# Deploying a smart contract

Deploying a contract is done as follows:

## Verifying the compiled binary in your workspace <a href="#verifying-the-compiled-directory-in-your-workspace" id="verifying-the-compiled-directory-in-your-workspace"></a>

This simply means verifying that the binary file you have compiled with static linking in the step which is [specific for your language](https://learn.qanplatform.com/developers/qvm-multi-language-smart-contracts/docs-for-supported-languages) exists in your current workspace folder. After you have successfully executed the compilation, the resulting binary should be in your workspace already under the name `contract`. To verify just execute this command:

```
ls -al contract
```

If everything went well you should see similar output:

`-rwxr-xr-x 1 user group 1204224 Jul 25 02:14 contract`

## Run the deploy command of `qvmctl` using docker <a href="#run-the-deploy-command-of-qvmctl-using-docker" id="run-the-deploy-command-of-qvmctl-using-docker"></a>

```
docker run --rm -v $(pwd):/ws qanplatform/qvmctl deploy --privkey privkey.txt contract
```

## What happens under the hood? <a href="#what-happens-under-the-hood" id="what-happens-under-the-hood"></a>

### Upload <a href="#upload" id="upload"></a>

* Deployment fees are estimated based on your contract size
* Balance check is performed whether your wallet address has enough funds to cover the fee
* Your contract binary is pinned to IPFS
* A checksum of the binary's integrity is generated
* The above checksum is signed with your private key
* A call is made to the QVM Repository contract with your IPFS CID + the signature
* Fees are either paid during this call or the whole call fails

### Download <a href="#download" id="download"></a>

* The QVM Repository contract emits a Deployment event upon successful deployment
* QVM Executor nodes will download the binary based on the IPFS CID
* They will cryptographically prove to the QVM Repository that the contract has been downloaded indeed
* The QVM Repository contract verifies the submitted cryptographic proof to ensure Executors have the binary
* If above verification verification was successful then the contract is Registered and is now callable