StealthScape

StealthScape is a cross-chain, compliant Layer 2 solution designed for private transactions on blockchain networks. It utilizes advanced cryptographic techniques, such as zero-knowledge proofs and ring signatures to provide secure and private transactions while maintaining regulatory compliance.

Such as Bitcoin, the platform is built on a UTXO (Unspent Transaction Output) model, which enhances transaction privacy by avoiding linkability between transactions. StealthScape is also a plasma application for scalable and secure off-chain transactions, ensuring it can handle a high volume of transactions efficiently.

Technically, StealthScape nodes are developed using Rust for core logic and TypeScript for cryptographic operations. It employs the Lightning Memory-Mapped Database (LMDB) for efficient data management and RiscZER0 for generating zero-knowledge proofs to validate the state on the supported blockchains without revealing sensitive data. The platform supports cross-chain functionality, allowing it to integrate with any EVM-compatible blockchain by deploying a smart contract on the target chain.

StealthScape includes a compliance stack with built-in KYC processes to ensure regulatory compliance before transactions are executed, with plans to integrate further compliance tools. For wallet integration, the platform uses a custom Metamask SNAP to facilitate seamless on-chain interactions and significantly improve the user experience.

Currently, the network operates in Proof of Authority (PoA) mode as a proof of concept for ETHOnline 2024. While the project is in its early stages and contains potential weaknesses, it provides a foundational framework for confidential and compliant blockchain transactions across multiple chains.

StealthScape is built as a cross-chain, compliant Layer 2 solution designed to enable private transactions across multiple blockchains. The project combines advanced cryptographic technologies, scalable architectures, and existing blockchain ecosystems. Here’s a breakdown of how it was constructed:

For the core logic, we used Rust, a programming language chosen for its performance, memory safety, and concurrency capabilities. Rust is well-suited for handling complex cryptographic operations and secure transaction processing, which are essential for a privacy-focused blockchain platform. It manages the fundamental transaction logic, state management, and integration with various cryptographic libraries. Alongside Rust, we used TypeScript to handle frontend cryptographic operations and interactions with the blockchain network. TypeScript was selected for its compatibility with popular blockchain development tools, like Metamask, and its ease of use for implementing web-based cryptographic operations.

To manage data storage efficiently, we integrated LMDB (Lightning Memory-Mapped Database), which provides high-speed read access and low-latency storage capabilities. LMDB helps handle the data required for generating and validating transactions, ensuring minimal performance overhead even when dealing with large datasets. We also utilized the RiscZER0 library to generate zero-knowledge proofs (ZK proofs), which validate the correctness of transactions without revealing any sensitive details. RiscZER0 is particularly suited for generating efficient ZK proofs for state verification, a key requirement for maintaining privacy while ensuring compliance and correctness.

For enhanced privacy, StealthScape incorporates Monero's ring confidential transactions (RingCT), a cryptographic technique that obscures the sender's identity by masking it with a group of other potential signers. This method ensures that each transaction remains untraceable while maintaining high security standards. To maintain regulatory compliance, StealthScape integrates a KYC (Know Your Customer) stack. The compliance design is modular, allowing future integrations with different KYC providers and regulatory frameworks. This approach ensures that StealthScape can adapt to evolving regulatory requirements while maintaining user privacy and security. The cryptographic features of StealthScape allow any user to easily create proofs for third parties. For instance, that they spend or not a certain utxo, or that they have or have not a certain amount of funds. Those proofs are allowed by the ring signature scheme we used: Multi Layered Linkable Spontaneous Anonymous Group (MLSAG).

A notable feature of StealthScape is its cross-chain functionality, which allows it to be compatible with any EVM-compatible blockchain. This is achieved by deploying smart contracts on the target chain and setting up listeners to monitor specific events. The cross-chain compatibility is facilitated by a series of relayers that communicate between Layer 1 and Layer 2 networks, enabling seamless transaction execution across different blockchains. For wallet integration, we developed a custom Metamask SNAP, allowing users to interact directly with the Layer 2 solution, sign transactions, and manage their private keys securely. This approach allowed us to extend Metamask's capabilities without creating a custom wallet, reducing development time and leveraging a familiar user experience.

To handle a high volume of transactions, StealthScape uses Plasma, a framework designed for scalable and secure off-chain applications. Plasma allows transactions to be moved off the main Ethereum chain, significantly increasing throughput while reducing costs. We adopted a UTXO-based (Unspent Transaction Output) model, commonly used in privacy-centric cryptocurrencies, to further enhance the privacy of transactions processed on the Plasma chain. The Plasma framework was chosen because it allow us to handle a high volume of transactions off-chain, significantly increasing throughput while reducing costs and allow us to be a kind of blockchain on top of multiple blockchain to aggregate the liquidity.

One of the more innovative aspects of the project was our adaptation of existing tools and libraries for non-standard use cases. For example, we repurposed LMDB, which is typically used for low-latency data storage, to serve as the core storage layer for managing confidential transaction data. Similarly, we utilized RiscZER0 to generate ZK proofs specifically tailored to the UTXO model, which is an uncommon use case for this library. This creative use of existing technologies allowed us to achieve our goals more efficiently.

In the current development phase, we opted to operate the network in Proof of Authority (PoA) mode to simplify network management and accelerate development. PoA mode simplifies the operation by having a single authority manage the blockchain state, which avoids the complexities of a full proof-of-stake or proof-of-work model while testing and refining the system's core functionalities. The original idea was to use a staking mechanism to secure the network and improve decentralization.

Overall, StealthScape combines a range of advanced technologies and creative uses of existing tools to provide a scalable, private, and compliant solution for blockchain transactions. While there are areas for future improvement and optimization, this architecture lays a solid foundation for ongoing development and potential applications in various industries.