No additional builder infrastructure (synchronized payments from the execution layer replace this)
  4. Existing execution layer fee market infrastructure can be used;

Tight coupling between execution chains and shards:

  1. Makes rollup design simpler;
  2. Synchronous calls between zkRollup and the execution chain are possible;

Sharding does not require a separate PBS;

Increased resistance to bribery as data is instantly confirmed by 1/32 of the validator set (instead of 1/2048 in the old sharding scheme) and increased to the full validator set within one epoch;

Thanks to the 2d scheme, full nodes (without running validators) will be able to ensure data availability with 75 samples (2.5 kb/s) instead of 30*64=1920 samples (60 kb/s);

new challenge

Added data generator requirements:

  1. Build a KZG proof of 32MB data (requires 100 cores, but is currently working on a CPU implementation)
  2. A 2.5 GBit/s internet connection is required to distribute samples;

More power is given to data generators as they act as execution + data layer service providers;

  1. Need to be mitigated by crList;

Posted by:CoinYuppie,Reprinted with attribution to:https://coinyuppie.com/what-exactly-is-danksharding-by-v-god-science/
Coinyuppie is an open information publishing platform, all information provided is not related to the views and positions of coinyuppie, and does not constitute any investment and financial advice. Users are expected to carefully screen and prevent risks.

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