> For the complete documentation index, see [llms.txt](https://docs.nullmask.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nullmask.pro/virtual-network.md).

# Virtual Network

### Concept <a href="#concept" id="concept"></a>

Nullmask introduces itself to the user's wallet as a **virtual private EVM network**. This is not a real blockchain — it is a mechanism that places a custom RPC proxy between the wallet and the actual blockchain node.

### How It Works <a href="#how-it-works" id="how-it-works"></a>

#### Adding the Network <a href="#adding-the-network" id="adding-the-network"></a>

During onboarding, the user's wallet is prompted to add a new network with:

* **Network Name**: Nullmask (or chain-specific name)
* **RPC URL**: The proxy server URL with an embedded access token
* **Chain ID**: A virtual chain ID (e.g., 43615 for Ethereum Mainnet)
* **Currency Symbol**: ETH (same as the underlying chain)

All these parameters are preconfigured by the app — the user only confirms a wallet dialog.

#### Transaction Interception <a href="#transaction-interception" id="transaction-interception"></a>

When the user sends a transaction on the Nullmask network:

1. The wallet constructs and signs a standard EIP-1559 transaction
2. The wallet sends `eth_sendTransaction` (or `eth_sendRawTransaction`) to the proxy
3. The proxy detects it as a value transfer and shields it:
   * Translates 0x address to shielded address
   * Generates a ZK proof
   * Submits via the relayer
4. The proxy returns a transaction status to the wallet

#### Balance Queries <a href="#balance-queries" id="balance-queries"></a>

When the wallet queries `eth_getBalance` or ERC-20 `balanceOf`:

1. The proxy intercepts the call
2. Instead of querying the blockchain, it returns the user's **shielded balance** from local note storage
3. The wallet displays the shielded balance as if it were a normal balance

#### Access Token <a href="#access-token" id="access-token"></a>

Unlike a traditional RPC node where all data is public, the Nullmask proxy must restrict data access. An access token is embedded in the RPC URL and stored as an HTTP-only cookie. This token:

* Derives from the user's ECDSA signature (deterministic)
* Isolates each user's private data (keys, notes, transactions)
* Persists across sessions via secure cookies

### Local vs Remote Deployment <a href="#local-vs-remote-deployment" id="local-vs-remote-deployment"></a>

The proxy can run in two modes:

#### Remote Server <a href="#remote-server" id="remote-server"></a>

* Accessed via a web page (the default deployment)
* Full on-chain privacy is maintained
* The server operator can observe user transfers
* No installation required

#### Local Device <a href="#local-device" id="local-device"></a>

* Runs on the user's mobile device or as a browser extension
* Full privacy — no third party sees transfers
* Requires installation


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