Scalability remains one of the key challenges for blockchain technology. In this context, layer 2 (L2) solutions play an essential role by increasing the capacity of networks without compromising the security of the main layer (L1). A few months ago, we analyzed the role of layers L1, L2 and L3, laying a solid foundation for understanding the different scaling techniques. Now the focus turns to rollups and their variants, and how they efficiently address scalability challenges. This analysis will also serve as a prelude to future articles that will explore the different types of rollups in greater depth.
What are rollups?
Rollups are L2 scaling solutions designed to increase the transactional capacity of a blockchain. Their primary function is to bundle multiple off-chain transactions into a single package and then process them as a single transaction on the main chain. Instead of the L1 validating each transaction individually, it only validates a cryptographic proof that guarantees the veracity of the set of transactions. This significantly reduces the amount of data processed and stored on the main chain, improving both the speed and cost of transactions for users.
The concept behind rollups is to maximize efficiency without compromising security. By processing transactions off-chain and publishing only a summary of the results, the workload on the main chain is reduced, helping to prevent network congestion. However, there are different types of rollups that use different methods to validate these transactions.
Types of Rollups
There are two main types of rollups that differ primarily in the cryptographic methods they use to validate transactions: optimistic rollups and zero-knowledge rollups (ZK rollups).
Optimistic Rollups
Optimistic rollups operate on a “presumption of validity” principle, assuming that all off-chain transactions are valid unless proven otherwise. Only when the validity of a transaction is questioned must validators provide evidence of fraud, which is then verified on the main chain. If a transaction is found to be invalid, it can be reversed and the perpetrator is punished through a slashing mechanism.
The optimistic rollup process is based on the publication of a proof called the state root, which summarizes the final state of all processed transactions. This proof is sent to the main chain, and during a challenge period, any participant in the network can challenge the validity of the transactions. If a challenge is valid, the fraudulent transactions are re-executed, the status is adjusted accordingly, and the responsible party is penalized. Otherwise, if the challenge period expires without a challenge, the transactions are considered valid.
Zero Knowledge Rollups (ZK-Rollups)
On the other hand, ZK rollups use cryptographic proofs, called zero-knowledge proofs, to prove the validity of transactions without revealing transaction details. This technique provides both security and privacy, since validators do not need to know the exact content of transactions to verify their validity.
The distinguishing feature of ZK rollups is their ability to guarantee the validity of transactions immediately, eliminating the need for a challenge period and the potential delays it introduces. In addition, ZK rollups are virtually immune to attack because it is extremely difficult to create a false zero-knowledge proof. In short, ZK rollups provide a more efficient and secure solution with a high level of user privacy.
Within ZK-rollups there are two basic technologies:
- ZK-SNARKs (Succinct Non-Interactive Argument of Knowledge): These zero-knowledge proofs are compact and efficient in terms of verification, making them an ideal choice for applications where speed and small size are critical. However, they require a trusted setup, which introduces a potential security risk if the setup is compromised.
- ZK-STARKs (Scalable Transparent Argument of Knowledge): This technology is an evolution of ZK-SNARKs and eliminates the need for a trusted setup. ZK-STARKs are more scalable and are designed to be resistant to quantum attacks, making them more secure in the long run. Although their size and verification speed are less efficient than ZK-SNARKs, they offer greater transparency and security, making them a robust choice for applications that require scalability and strong cryptographic protection.
Both technologies play a key role in the implementation of ZK rollups, providing a cryptographic infrastructure that not only ensures the validity of transactions, but also protects the integrity of the data.
Conclusion
As the demand for faster and more efficient blockchain networks continues to grow, rollups are emerging as a viable solution to address the bottlenecks and bloat that have limited network performance. With the ability to efficiently and securely process large volumes of transactions, both optimistic rollups and ZK rollups offer different approaches to effectively scale networks.
Due to its popularity and resources, Ethereum is the blockchain that has made the most progress in developing and optimizing these technologies. Effective implementation of rollups will allow this and other networks to improve the user experience and make transactions faster and cheaper, without compromising security or decentralization.
Therefore, understanding and exploring different scaling technologies is key to the future of the blockchain. Rollups represent a breakthrough in this regard, and their large-scale adoption could mark a new era in the evolution of distributed networks.
In the next articles, we will delve into the specific workings and features of optimistic rollups, then explore ZK rollups in detail, and finally compare the two technologies to provide a more comprehensive view of their applicability and potential.
Resources:
[1] Ledger – What are blockchain rollups
[2] Hackernoon – Optimistic rollups vs zk rollups
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