#EducationalSeries #Blockchain

Today’s topic is data availability and security. It’s a bit like a math class or boring code — something people don’t want to get close to. But there’s no way around it: if you want to seriously and deeply learn blockchain, data availability and security are unavoidable topics. These are two underlying structures that are extremely easy to overlook, yet they can truly determine whether a public chain can operate healthily in the long term.

When we talk about blockchain, most people focus on price, TPS, gas fees, ecosystem applications, and Layer2 hype (after all, Layer2 has been the focal point of the focal point in the last two years)…… But no matter how high TPS is, how low gas is, or how lively the ecosystem looks, you can’t get around the two most fundamental and most critical blockchain cornerstones: data availability and security.

These two terms may sound technical, but they determine:

• Are your assets truly “under your own control”?

• Can your transactions be verified?

• Will Layer2 suddenly go down or “do evil”?

• Is the public chain’s scaling robust?

• Can developers fully trust the underlying architecture?

If we compare blockchain to a city:

• Security = the city’s public safety system

• DA = whether all public records are open and transparent

• Good public safety, but the ledger isn’t public? — you can still fake things.

• The ledger is transparent, but public safety is bad? — the system will be attacked.

• Only when both exist does the chain become truly trustworthy.

Today, we will use a truly relaxed and easy-to-understand way to thoroughly explain DA and security.

Data availability essentially solves the most fundamental problem: can the on-chain state be verified by all participants? You have to know that the core value of blockchain is “transparency + verifiability,” which means any node should be able to:

• download blocks

• obtain all transaction data

• recompute the state

• fully verify the chain

Only then is a blockchain self-verifiable.

Take Layer2 as an example: L2 processes transactions in its own execution environment, and the final state must be submitted back to L1. But what happens if the submitted data is incomplete?

Users cannot verify
The state cannot be reconstructed
Users cannot “force exit”
The operator can forge transactions
The entire system becomes a centralized database

That is to say, without DA, no matter how high your TPS is, you are not a secure blockchain system.

DA = data must be fully published, remain accessible, verifiable, and reconstructable. It is not simply “whether a server can read it,” but rather:

• all nodes can independently verify

• data will not be intentionally withheld

• users do not rely on the operator

• the whole network has the ability to construct the same state

In other words: without DA, there is no real blockchain.

Traditionally, we thought security was only “resisting attacks.” In fact, complete security includes three layers:

It determines whether the chain can withstand malicious nodes:

• PoW: is the hash power sufficiently decentralized?

• PoS: is the total stake sufficiently large?

• are nodes decentralized?

• can it be exploited by a 51% attack?

The more people jointly maintain the ledger → the harder it is to attack.

A chain must make the cost of attack extremely high, with costs far exceeding potential gains, for example:

• attacking Ethereum requires staking millions of ETH

• attacking BTC requires massive ASIC capability

• attacking Celestia requires a large amount of TIA stake

The higher the cost → the more secure the system.

• are smart contracts trustworthy?

• can state be forged?

• can malicious behavior happen at the contract layer?

• is there off-chain black-box execution?

• can the state root be proven?

Execution security is often where vulnerabilities originate.

Here is the underlying logic that truly affects blockchain security: a blockchain without DA = unverifiable = insecure. This is like a tax system needing an open ledger; a blockchain must make transaction state public. If data is not published on-chain, then the assets you hold cannot even be proven to belong to you.

Let’s use an extremely simple but critically important example.

You hold 10 ETH on an L2, and then the L2 goes down. If:

• the data has been uploaded to L1 (has DA) → you can “force exit,” and the assets can be recovered

• the data has not been uploaded → you can never get your assets back, and you can’t even produce proof

DA is like the “original evidence” of your assets. Without evidence → even the court can’t save you.

In the entire blockchain scaling system, “Data Availability, DA” has always been the most easily overlooked, yet the most critical underlying module. Whether it is Rollups, sharded chains, Appchains, or the latest modular blockchain narrative, the strength of DA almost directly determines a chain’s security, economic model, user experience, and ecosystem scalability.

The industry generally divides DA capability into three major levels. Each level corresponds to a different design philosophy, a different security model, and completely different commercialization scenarios. Below, we will expand comprehensively across six dimensions — architecture design, technical principles, security level, ecosystem prospects, typical projects, and applicable scenarios — so you truly understand the strategic position of the DA sector in the future.

