# Bridge Protocol

The Bridge Protocol facilitates the conversion between Wrapped ZCN (WZCN), an ERC-20 token on Ethereum, and Züs Coin (ZCN), the native token of the Züs blockchain. 

This process ensures a seamless and trustless transfer of assets between two blockchain ecosystems using a burn-and-mint mechanism, with verification and authorization handled by the Authorizer node.

The protocol ensures security through asymmetric key encryption, smart contract validation, and a structured reward-and-penalty mechanism for Authorizers.

### **Key Processes in the Bridge Protocol**

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#### **1. Signing Burn and Mint Tickets**

The Bridge Protocol operates based on burn and mint tickets, which serve as proofs of token conversion:

* **Burn Tickets (WZCN → ZCN)**
  * When a user wants to convert WZCN (Ethereum) to ZCN (Züs), they initiate a burn transaction on the Ethereum blockchain.
  * This generates a burn ticket, which is sent to an Authorizer node.
  * The Authorizer node verifies the transaction and signs the burn ticket.
* **Mint Tickets (ZCN → WZCN)**
  * When a user wants to convert ZCN (Züs) back to WZCN (Ethereum), they burn ZCN on the Züs blockchain.
  * This action generates a mint ticket, which must be signed by the Authorizer node before minting WZCN on Ethereum.

#### **2. Validation Process**

The **Authorizer node** plays a critical role in ensuring the validity of token conversions:

* **Burn Ticket Validation**
  * The Authorizer node verifies that WZCN tokens have been burned on Ethereum.
  * The node checks the Ethereum smart contract to confirm that the burn transaction is recorded.
  * Once validated, the Authorizer signs the burn ticket.
* **Mint Ticket Validation**
  * For mint tickets, the Authorizer node ensures that ZCN tokens have been burned on the Züs blockchain.
  * The node verifies the burn event in the Züs smart contract.
  * If verified, the Authorizer signs the mint ticket, allowing the minting of new WZCN on Ethereum.

#### **3. Asymmetric Key Encryption & Ticket Signing**

* The Authorizer node signs burn and mint tickets using asymmetric key encryption.
* Each signed ticket includes:
  * Burn/Mint transaction details.
  * Authorizer's digital signature (using its private key).
* Smart contracts on Ethereum and Züs can verify the validity of the signed ticket using the Authorizer’s public key.

#### **4. Integration with Smart Contracts**

The Bridge Protocol relies on smart contracts for enforcement and tracking:

* **Ethereum Smart Contracts**
  * Store burn events of WZCN.
  * Validate signed tickets before minting WZCN.
* **Züs Smart Contracts**
  * Track burn events of ZCN.
  * Verify mint ticket signatures before minting ZCN.

This ensures that every cross-chain transaction is properly recorded and authorized.

#### **5. Reward and Penalty Mechanism**

To maintain security and incentivize correctness, the Bridge Protocol implements a **reward-and-penalty** system:

**Rewards**

* Authorizer nodes earn rewards for validating and signing tickets.
* Rewards are distributed based on:
  * The number of burn tickets signed (for WZCN → ZCN).
  * The number of mint tickets signed (for ZCN → WZCN).
* **Rewards are paid in:**
  * ZCN for ZCN mint transactions.
  * ETH for WZCN mint transactions.

**Penalties**

* If an Authorizer node fails to properly validate a ticket, they may face penalties.
* Penalties include:
  * Loss of staking rewards.
  * Suspension from the Authorizer network for repeated failures.
* This ensures that malicious or careless behavior is discouraged, keeping the protocol secure.