Can Pi Squared become the next generation of verifiable computing paradigm?

The widespread application of cloud computing is primarily determined by its credibility. In practical applications, all data on cloud computing must be complete, and during program execution, it must have high accuracy, which can effectively broaden the application scope of cloud computing. Additionally, cloud computing protocols can assess all feedback results within the server, and remote servers do not need to reoperate related programs. In recent years, verifiable computing has received significant attention from researchers and has become a major trend in the development of trustworthy cloud computing.
Pi Squared, led by Grigore Rosu, a computer science professor at the University of Illinois Urbana-Champaign, is dedicated to achieving verifiable computing through zero-knowledge technology. The core idea of Pi Squared stems from Rosu's years of research in academia, where he and his students explored this technology over the years, ultimately forming the concept of Pi Squared.

Industry insiders believe that if Pi Squared succeeds, it will completely revolutionize verifiable computing. This technology will not only be used for the Universal Settlement Layer (USL) of blockchain but will also extend to the fields of scientific and knowledge verification, applicable to all languages and virtual machines, inherently correct and high-speed.

It can be said that the application scenarios and value space of Pi Squared are highly imaginative.
Before delving into Pi Squared, it is necessary to understand several other innovative projects based on ZK technology and their differences and connections with Pi Squared.

01

Competitive Analysis

ZKsync
ZKsync is an Ethereum scaling solution that utilizes ZK-rollup technology to achieve high throughput and low transaction fees. It achieves scalability by batch processing multiple transactions and generating ZK proofs. The main advantages of ZKsync are its significantly reduced transaction speed and fees while maintaining Ethereum's security.
ZK-native
ZK-native refers to blockchains that adopt zero-knowledge proof technology from the ground up. These blockchains typically have stronger privacy protection and data compression capabilities, such as StarkNet and Mina Protocol. They ensure the privacy and efficiency of transactions and data by directly integrating ZK technology at the protocol level.
ZK Chain
ZK Chain refers to blockchain systems that use zero-knowledge proof technology as a core component. These systems are typically designed to enhance privacy protection and scalability, such as Aztec and Zcash. ZK Chain provides users with strong privacy protection and efficient transaction processing capabilities by utilizing technologies like ZK-SNARK or ZK-STARK.

The main difference between Pi Squared and the aforementioned technologies lies in its universality and verification method. While ZKsync, ZK-native, and ZK Chain focus on improving the performance and privacy protection of specific blockchains, Pi Squared offers a universal verifiable computing solution for all blockchains, virtual machines, and programming languages through its Universal Settlement Layer (USL). The PoP technology of Pi Squared is not only applicable to blockchain but can also extend to other computing fields, achieving true universal computing.

02

USL: The Secret Weapon of Pi Squared

Pi Squared's first product is the Universal Settlement Layer (USL), which is a modular blockchain architecture with the following core features:
(1) Universality
USL supports computations in any language or virtual machine without the need for a compiler. This means developers can use their familiar programming languages for blockchain transaction settlements.
(2) Provable Correctness
USL verifies the correctness of computations through mathematical proofs, allowing any external entity to independently verify the correctness of the USL state.
(3) Minimal Trust Base
USL transparently exposes the trust assumptions in upper-layer computations, ultimately minimizing the trust base through correctness proofs, increasing user trust and transparency.
(4) Application Interoperability
USL supports interoperability between different application modules and networks, such as interactions between appchains.
(5) Determinism and Repeatability
The verification process of USL is deterministic, allowing any external entity to independently repeat the verification.
The USL architecture of Pi Squared consists of multiple layers and components, each playing an important role in achieving efficient and verifiable computations.
First, the Computing Layer
The computing layer is at the top of the architecture, where various languages and virtual machines execute computations. It includes transaction execution engines, fully functional application chains, and executing rollups. The computations in the computing layer can be very complex, and the environment can implement its own optimizations and parallel processing, with USL not needing to understand how these computations are executed.
Second, the Sequencer Network
The Sequencer Network is responsible for processing transactions between the computing layer and USL. Sequencers validate and collect transactions into blocks, facilitating efficiency and increasing transaction throughput. The Sequencer Network is typically decentralized and runs consensus algorithms to securely order transactions. The pre-confirmation at the Sequencer Network layer is optimistic and can revoke invalid transactions after USL verification.
Third, the Execution Layer Interface
The execution layer interface is located below the computing layer, enabling the computing layer system to communicate with USL. It accepts "computational transactions," including transactions, state changes, and transitional metadata. The metadata defines the program for executing computations, the list of trusted entities, and other details.
Fourth, the USL Layer of Pi Squared
The USL layer operates as an optimistic rollup, interpreting computational transactions as mathematical statements in logical theories. USL generates mathematical proofs of the computation sequence to ensure correctness, primarily consisting of the π² network and the Prover Pool.
Finally, the π² Network and Prover Pool
The π² network consists of nodes running consensus protocols that verify the validity of the state after transaction verification. The verification process is transparent and repeatable, allowing any external entity to independently verify it. The Prover Pool consists of prover nodes that generate zero-knowledge proofs (ZKP) for transactions or blocks. ZKP is achieved by re-executing transactions or blocks and generating matching logical correctness proofs. The generated ZKP is much smaller than the original mathematical proof, allowing for faster transmission and verification.

03

The Application Value of USL in the Web3 Field

The Pi Squared team envisions USL as a language and virtual machine-agnostic layer that will significantly enhance cross-chain applications and liquidity access in the Web3 industry. Specific applications include:
Rollup-in-a-box
This service supports the creation of L2/L3 rollups and application chains, allowing users to choose system features, with all transactions transparently settled by USL.
Multi-chain bridging
Multi-chain bridging enables applications and rollups running on USL to seamlessly bridge tokens across different chains without off-chain code.
Cross-chain financial applications
USL allows DeFi applications to smoothly transition between different rollups and application chains, providing better staking and lending rates. For example, staking ETH on Ethereum and borrowing USDC on the Cosmos chain.
Heterogeneous ZK verification
Users can leverage various ZK rollups and applications supported by USL, choosing the ZK platform they are familiar with, while USL verifies transactions through the corresponding ZK backend.

Summary

With its innovative PoP technology and Universal Settlement Layer (USL), Pi Squared has set a new benchmark in the field of verifiable computing. USL not only addresses many challenges in the current blockchain ecosystem but also lays the foundation for future scientific and knowledge verification.
Although USL performs excellently in many aspects, it also has some limitations, such as: USL does not aim to enhance privacy, only maintaining the confidentiality of the matching logical proofs of computational correctness. Future considerations may include the privacy needs of specific applications; the transaction structure allows specifying a list of trust dependencies, defined by system components. USL will not proactively discover the trust base of transactions lacking trust dependency specifications, initially focusing on trust base verification.
However, the significant breakthroughs achieved in its technology demonstrate USL's ability to solve practical problems in practice. In the future, with the rise of more applications and the improvement of infrastructure, Pi Squared is bound to bring more innovations and transformations to the blockchain industry.