Merkle-ized Operational CRDTs for Mutability on a Solana Layer 2: Without Consensus or Native Tokens

The engineers at Pipe Network want to share their research and insights on Layer 2 blockchain environments.

In decentralized systems, balancing scalability, security, and performance is a complex challenge, especially when handling mutable data in real-time. One of the most promising solutions to achieve this balance is the use of Merkle-ized operational Conflict-free Replicated Data Types (CRDTs), particularly in Layer 2 (L2) environments that do not rely on traditional consensus mechanisms or native tokens.

But when you remove consensus and native tokens, how do you address critical concerns like Distributed Denial of Service (DDoS) attacks and transaction spam? These threats are typically mitigated through mechanisms like staking, token-based fees, or other economic disincentives. In this blog post, we’ll dive deeper into how Merkle-ized CRDTs combined with the architecture of Solana Layer 1 can help mitigate these risks while keeping the system lightweight and efficient.

CRDTs for Scalability and Mutability Without Consensus

As outlined earlier, CRDTs allow decentralized replicas to update data independently and concurrently. They ensure that even in a distributed environment, all replicas eventually converge to the same state, removing the need for heavy consensus mechanisms.

• Operational CRDTs: These CRDTs transmit operations (such as data updates) across replicas. The operations are merged deterministically, so there’s no need for global ordering, reducing overhead and enhancing performance. This ensures that updates happen rapidly without bottlenecks.

• No Consensus: Since CRDTs naturally resolve conflicts through deterministic merging of operations, there’s no need for consensus protocols like those used on Layer 1 chains (e.g., Proof of Stake). This significantly lowers the computational and economic costs of maintaining the L2, allowing for faster, more scalable systems.

However, while CRDTs solve the problem of decentralized mutability, they don’t inherently provide protection against malicious behavior, such as DDoS or spam attacks. For that, we turn to Merkle trees and Solana Layer 1.

Merkle Trees: Cryptographic Verifiability and Proof

Merkle trees offer cryptographic guarantees that can ensure data integrity and secure state verification, even in decentralized environments.

• Merkle-ized Operations: Every operation that modifies the state of a CRDT is hashed and included in a Merkle tree. This means that a compact cryptographic proof can be generated for any given operation, which allows the entire network to verify whether a particular operation is valid and part of the overall dataset.

• Anchoring on Solana: Without an L2 consensus mechanism, the periodic anchoring of Merkle roots to Solana’s Layer 1 chain can serve as a secure audit log. This ensures that the operations executed on the L2 are valid and cryptographically verifiable without relying on a consensus mechanism for each individual operation.

While Merkle trees ensure that only valid operations are included, they do not directly address concerns like DDoS attacks or transaction spam. But by anchoring periodically to Solana L1, the L2 can leverage the security and high-throughput properties of Solana for additional layers of protection.

DDoS and Transaction Spam Protection in a Token-less L2

One of the key challenges of removing consensus and native tokens is the potential exposure to DDoS attacks and transaction spam. These threats can overwhelm the system by submitting a high volume of operations, potentially causing performance degradation or even downtime.

Here's how these risks can be mitigated:

1. Rate Limiting at the Node Level

Each node participating in the L2 can implement rate limiting to prevent spam or DDoS attacks. By limiting the number of operations that can be processed in a certain time period, nodes can ensure that no single user or group of users can flood the system with excessive operations. This can be done through several approaches:

• IP-based Rate Limiting: Nodes can track the number of operations submitted by each IP address and limit submissions once a threshold is crossed.

• Geolocation-based Limiting: In addition to IP-based limits, nodes could apply rate limits based on geographic regions to prevent regional attacks or concentration of operations.

Even in a decentralized environment, node operators would have the incentive to protect their own resources from being overwhelmed, ensuring system stability and uptime.

2. Merkle-based Proofs for Valid Operations

In conjunction with rate limiting, Merkle proofs can be used to discard invalid or spammy operations before they even hit the network. Each operation is cryptographically hashed and included in a Merkle tree, and only operations with valid proofs are propagated across nodes.

This mechanism is key for preventing transaction spam because it ensures that only valid, provable operations are added to the CRDT state, thereby reducing the attack surface for spamming operations.

3. Periodic Checkpointing and Finality on Solana Layer 1

To further secure the L2 from malicious activities, periodic checkpointing on Solana Layer 1 can act as a “finality” layer for operations. By anchoring Merkle roots on Solana’s high-throughput L1, you create a system in which the L2 only has to interact with the L1 occasionally, but these interactions ensure the integrity of operations in the face of spam or DDoS attacks.

• Checkpoint Frequency: You can configure how often Merkle roots are anchored to Solana, balancing between overhead costs and security. A higher frequency means more immediate verifiability, while a lower frequency reduces costs but still ensures eventual security and finality.

This periodic anchoring ensures that spam operations that do slip through are quickly caught and pruned out at the finality checkpoint, limiting their impact.

No Native Token: Lightweight Operations Without Fees

One of the biggest benefits of this design is the absence of a native token on the L2. Most L2s use native tokens to handle transaction fees and incentivize node operators. However, by combining Merkle-ized CRDTs with periodic anchoring on Solana, we can avoid the need for a token-based fee system entirely.

• No Transaction Fees on L2: Since the operations are handled by CRDT replicas and verifiability is ensured through Merkle proofs, there’s no need to charge users for every operation. This makes the system more accessible and scalable.

• Solana Fee Structure: Any necessary fees are pushed to Solana Layer 1 when Merkle roots are anchored. This way, users only pay fees when anchoring checkpoints to the more secure Solana network, ensuring cost efficiency.

Without the overhead of token-based transaction fees, the L2 becomes a lightweight platform, ideal for applications that need rapid, frequent updates, such as decentralized file systems, NFT metadata, or collaborative tools.

Potential Use Cases

This architecture has many potential applications that require decentralized mutability, scalability, and security against attacks:

• Collaborative Editing: A decentralized Google Docs alternative could use this L2 design, with users able to edit documents in real-time without paying transaction fees for each update.

• Decentralized File Storage: Dynamic, mutable metadata for decentralized file storage (e.g., IPFS, Arweave) could benefit from this lightweight system, ensuring security without consensus overhead.

• Dynamic NFTs: NFTs that evolve over time or require mutable metadata (e.g., game assets or dynamic art) could leverage this architecture for secure, scalable updates.

Challenges and Considerations

While this approach brings a lot of benefits, there are some challenges and limitations to consider:

• Malicious Actors: Since there’s no consensus on the L2, there’s a risk of malicious actors introducing invalid operations. This risk can be mitigated by the anchoring of Merkle roots to Solana L1, but it’s still a factor that requires careful consideration.

• Forks and Divergence: CRDTs guarantee eventual consistency, but temporary forks could occur if replicas diverge for an extended period before anchoring. Developers will need to design strategies to resolve forks gracefully.

Conclusion

By using Merkle-ized operational CRDTs on a Solana Layer 2 without consensus or native tokens, we achieve a system that is not only scalable and mutable but also secure against DDoS attacks and transaction spam. Rate limiting, cryptographic Merkle proofs, and periodic checkpointing on Solana Layer 1 provide robust protection against malicious activity, even in a token-less environment.

This hybrid architecture offers a lightweight, efficient solution for decentralized applications that require mutability, while remaining secure and resistant to abuse. As blockchain technology evolves, solutions like these will be key to unlocking the next generation of decentralized, scalable, and secure applications.