> For the complete documentation index, see [llms.txt](https://armonia-meta-chain-1.gitbook.io/amax-whitepaper/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://armonia-meta-chain-1.gitbook.io/amax-whitepaper/overall-architecture/2.60-cross-chain-mechanism.md).

# 2.60 Cross-Chain Mechanism

In Armonia's multichain universe, the ability of "moving" an asset from one chain to another can be critical for asset owners. If the originating asset resides in its home chain where the asset is issued from, "moving" the asset means locking an asset in the originating chain and minting the assets from the destination chain and transferring the assets to the designated account. However, if the originating asset resides in a non-native chain, "moving" the asset means destroying or burning the asset from the originating chain, unlocking the asset and sending the designated account from the home chain to the asset. This two-way moving activity that happens between any two chains within Armonia's multichain universe are cross-chain transactions.

Through cross-chain transactions, asset owner can move an asset from one chain to another, which greatly increases the liquidity and usability of the asset. This flexibility can help satisfy all kinds of application scenarios that happen in the entire ecosystem.

However, the following problems must be solved to achieve bi-directional, reliable and efficient cross-chain transactions:

* how to ensure the finality of the asset-moving transaction on-chain?
* how to synchronize the asset transferring or locking result from one chain to another?
* how to ensure transactions involved in cross-chain workflow are effective and accurate as expected?
* how to prevent malicious users from stealing the assets during the cross-chain transactions?
* how to prevent the mirroring asset from being overly inflated?

At the same time, one important question that remains to be answered is: How to establish a simple-to-use and unified cross-chain solution that can work with all kinds of blockchain in Armonia's multichain universe?

In addressing the above problems, one hybrid and reliable cross-chain solution has been proposed as follows:

**Legend**:

| Item                         | Symbol |
| ---------------------------- | ------ |
| Armonia Meta Chain           | `M`    |
| Asset originating chain      | `A`    |
| Asset destination chain      | `B`    |
| Cross-chain user             | `BU`   |
| Cross-chain operator         | `BO`   |
| Cross-chain asset            | `AS`   |
| DAO for asset-mirrored chain | `DAO`  |

Note: Distribution of assets from chain `A` has been determined by its consensus mechanism, tokenomics and ecosystem. However, for an asset to be mirrored to its destination chain `B` it must be managed within an `ERC20` token contract for its issuing, minting, transferring, burning, etc. and these activities will be governed by its `DAO` body.

* Preparation work

1. Deploy a smart contract `amax.xswap` onto chain `M` for cross-chain management;
2. Deploy a smart contract `as_custody` onto chain `A` to lock cross-chain assets; and
3. Deploy a smart contract `as_erc20` onto `B` for issuing, minting and destroying mirrored assets, governed by its DAO.

* Workflow

1. `BO` approaches `DAO`, requests bridging assets from `B`, say 1 mn `AS`, and sends them into `as_custody`. Then, `DAO` mints 1 mn AS from `as_erc20` and transfers them to `BO`;
2. `BO` places orders on `amax.xswap` with `$AMAX` as escrow that is locked into the same contract;
3. `BU` finds the orders they want to take from `amax.xswap` and they can either take the orders partially or entirely;
4. `BU` sends `AS` from chain `A` to `BO`'s account and posts its transaction ID to `amax.xswap` as payment proof; and
5. `BO` sends `AS` from chain `B` to `BU`'s account upon notification of order status change and closes the order upon `BU`'s confirmation;

Note:

1. When there's any dispute about swap orders, `DAO` will be involved to do the arbitrage to ensure the complete closure of the orders;
2. `AMC` can also be `A` or `B` chain.<br>

The detailed workflow diagram:

<figure><img src="/files/YfIoMcGDTNtE85pLSyLt" alt=""><figcaption></figcaption></figure>