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Smart Contracts
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   :alt: Smart Contract Audit Badge
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**GITHUB LINK:** `CarbonPath Smart Contract <https://github.com/carbonpathio/carbonpath-smart-contract>`_

**SECURITY AUDIT:** `Hacken Smart Contract Review & Report <https://hacken.io/audits/carbonpath/>`_

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Contract Types
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1. **CarbonPathAdmin** 

  - a contract that handles different interactions with **CarbonPathToken (CPCO2)** and **CarbonPathNFT** and serves as an admin for both contracts. Users can buy CPC02 tokens and retire them for a certain well.

2. **CarbonPathNFT**

  - ERC721 token that bounds to a well. Contains the geolocation of a well and additional metadata.

3. **CarbonPathToken**
  
  - ERC20 mintable and burnable token that represents locked carbon emission.

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Priviledged Roles
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1. **Default Admin** 

  - CarbonPathAdmin: can grant and revoke minter role, set receiver of CP fee, non-profit address, buffer pool address, seller address.
  - CarbonPathToken: can grant and revoke minter role

2. **Minter**

  - CarbonPathAdmin: can mint new tokens, update token URI and metadata
  - CarbonPathToken: can mint, burn tokens

3. **Owner** (CarbonPathNFT Only)

  - CarbonPathNFT: can set admin address

4. **Admin** (CarbonPathNFT Only)

  - CarbonPathNFT: can set metadata and URI for a specific token, mint new tokens, and increase the amount of retired CPCO2 tokens

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Functions
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1. **Mint**
 
  - Mints a new well. This also attaches the geoJSON, metadata and well files to the minted well.
  - During minting, CPCO2 Tokens are airdropped to the following recipients:
      - **cpFeeAddress** will receive `advancedAmount * cpFeePercentage` of CPCO2 Tokens.
      - **operatorAddress** will receive `advancedAmount * (100% - cpFeePercentage)` of CPCO2 Tokens.
      - **bufferPoolAddress** will receive `bufferPoolAmount * 95%` of CPCO2 Tokens.
      - **nonProfitAddress** will receive `bufferPoolAmount * 5%` of CPCO2 Tokens.
  - **NOTE: CarbonPath may update the metadata and well files even after the well is minted**

2. **Buy**

  - Buy CPCO2 Tokens from the contract
  - Current Exchange Rate is `1 CPCO2 = 30 cUSD`

3. **Retire**

  - Retire a CPCO2 token permanently locking the CO2.
  - It will automatically update the retire info for the chosen well.


4. **Sell**

  - **NOTE: FOR CARBONPATH WALLETS ONLY**
  - Transfer CPCO2 tokens to the contract for selling. All tokens owned by the contract are considered sellable.

5. **Withdraw**

  - **NOTE: FOR CARBONPATH WALLETS ONLY**
  - Withdraw stored CPCO2 Tokens from the contract and remove them as sellable