1. What is finality in Layer 1 blockchain?
Finality is the ability to guarantee that a transaction or data block on a Layer 1 blockchain that has been confirmed cannot be reversed, altered, or deleted. When a transaction achieves finality, the participating parties can trust that the data has been permanently recorded and can be used as the basis for subsequent activities.
🔑 Read more: Comparing National Layer 1 Blockchains: How NDAChain, EBSI and BSN Lead the Way
For national blockchains and critical data systems, finality is the core element ensuring the reliability of digital identity, data verification, and public services. In practice, not every newly created block is absolutely secure. Some blockchains may experience forks when multiple blocks are created almost simultaneously, causing one branch to be discarded and the transactions on that branch to risk being reversed.
Finality therefore plays the role of defining the moment at which a transaction on a Layer 1 blockchain is considered complete and no longer subject to change.
2. Probabilistic finality
Probabilistic finality is the model in which a transaction on a Layer 1 blockchain does not immediately reach a state of absolute certainty. Instead, the probability of a transaction being reversed decreases gradually as more new blocks are built on top of the block containing that transaction.
Characteristics of probabilistic finality:
Requires multiple block confirmations: The more blocks added to the chain, the harder it becomes to alter or reverse a transaction.
Based on statistical probability: There is no moment of absolute 100% certainty, but the level of security increases over time.
Common on public blockchains: This is the model used by Bitcoin, Proof of Work (PoW), and some Layer 1 blockchains using Proof of Stake (PoS).
🔑 Read more: Comparing PoW, PoS, and PoA: Which Consensus Mechanism for Layer 1 Blockchain?
On Bitcoin, for example, a transaction is typically considered safe after approximately 6 block confirmations, equivalent to nearly 60 minutes. This model suits open blockchain networks with thousands of participating nodes, but must trade off confirmation speed to achieve a high degree of decentralization.
3. Instant finality
Instant finality, also known as deterministic finality is the model in which a transaction on a Layer 1 blockchain is considered complete as soon as the block containing it is confirmed. After this point, the transaction cannot be reversed, altered, or replaced by any other branch of the blockchain.
🔑 Read more: Comparing National Layer 1 Blockchains: How NDAChain, EBSI and BSN Lead the Way
Characteristics of instant finality:
Near-immediate confirmation: A transaction reaches its final state as soon as the block is approved by validators.
No temporary forks: The blockchain maintains a single chain, with no competing branches as seen on many public networks.
High reliability: Suited to systems requiring absolute accuracy and auditability.
Common in BFT mechanisms: A defining feature of consensus algorithms such as PBFT, qBFT, and Layer 1 blockchains using licensed validator models.
According to the Ethereum Foundation's documentation on finality, modern consensus mechanisms are increasingly moving toward fast and deterministic finality to improve user experience and reliability.
4. How does the national blockchain achieve near-instant finality?
As a national Layer 1 blockchain, NDAChain uses the PoA-qBFT (Proof of Authority - Quorum Byzantine Fault Tolerance) consensus mechanism to achieve near-instant finality. When a block receives consensus from more than two-thirds of the validators in the network, the transactions inside that block are confirmed as final and cannot be reversed.
NDAChain's key performance indicators:
Block creation time: 2 seconds (± 0.2 seconds)
Confirmation latency: under 2 seconds
Near-instant finality: no need to wait for multiple block confirmations as in Proof of Work blockchains
High performance: supports 1,200–3,600 transactions per second (TPS)
🔑 Read more:Vietnam’s National Blockchain Platform Surpasses 5 Million Verified Transactions
Thanks to the PoA-qBFT mechanism, NDAChain combines high processing speed with transaction certainty, creating the foundation for digital identity, data verification, and public service applications on the national blockchain without having to trade off between performance and reliability.
5. Why is instant finality important for national blockchain?
For national blockchains and critical data systems, instant finality is not merely a technical advantage, it is a mandatory requirement to ensure reliability and operational efficiency.
The standout benefits of instant finality include:
Legal certainty assurance: Transactions involving digital identity, data verification, electronic certificates, or citizen records must be conclusively confirmed and irreversible.
Faster processing times: Citizens, enterprises, and regulatory agencies receive results almost immediately, without waiting through multiple layers of confirmation.
Elimination of transaction reversal risk: No transactions are cancelled due to forks or chain reorganizations as on blockchains using probabilistic finality.
Support for real-time operations: Suited to applications such as traceability, credential verification, electronic contracts, and inter-agency data sharing.
This is also one of the key reasons NDAChain, in its role as the national Layer 1 blockchain, chose the PoA-qBFT mechanism to achieve near-instant finality, meeting the requirements of reliability, performance, and data sovereignty at national scale.
6. Finality and the trust foundation of national blockchain
Finality is one of the most important factors determining the reliability of a Layer 1 blockchain, yet it is often overlooked when evaluating blockchain technology. At its core, finality answers the fundamental question: when is a transaction truly complete and no longer reversible?
With probabilistic finality, users must wait for additional block confirmations to increase transaction certainty. Instant finality, by contrast, allows a transaction to become final as soon as it is confirmed by the consensus mechanism.
For a national blockchain like NDAChain, serving digital identity, data verification, traceability, and public services, transaction certainty is a mandatory requirement. Thanks to the PoA-qBFT mechanism, NDAChain achieves near-instant finality, enabling data to be confirmed quickly, irreversibly, and with transparent verifiability. This is the foundation of digital trust for national-scale data infrastructure and digital transactions.
7. Frequently asked questions about finality in Layer 1 blockchain
7.1 What is finality in blockchain?
Finality is the guarantee that a transaction or data block on a Layer 1 blockchain that has been confirmed cannot be cancelled, reversed, or altered. When a transaction achieves finality, participating parties can be confident the data has been permanently recorded and can be used as the basis for subsequent activities. This is the core factor determining the reliability of a national blockchain and digital transaction infrastructure.
7.2 How do instant finality and probabilistic finality differ?
Probabilistic finality is the model where a transaction becomes increasingly certain as more block confirmations are added Bitcoin typically requires around 6 blocks, equivalent to 60 minutes. Instant finality is the model where a transaction becomes final as soon as the block is confirmed by the consensus mechanism, with no need to wait for additional blocks, as in BFT mechanisms. Instant finality is faster and more certain, but suits networks with a defined validator set.
7.3 Does NDAChain have instant finality?
Yes. NDAChain achieves near-instant finality through PoA-qBFT, belonging to the Byzantine Fault Tolerance family. When a block receives commitment from more than two-thirds of the 49 public-private validators, the transaction is immediately final. NDAChain has a block creation time of 2 seconds and a latency of 1.5 seconds, with no need to wait for multiple block confirmations.
7.4 Why does Bitcoin need to wait for multiple block confirmations?
Because Bitcoin uses Proof of Work with probabilistic finality, where a transaction only becomes increasingly certain as more blocks are stacked on top. Bitcoin can experience temporary forks, where one branch is discarded and transactions on it are reversed. The standard practice is to wait for approximately 6 blocks equivalent to 60 minutes for a transaction to be considered safe.
7.5 Why is instant finality important for public services?
For public services, instant finality ensures legal certainty transactions verifying documents or issuing certificates are final immediately, delivers a fast user experience, eliminates the risk of transactions being reversed on a discarded branch, and supports real-time operations such as traceability. This is why NDAChain chose a BFT mechanism over PoW.
