Atleta: The Secure, Decentralized Multi-Layer Blockchain Network

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Dec 12, 2024

Blockchain

Uncovering GRANDPA—GHOST-based Recursive Ancestor Deriving Prefix Agreement

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Producing blocks in blockchain is one thing, ensuring they’re unchangeable is another. That’s where GRANDPA steps in. Today, we uncover how GRANDPA works, what makes it unique, and why it’s important for ATLETA Network.

What is GRANDPA?

GRANDPA, short for GHOST-based Recursive Ancestor Deriving Prefix Agreement, is ATLETA’s finality gadget. It watches that blocks added to the blockchain are permanent and unchangeable.

How does GRANDPA work?

Everything starts with voting. GRANDPA’s voting mechanism has two major steps:

— Prevote phase: Validators cast votes for the highest block they consider valid. This vote also implicitly supports all ancestors of that block, creating a chain of agreement.

— Precommit phase: Validators follow up their prevotes with precommits, formalizing their decision. This means validators don’t change their choice arbitrarily.

When a two-thirds majority of validators precommit to the same block, it and all its parent blocks are finalized.

Then, comes finalizing chains. GRANDPA finalizes an entire chain up to the agreed block. Example: If Block 120 is finalized, all preceding blocks (e.g., Blocks 119 to 1) become finalized simultaneously.

Features of GRANDPA

Accountable Safety

When validators act maliciously, such as double-voting on conflicting chains, they are punished by losing their staked tokens. So, any attempt to undermine the network’s integrity comes with severe consequences and malicious actions become risky and economically unfeasible.

Why it matters: Stake slashing not only deters bad behavior but also assures network participants that their transactions are secure.

Byzantine Fault Tolerance

GRANDPA realizes Byzantine Fault Tolerance (BFT) by requiring a supermajority (two-thirds or more) of validators to agree during voting. Even if up to one-third of validators act maliciously or fail, the remaining honest validators can still reach a consensus.

How it works:

— Malicious validators are unable to form their supermajority due to their minority status;

— Validators' votes are logged and verified, preventing equivocation (voting inconsistently);

— Accountability mechanisms, like stake slashing, deter validators from misbehaving.

Chain-Wide Finalization

Chain-wide finalization means that GRANDPA finalizes not just a single block but an entire sequence of blocks at once.

This process is efficient because it avoids the need to finalize each block individually. This saves time and computational resources. Useful for networks handling large transaction volumes, like ATLETA.

Adaptability to Disruptions

During a disruption, validators may lose communication, causing delays in reaching a consensus. However, GRANDPA adapts by finalizing large batches of blocks once the network stabilizes.

— During disruptions, blocks are produced but may not be finalized immediately;

— After disruptions, GRANDPA uses its voting mechanism to finalize all valid blocks created during the disruption in a single round.

Low Message Overhead

Some systems call for validators to send numerous messages for every block, which can overwhelm the network, especially as it grows.

GRANDPA minimizes this issue because:

— Validators vote on chains, reducing the number of needed messages;

— It finalizes multiple blocks at once, so fewer rounds of communication are expected.

GRANDPA’s features—accountable safety, Byzantine fault tolerance, chain-wide finalization, adaptability, and low message overhead—make it a modern finality instrument, more efficient than other mechanisms.

GRANDPA in Comparison to Alternative Mechanisms

Ouroboros Praos

Ouroboros Praos uses randomness to assign validators for block production. Blocks are added quickly, and safety is concluded probabilistically: the more blocks follow a given block, the less likely it is to be reversed. Good for producing a steady flow of transactions but insufficient for absolute guarantees.

GRANDPA adds deterministic finality. Once validators vote to finalize a block, it and all its predecessors become irreversible.

Tendermint

Tendermint orders validators to exchange messages and agree on each block as it’s produced. This method is excellent for setting immediate finality. Yet, it has a major drawback: the number of messages increases as the network grows.

GRANDPA, instead of finalizing blocks one by one, finalizes entire chains at once. This reduces the number of messages, allowing GRANDPA to scale as the network grows.

Proof of Work (PoW)

Proof of Work relies on miners solving complex mathematical puzzles to produce blocks. This process craves computational power and energy. Plus, PoW provides only probabilistic finality. Blocks become more secure as more blocks are added, but there is always a small chance they could be reversed if an attacker controls enough mining power.

In contrast, GRANDPA signs deterministic finality. When GRANDPA finalizes a block, it and all its ancestors are recorded onto the blockchain. Besides, this certainty is earned through validator voting rather than mining, making GRANDPA more energy-efficient.

Aura

Aura is a deterministic round-robin mechanism for block production. Validators take turns producing blocks in a predictable sequence. The predictability of Aura’s validator assignments can be exploited by attackers, who might target specific validators during their turn.

GRANDPA avoids this pitfall through its voting-based approach and randomized validator assignments (via BABE).

GRANDPA in ATLETA

At ATLETA, the synergy of BABE and GRANDPA forms the foundation of our Nominated Proof of Stake (NPoS) consensus mechanism, blending rapid block production with unshakable finality. BABE preserves fairness and speed in creating blocks, while GRANDPA locks them into the blockchain, finalizing entire chains with deterministic guarantees.

Together, they create a fast, secure, and resilient network, perfect for the changing demands of the sports industry. With BABE and GRANDPA, ATLETA delivers a blockchain built for trust, scalability, and innovation.