# CrossCurve Token Bridge

The **CrossCurve Token Bridge** lets projects present their token on other networks by locking their assets in smart contracts and issuing the token’s derivative on other networks. Our bridge allows you to move issued derivatives between blockchains in all directions, without having to return to the original token lock network using **Cross-chain Data Protocol** **(CDP)**.

Regardless of the differences among protocols, rules specifications and governance mechanics of these networks, a usage of the **CrossCurve Token Bridge** makes it possible for users to move assets among these chains in a reliable and secure way.

## Mechanics

The **CrossCurve Token Bridge** consists of the **Portal** and **Synthesis** smart contracts deployed in each of the Blockchains: 1, 2, 3, and uses the **CrossCurve Cross-chain Data Protocol (CDP)** to transfer cross-chain calls between them.

To move assets across Blockchains, the **CrossCurve Token Bridge** uses **synthetic assets (s-tokens)**. S-tokens are created when someone needs to transfer an asset between two blockchains.

### Example: Native Token Bridging

<figure><picture><source srcset="/files/Z2Ci6J3e6qSSdYNiNLaY" media="(prefers-color-scheme: dark)"><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXeRUWttkdRZi8BvJ7VaIBiwAjSUg3J_5_IQlbTQXkObRWrp6DJFmNtWwerBPdrohxxnm6zT9Nj0Yt_sg8ywYAYNox0s1kNlkmPRvCRq3g_Bm2By8eFMV5VAw6QHFRCeDhat9xsScw?key=blmc4LfhoPP44Q748Sjj_A" alt=""></picture><figcaption><p>Example of bridge with native tokens</p></figcaption></figure>

When transferring token **X**, the bridge uses a **Lock-Mint-Burn-Unlock** mechanism.\
The original **X token** is locked in the **Portal** smart contract on **Blockchain 1**.\
This transaction triggers an event in the bridge smart contract, which is monitored by the [**Consensus Bridge**](https://docs.crosscurve.fi/crosscurve-metalayer/what-is-crosscurve-metalayer/crosscurve-consensus-bridge).

The [**Consensus Bridge**](https://docs.crosscurve.fi/crosscurve-metalayer/what-is-crosscurve-metalayer/crosscurve-consensus-bridge) uses multiple messaging protocols to transmit the event to **Blockchain 2**.\
Once a sufficient number of confirmations are received from messaging protocols, the synthetic token **sX** is minted in the destination blockchain.

### Example: Synth Token Transfer Without Portal

<figure><picture><source srcset="/files/PaJRAHypoNEvwaCTWZKG" media="(prefers-color-scheme: dark)"><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXd2m_urqF8IYnL6Z7TziapVkIBtX79xYxYwwKl9f51py4STEDgMsYdONkQ1i9Paq-fJFX0_FQuGQQQM-mY-54LxAbAzKSZ6K7P27OKlsq8A_ektvpNp_jDu0Doy21hFArIltoPaKw?key=blmc4LfhoPP44Q748Sjj_A" alt=""></picture><figcaption><p>Example how bridge Synth tokens to other chain without use Portal</p></figcaption></figure>

When transferring a synthetic token **sX**, the bridge uses a **Mint-Burn** mechanism.\
The original **sX token** is sent to the **Synthesis** smart contract on **Blockchain 1**, triggering an event in the bridge contract.

The [**Consensus Bridge**](https://docs.crosscurve.fi/crosscurve-metalayer/what-is-crosscurve-metalayer/crosscurve-consensus-bridge) sends the message to **Blockchain 2** through multiple messaging protocols.\
Once enough confirmations are gathered, a **new instance of the same sX token** is minted on **Blockchain 2**.

{% hint style="info" %}

## Example in Practice

Let’s consider Bob transferring **X token** from **Blockchain 1** to **Blockchain 2**. The process works as follows:

1. Bob sends a transaction to the **CrossCurve Token Bridge**.
2. The original **X token** is locked in the **Portal** smart contract on Blockchain 1.
3. This triggers an event in the bridge contract, which is tracked and processed by the **Consensus Bridge**.
4. The Consensus Bridge uses multiple messaging protocols to independently relay the event to Blockchain 2.
5. Once enough confirmations are collected, the **sX token** is minted in Blockchain 2.

In our example, Bob’s transaction activates the **Synthesis** contract in Blockchain 2, which issues the synthetic **sX token**, backed by the **X token locked in Blockchain 1**.

At any time, Bob can initiate a reverse conversion to retrieve the original **X token**.
{% endhint %}

## Transaction history

Transferring tokens from one blockchain to another using the **CrossCurve Token Bridge** is a complex cross-chain operation. The user can track its execution in the interface in real time.

## Security

Only tokens whose smart contracts have been thoroughly audited by the **CrossCurve** team are added to the **CrossCurve Token Bridge**. The audit takes into account many characteristics of the project, and also examines the code of smart contracts for the presence of logic for moving and locking user tokens, which potentially creates a danger to user funds. Only tokens whose code complies with all security rules are allowed to be moved.\ <br>


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