# 10.7 zk-Bridge

BitNet’s zk-Bridge architecture adds a **privacy-preserving layer** to cross-chain bridges by integrating **zk-SNARKs**. Users can transfer assets without revealing their source, destination, or wallet address.

**How It Works**

**1. Deposit**

* Assets are deposited into a bridge smart contract.
* A commitment hash is generated and stored: `commitment = Hash(secret, recipient, amount)`

**2. zk-SNARK Proof Generation**

* Off-chain, users generate a proof showing ownership of a valid unspent deposit.
* The proof hides identity, source chain, and amount.

**3. Withdrawal**

* The user submits a zk-proof and nullifier (prevents double-spending).
* The contract verifies the proof and releases the funds anonymously.

**Architecture**

* Acts as **middleware**, not a full bridge replacement.
* Compatible with EVM chains using Solidity and Circom-based verifiers.
* Supports modular integration into existing bridge UI/UX.

**Benefits**

* **Unlinkable Transfers**: Breaks connection between deposit and withdrawal events.
* **DeFi Composability**: Can be used with private DEXes, lending protocols, and DAOs.
* **Anonymity Set**: Mimics privacy features of full ZK systems like Tornado Cash.

**Implementation Challenges**

* zk-proof generation is still compute-intensive.
* Requires robust, decentralized relayer networks.
* Complex UX (managing secrets, nullifiers) must be abstracted for users.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://bitnet-whitepaper.gitbook.io/bitnet-whitepaper/10.-ecosystem/10.7-zk-bridge.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.