Certify an app using Unity

To make a signed build

1. Go to Edit -> Project Settings -> Player
2. Open the Publishing Settings tab

If you already have a keystore:

1. Tick "Use Existing Keystore" and then click "Browse keystore" to fetch it.
2. You have to provide the keystore password to allow Unity to read the key aliases.
3. Pick the correct alias and provide its password as well

4. You're done!

If you don't have a key already

1. Tick "Create new keystore..." and then click "Browse Keystore"
2. Now pick the path where the key will be created
3. Now pick a password and write it again to confirm
4. Click the alias dropdown and then chose "Create a new key"

5. Fill in all the details and click "Create Key"

6. Now go back to the alias dropdown and pick the alias you just created
7. You're done!