Representatives: Ethereum, Bitcoin (in some scenarios), Celestia (on its own chain)

Layer1 DA is the industry-recognized “gold standard,” and you can even say it is the “gold reserve” of the blockchain world. The reason is only one: thousands, ten thousand, or even one hundred thousand nodes across the network jointly store and verify the same on-chain data. This security comes from strong consensus, from an ultra-dense full-node network, from a globally distributed miner/validator network. Any attacker who wants to tamper with data would have to “break through the entire internet.”

① Data will never be lost: global nodes back it up together Ethereum’s data redundancy is exaggerated:

• full nodes store all block data

• light nodes can sample-verify

• archive nodes preserve historical state

This means that as long as there is still one Ethereum node left in the world, your Rollup data will not disappear.

② Economic security is quantifiable and verifiable

Ethereum’s security comes from the economic model of staked ETH. If an attacker wants to manipulate data, there is only one feasible way: control 51% of validator staked capital. The current cost is as high as tens of billions of dollars, and would also be slashed. This is why Layer1 DA is regarded as an unshakable security foundation.

③ Strongest censorship resistance

The network is distributed across 100+ countries globally, with no single point that can be shut down. No country, institution, or team can unilaterally take data offline.

Drawback 1: extremely high cost

Publishing DA (Rollup Data) is very expensive, for example:

• ETH calldata is costly

• block space is limited

• competition for space pushes gas up

This means: the more your Rollup is used, the more expensive it becomes.

Drawback 2: limited throughput

Ethereum needs to process massive contract calls and transactions every day, leaving relatively limited space for DA.

This type of DA represents a major shift in blockchain design philosophy: “separate execution, settlement, and DA, and let each layer do what it is best at.”

Modular DA is born specifically for scaling. It allows Rollups to no longer rely on Ethereum’s expensive DA, but instead have cheaper, faster, and more scalable data publishing space.

① High throughput + massive data bandwidth

Celestia’s chain achieves horizontal scaling through Data Availability Sampling (DAS).

More nodes = higher DA capability. When the node scale increases, Celestia’s DA throughput can also increase multiplicatively. This is the opposite of L1: traditional L1 becomes slower as there are more nodes, while modular DA becomes faster as there are more nodes.

② Extremely low cost (compared with Ethereum DA)

Taking Celestia as an example: the cost of publishing a piece of DA data is 10–100 times lower than Ethereum. Rollups can use Celestia as the DA layer, while continuing to submit state roots to Ethereum to obtain L1 security (Dual Posting mode). This makes it possible that in the future, all Rollups may migrate to modular DA.

③ Strong decentralization

Modular DA networks also have their own complete validation system:

• validator set

• node network

• light-node sampling verification

• multi-region distributed data storage

It is not a multi-node “centralized database,” but a truly decentralized DA blockchain.

• global Rollups are surging

• more and more Appchains

• L2 costs are entering a price war

• ZK Rollups require massive DA space

• high-data-volume businesses such as MEV, AI, and on-chain games are emerging

In the future, there will be thousands upon thousands of chains that all need DA. This is the super opportunity of modular DA.

Off-chain DA is mainly used by chains pursuing extreme TPS, such as:

• some Solana vendorized fork chains

• high-speed Layer3

• enterprise chains

• game chains

• centralized sidechains

Their core idea is: if data is not put on-chain and only exists on servers, then throughput can be infinitely high.

The composition of off-chain DA usually includes:

• centralized servers

• RPC service providers

• independent data warehouses (such as Data Lake)

• enterprise-grade cloud storage

• no “public validator” system

Off-chain DA is more like Web2, not blockchain.

Because data is in the hands of the operator, if they intentionally hide a block, then:

• users cannot verify

• the state root cannot be reconstructed

• Rollup updates fail

• the chain suffers irreversible damage

• off-chain DA lacks an independent verification mechanism

If a Rollup uses off-chain DA, it means:

• if the operator runs away

• if data is lost

• if servers shut down

• users cannot “force exit” back to the main chain

This risk is extremely fatal.

Off-chain DA is indeed high-performance and low-cost, but the price paid is:

• throughput is great

• decentralization is extremely poor

• censorship resistance is almost none

• if something goes wrong, it is impossible to recover

This is more like a “pseudo-blockchain.”

In the next 5 years, Rollups, AI blockchains, ZK computing, GameFi, and real-time order book systems will all consume massive amounts of DA.

Competition in the DA sector will be:

• who is cheaper?

• who is faster?

• who is more secure?

• who can carry a million-level Rollup ecosystem?

