A CI slot, or common interface slot, is used by digital television devices as a "middle man". The CI slot helps several components determine how to unscramble paid channels.
CI+, or common interface plus, is a 2008 drafted standard based on previous common interface guidelines. This new standard was created to increase copy protection. Many manufacturers now support this standard, including Panasonic, Philips, Samsung and Sony. This new mechanism now uses the same certificate and certificate authority system used by many online banks and retailers. This allows several different levels of encryption to occur, specific to the desires of the certificate issuer.