Confidential Transaction

Particle Network's Confidential zkStack enables users to transact privately by combining Stealth Accounts & Account Abstraction

The Confidential zkStack enables transactional privacy through confidential Paymasters that pay for transactions on behalf of users, as well as Stealth Smart Accounts to break onchain links.

Here's how Particle Network achieves this:

Transactional privacy mechanisms

Particle leverages ERC-4337 account abstraction to protect users’ privacy when transacting. The system uses a confidential Paymaster to send users’ transactions for them, breaking public on-chain links. Particle also uses a Stealth Smart Account mechanism to keep the receiver private.

Additionally, Particle also implements Guardian accounts and self-controlled social recovery.

Particle’s v2 private transaction system is diagrammed below:

Confidential Transaction heavily relies on Vitalik Buterin's proposed Stealth Account design. Within it, this account acts as the Owner of a smart account.

The process can be exemplified as follows:

1. Dynamic stealth address calculation: At the initiation of a transaction, Alice, the sender, dynamically calculates Bob's stealth address by utilizing Bob's meta-stealth data. This calculation is a pivotal step in ensuring the privacy and security of the subsequent transaction.
2. Smart stealth address computation: Building upon the dynamically calculated stealth address, Alice further computes what is referred to as the Stealth Smart Account. This specialized address serves as the destination for the asset transfer, introducing an additional layer of privacy and complexity to the transaction.
3. Secure stealth address retrieval: On the receiving end, Bob systematically scans for his stealth address within the incoming transaction data. Once located, Bob generates a spending key, providing him with the means to access and manage the received assets securely.
4. Confidential gas fee deposit: To facilitate the transaction and cover its associated gas fees, Bob employs any address to deposit the requisite gas fee into the Confidential Paymaster. This confidential deposit ensures the integrity and privacy of the transaction.
5. Flexible transaction signing: Armed with the spending key, Bob can now sign a signature for the UserOperation linked to the Stealth Smart Account for his convenience. The flexibility in timing adds an extra layer of security, allowing Bob to strategically execute the signing process.
6. Proof submission to Confidential Paymaster: Following the signing of the UserOperation, Bob submits the generated proof to the Confidential Paymaster. This proof acts as a confirmation, enabling the Paymaster to sponsor the necessary gas for the transaction. This final step ensures that the transaction proceeds seamlessly while maintaining the highest privacy standards.

In essence, this intricate and multifaceted process not only safeguards the privacy of individual transactions but also establishes a robust foundation for secure and confidential smart contract interactions. Particle Network's commitment to transactional privacy is exemplified through the seamless integration of ERC-4337 AA, stealth addresses, and Confidential Paymaster.