What can be determined is:

• Layer1 DA = value reserve layer

• Modular DA = main battlefield of scaling

Off-chain DA = suitable for centralized high-performance scenarios, but not the Web3 mainstream

#EducationalSeries #Blockchain

Today’s topic is data availability and security. It’s a bit like a math class or boring code — something people don’t want to get close to. But there’s no way around it: if you want to seriously and deeply learn blockchain, data availability and security are unavoidable topics. These are two underlying structures that are extremely easy to overlook, yet they can truly determine whether a public chain can operate healthily in the long term.

When we talk about blockchain, most people focus on price, TPS, gas fees, ecosystem applications, and Layer2 hype (after all, Layer2 has been the focal point of the focal point in the last two years)…… But no matter how high TPS is, how low gas is, or how lively the ecosystem looks, you can’t get around the two most fundamental and most critical blockchain cornerstones: data availability and security.

These two terms may sound technical, but they determine:

• Are your assets truly “under your own control”?

• Can your transactions be verified?

• Will Layer2 suddenly go down or “do evil”?

• Is the public chain’s scaling robust?

• Can developers fully trust the underlying architecture?

If we compare blockchain to a city:

• Security = the city’s public safety system

• DA = whether all public records are open and transparent

• Good public safety, but the ledger isn’t public? — you can still fake things.

• The ledger is transparent, but public safety is bad? — the system will be attacked.

• Only when both exist does the chain become truly trustworthy.

Today, we will use a truly relaxed and easy-to-understand way to thoroughly explain DA and security.

Data availability essentially solves the most fundamental problem: can the on-chain state be verified by all participants? You have to know that the core value of blockchain is “transparency + verifiability,” which means any node should be able to:

• download blocks

• obtain all transaction data

• recompute the state

• fully verify the chain

Only then is a blockchain self-verifiable.

Take Layer2 as an example: L2 processes transactions in its own execution environment, and the final state must be submitted back to L1. But what happens if the submitted data is incomplete?

Users cannot verify
The state cannot be reconstructed
Users cannot “force exit”
The operator can forge transactions
The entire system becomes a centralized database

That is to say, without DA, no matter how high your TPS is, you are not a secure blockchain system.

DA = data must be fully published, remain accessible, verifiable, and reconstructable. It is not simply “whether a server can read it,” but rather:

• all nodes can independently verify

• data will not be intentionally withheld

• users do not rely on the operator

• the whole network has the ability to construct the same state

In other words: without DA, there is no real blockchain.

Traditionally, we thought security was only “resisting attacks.” In fact, complete security includes three layers:

It determines whether the chain can withstand malicious nodes:

• PoW: is the hash power sufficiently decentralized?

• PoS: is the total stake sufficiently large?

• are nodes decentralized?

• can it be exploited by a 51% attack?

The more people jointly maintain the ledger → the harder it is to attack.

A chain must make the cost of attack extremely high, with costs far exceeding potential gains, for example:

• attacking Ethereum requires staking millions of ETH

• attacking BTC requires massive ASIC capability

• attacking Celestia requires a large amount of TIA stake

The higher the cost → the more secure the system.

• are smart contracts trustworthy?

• can state be forged?

• can malicious behavior happen at the contract layer?

• is there off-chain black-box execution?

• can the state root be proven?

Execution security is often where vulnerabilities originate.

Here is the underlying logic that truly affects blockchain security: a blockchain without DA = unverifiable = insecure. This is like a tax system needing an open ledger; a blockchain must make transaction state public. If data is not published on-chain, then the assets you hold cannot even be proven to belong to you.

Let’s use an extremely simple but critically important example.

You hold 10 ETH on an L2, and then the L2 goes down. If:

• the data has been uploaded to L1 (has DA) → you can “force exit,” and the assets can be recovered

• the data has not been uploaded → you can never get your assets back, and you can’t even produce proof

DA is like the “original evidence” of your assets. Without evidence → even the court can’t save you.

In the entire blockchain scaling system, “Data Availability, DA” has always been the most easily overlooked, yet the most critical underlying module. Whether it is Rollups, sharded chains, Appchains, or the latest modular blockchain narrative, the strength of DA almost directly determines a chain’s security, economic model, user experience, and ecosystem scalability.

The industry generally divides DA capability into three major levels. Each level corresponds to a different design philosophy, a different security model, and completely different commercialization scenarios. Below, we will expand comprehensively across six dimensions — architecture design, technical principles, security level, ecosystem prospects, typical projects, and applicable scenarios — so you truly understand the strategic position of the DA sector in the future.

