# Symbiosis BridgeV2 Contract

{% hint style="info" %}

* If you are curious to see the Symbiosis Protocol in action, check out \
  [Symbiosis WebApp](https://app.symbiosis.finance/swap?chainIn=Ethereum\&tokenIn=ETH).
* The Symbiosis Core Smart Contracts are open source and available at\
  <https://github.com/symbiosis-finance/core-contracts>.
* For security audits, please refer to [Security Audits](/main-concepts/security-audits.md).
  {% endhint %}

In the previous article: [Symbiosis Mint-Burn Process](/crosschain-liquidity-engine/synthesizing-process.md), we explained the core concept of cross-chain operations:&#x20;

* When the **Portal** locks tokens on one blockchain, **Synthesis** mints tokens on another blockchain.
* When **Synthesis** burns tokens on one blockchain, the **Portal** releases tokens on the original blockchain.

Now let’s take a closer look at the `BridgeV2` contract.

An instance of the `BridgeV2` contract is deployed on each blockchain supported by Symbiosis. It acts as a proxy between the **Rrelayers Network** and the **Portal/Synthesis** contracts.

`BridgeV2` accepts calls from two sources:

1. **Portal/Synthesis contracts** deployed on the same blockchain\
   When invoked by these contracts, `BridgeV2` emits an **Oracle request** (i.e., a smart contract event) that contains all the necessary data and instructions to carry out the corresponding operation on the destination blockchain.
2. **Relayers Network**\
   These are off-chain entities submitting transactions signed with an MPC (multi-party computation) key. The corresponding MPC address is stored in the `BridgeV2` contract. When `BridgeV2` is called via such a transaction, it executes the instructions included in the transaction calldata on-chain.

**Scheme 1** below illustrates the `BridgeV2` workflow during cross-chain operations:

<figure><img src="/files/cVH8zA4ObJqa0QnuuTA6" alt=""><figcaption><p>Scheme 1. BridgeV2 routine.</p></figcaption></figure>

{% hint style="info" %}
**Relayers Network:** See [Relayers network](/relayers-network/symbiosis-relayers-network.md) for more details.
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