If you participated in Curio Cards back in 2017 your card wallet might be saved in a Keystore file. You can still access your Cards, but this is now an outdated method for storing Ethereum wallets. It is recommended that you migrate to a newer method. Newer methods (like MetaMask) will also allow you to Wrap/Unwrap, Trade, and Vote with your cards a lot easier.
In the following steps, you could find yourself accessing passwords, seed phrases, and private keys. BE CAREFUL! Anyone with access to this private key or seed phrase can steal all your funds and cards. Curio Cards, MetaMask, MEW, etc, will NEVER email or message you requesting your private key or seed phrase FOR ANY REASON. There is no valid support reason for anyone to need to request this information. You are the only person who needs to control, backup, or access your wallet.
Note that if you have a file like the one above it will also require a password to access.
Pros: Safer (your Cards are backed up with your MetaMask Seed Phrase and your private key is never revealed)
Cons: Gas costs to transfer your Cards to the new address
Curio Cards ran a version of the original MyEtherWallet (MEW), called MyCurioWallet , that had support for the card addresses built-in. MyCurioWallet is still accessible if needed (covered in Method 2) but it is outdated and less secure. The new version of MEW still supports loading Keystore files and can display the Card balances. You can use it to transfer your Cards to a new wallet, but it does not support revealing the private keys for security reasons.
Go to https://MyEtherWallet.com/
Scroll down and select 'Access My Wallet'
Select your Keystore file and enter your password
You can now see your Cards in the Token List on the right side of the Dashboard
Select Send in the sidebar, choose your Cards, and send them to your MetaMask wallet. Make sure you have already backedup your MetaMask wallet!
Lastly, How to Display your Cards in MetaMask. This step is needed so you can see your card balances in the MetaMask wallet
Pros: No gas costs
Cons: Less safe (need to reveal and then back up your private key)
There are a few ways you can extract your Private Key from the Keystore file. None of the modern online wallets support this feature for various security reasons, but you can still access them using a few methods:
MyCrypto (a popular fork of MyEtherWallet) Desktop wallet:
The Desktop version of MyCrypto can be downloaded here: https://download.mycrypto.com/
Documentation for how to access a Keystores private key is located here:
This method is the most secure as the private keys are not revealed using an online webpage
The old MyCurioWallet
MyCurioWallet has so far been left only up for convenience and emergencies, but is no longer a fully functional wallet (the old nodes are no longer supported) and should not be considered a secure option (it is easier to perform phishing attacks with websites). Nevertheless, it does offer a quick way to view a keystore file's private key
Go to "View Wallet Info" in the header
Choose Keystore from the methods, select your file and enter your password
You will now have the ability to see your public key as well as reveal your private key
Downloading ad running an offline version of the old MyEtherWallet
Documentation for this method with trusted download links is harder to come by now given the age of the old version of MEW