Representatives: Ethereum, Bitcoin (in some scenarios), Celestia (on its own chain)

Layer1 DA is the industry-recognized “gold standard,” and you can even say it is the “gold reserve” of the blockchain world. The reason is only one: thousands, ten thousand, or even one hundred thousand nodes across the network jointly store and verify the same on-chain data. This security comes from strong consensus, from an ultra-dense full-node network, from a globally distributed miner/validator network. Any attacker who wants to tamper with data would have to “break through the entire internet.”

① Data will never be lost: global nodes back it up together Ethereum’s data redundancy is exaggerated:

• full nodes store all block data

• light nodes can sample-verify

• archive nodes preserve historical state

This means that as long as there is still one Ethereum node left in the world, your Rollup data will not disappear.

② Economic security is quantifiable and verifiable

Ethereum’s security comes from the economic model of staked ETH. If an attacker wants to manipulate data, there is only one feasible way: control 51% of validator staked capital. The current cost is as high as tens of billions of dollars, and would also be slashed. This is why Layer1 DA is regarded as an unshakable security foundation.

③ Strongest censorship resistance

The network is distributed across 100+ countries globally, with no single point that can be shut down. No country, institution, or team can unilaterally take data offline.

Drawback 1: extremely high cost

Publishing DA (Rollup Data) is very expensive, for example:

• ETH calldata is costly

• block space is limited

• competition for space pushes gas up

This means: the more your Rollup is used, the more expensive it becomes.

Drawback 2: limited throughput

Ethereum needs to process massive contract calls and transactions every day, leaving relatively limited space for DA.

This type of DA represents a major shift in blockchain design philosophy: “separate execution, settlement, and DA, and let each layer do what it is best at.”

Modular DA is born specifically for scaling. It allows Rollups to no longer rely on Ethereum’s expensive DA, but instead have cheaper, faster, and more scalable data publishing space.

① High throughput + massive data bandwidth

Celestia’s chain achieves horizontal scaling through Data Availability Sampling (DAS).

More nodes = higher DA capability. When the node scale increases, Celestia’s DA throughput can also increase multiplicatively. This is the opposite of L1: traditional L1 becomes slower as there are more nodes, while modular DA becomes faster as there are more nodes.

② Extremely low cost (compared with Ethereum DA)

Taking Celestia as an example: the cost of publishing a piece of DA data is 10–100 times lower than Ethereum. Rollups can use Celestia as the DA layer, while continuing to submit state roots to Ethereum to obtain L1 security (Dual Posting mode). This makes it possible that in the future, all Rollups may migrate to modular DA.

③ Strong decentralization

Modular DA networks also have their own complete validation system:

• validator set

• node network

• light-node sampling verification

• multi-region distributed data storage

It is not a multi-node “centralized database,” but a truly decentralized DA blockchain.

• global Rollups are surging

• more and more Appchains

• L2 costs are entering a price war

• ZK Rollups require massive DA space

• high-data-volume businesses such as MEV, AI, and on-chain games are emerging

In the future, there will be thousands upon thousands of chains that all need DA. This is the super opportunity of modular DA.

Off-chain DA is mainly used by chains pursuing extreme TPS, such as:

• some Solana vendorized fork chains

• high-speed Layer3

• enterprise chains

• game chains

• centralized sidechains

Their core idea is: if data is not put on-chain and only exists on servers, then throughput can be infinitely high.

The composition of off-chain DA usually includes:

• centralized servers

• RPC service providers

• independent data warehouses (such as Data Lake)

• enterprise-grade cloud storage

• no “public validator” system

Off-chain DA is more like Web2, not blockchain.

Because data is in the hands of the operator, if they intentionally hide a block, then:

• users cannot verify

• the state root cannot be reconstructed

• Rollup updates fail

• the chain suffers irreversible damage

• off-chain DA lacks an independent verification mechanism

If a Rollup uses off-chain DA, it means:

• if the operator runs away

• if data is lost

• if servers shut down

• users cannot “force exit” back to the main chain

This risk is extremely fatal.

Off-chain DA is indeed high-performance and low-cost, but the price paid is:

• throughput is great

• decentralization is extremely poor

• censorship resistance is almost none

• if something goes wrong, it is impossible to recover

This is more like a “pseudo-blockchain.”

In the next 5 years, Rollups, AI blockchains, ZK computing, GameFi, and real-time order book systems will all consume massive amounts of DA.

Competition in the DA sector will be:

• who is cheaper?

• who is faster?

• who is more secure?

• who can carry a million-level Rollup ecosystem?

What can be determined is:

• Layer1 DA = value reserve layer

• Modular DA = main battlefield of scaling

Off-chain DA = suitable for centralized high-performance scenarios, but not the Web3 mainstream