Polkadot GRANDPA: The Foundation of Blockchain Security

At P2P.org, we take blockchain security seriously.

Executive Summary:

Blockchain security is a top priority for validators, especially with the expansion of Polkadot's active validator set. Validators are vital in securing the network by participating in block production and finalization processes. However, some validators bypass GRANDPA participation to reduce operational costs, jeopardizing network stability and security.

Active block production and finalization participation are crucial for maintaining Polkadot and Kusama's network integrity. Validators who avoid GRANDPA undermine network performance, potentially leading to slower finalization and reduced reliability. To mitigate these risks, token holders should carefully evaluate validators based on their commitment to security, uptime, risk management, and compliance with industry standards.

P2P.org offers tools like the Relay Participation Rate dashboard to monitor validator engagement, helping stakeholders make informed decisions. By delegating stakes to validators prioritizing network health and security, token holders can contribute to a more resilient and trustworthy blockchain ecosystem.

Understanding Blockchain Security

With the recent referendum aiming to expand the active validator set to 400, the focus has intensified on the critical role validators play in securing the Polkadot network—especially through their participation in finalizing blocks. Validator engagement in the consensus process is essential for maintaining the integrity of the ecosystem, and upholding high operational standards has never been more crucial.

In Polkadot, block production begins with the Blind Assignment for Blockchain Extension (BABE) protocol. BABE randomly assigns validators to produce blocks in slots approximately every six seconds. Validators participate in this random lottery for each slot, producing a block if selected. Notably, a backup validator is also assigned in case the primary validator fails to produce a block.

Once a block is created, it needs to be finalized by other network participants—precisely, the validators—through the GRANDPA (GHOST-based Recursive ANcestor Deriving Prefix Agreement) finality gadget. GRANDPA operates in parallel with block production as an independent process. Validators engage in consecutive rounds of voting to finalize blocks, and once two-thirds of the validators have voted in favor, the block is considered final.

While validators cannot influence the BABE step due to its randomness, they are incentivized to participate in block production because they receive rewards for creating blocks. However, the same incentive structure does not apply to GRANDPA participation. This lack of direct monetary reward can tempt some validators to disable their participation in GRANDPA by running their nodes with the --no-grandpa flag, potentially reducing operational costs at the expense of network security.

Why Validator Participation in GRANDPA Matters

Skipping finalization might lower operational expenses—such as bandwidth consumption and node maintenance—but it introduces significant risks to the network. Without robust participation in GRANDPA, the network may experience delays in finalizing blocks, adversely affecting performance and reliability. The ecosystem's security is intrinsically linked to the consistency and reliability of validators in the finalization process.

Moreover, validators who avoid participating in GRANDPA place additional burdens on those who maintain high operational standards. These standards are often achieved through rigorous internal monitoring, adherence to compliance frameworks, and dedicated infrastructure management. Validators committed to these practices ensure consistent uptime and mitigate risks such as slashing, thereby contributing to a more secure and resilient network.

The Current State of Participation

Our public dashboard, Relay Participation Rate (accessible via Telegram authentication), offers an overview of validator participation in the finalization process across Polkadot and Kusama. This tool is part of our Monitoring as a Service (MaaS) project, designed to provide validator operators in Substrate-based networks with transparency and monitoring capabilities. To access the dashboard, login with your Telegram account, navigate to the "General" section in the upper left-hand corner, and select "Relay Participation Rate."

The dashboard features three types of charts:

Prevotes Ratio: Indicates participation in the first part of the consensus process.
Precommits Ratio: This ratio relates to GRANDPA (chain finality) and represents how often a validator participates in finality, the second part of the consensus.
Missing Backing Votes Ratio: Shows the percentage of skipped candidate backing actions (Proof of Validity) for parachains—the most profitable aspect of a validator's activity.

The top table provides a current snapshot of validators and their participation ratios in the consensus process. While the Polkadot network currently shows no validators with 0% precommits (finality stage), several validators exhibit low engagement. This could signal infrastructure issues or deliberate decisions to minimize costs at the expense of network security.

On Kusama, the situation is more concerning. As of September 11, 20 validators displayed 0% participation in both prevotes and precommits, raising questions about their reliability and commitment to network security. Such inconsistent participation—whether due to inadequate infrastructure or intentional non-participation—can undermine the overall stability of the ecosystem.

The Risks of Non-Participation

A decline in validator participation poses a risk of slower finalization times, which can have cascading effects on both the Polkadot and Kusama ecosystems. Maintaining at least two-thirds participation is essential for the network's smooth functioning. If a significant number of validators continue to prioritize cost-cutting over participation in finalization, the network's reputation and its ability to attract further development may be jeopardized.

It's important to note that GRANDPA's non-participation is neither financially rewarding nor subject to slashing penalties. This lack of immediate consequences provides little motivation for validators to engage in the finalization process, highlighting the need for token holders to be vigilant in their choice of validators.

How to Choose Reliable Validators

Given these potential risks, it's imperative for token holders to thoroughly evaluate validators before delegating their stakes. Key factors to consider include:

Commitment to Network Security: Does the validator consistently participate in both block production and finalization processes?
Uptime Track Record: Does the validator maintain high availability, ensuring the network remains robust and responsive?
Risk Mitigation Measures: Does the validator implement safeguards against slashing and other operational risks?
Compliance with Industry Standards: Has the validator undergone third-party audits, such as SOC 2, to verify their adherence to security and operational protocols?
Infrastructure Quality: Does the validator invest in reliable, secure infrastructure to support their operations?

Delegating to validators prioritizing network health through consistent participation and reliability strengthens the Polkadot and Kusama ecosystems. Validators that uphold high-performance standards and implement comprehensive security measures—such as internal compliance audits, uptime guarantees, and slashing protection—offer a more robust and secure environment for stakers.

By choosing validators committed to the network's long-term health and security, token holders can contribute to a more resilient and trustworthy blockchain ecosystem.

Do not hesitate to ask questions in our Telegram chat or contact Alex via aleksandr.tishin@p2p.org. We are always open to communication.

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