The card sharing writes "cardsharing" and also known as sharing control words, is to allow multiple users access to Pay TV channels from a single pass up sharing. The operation is made possible by sharing electronic decryption keys delivered by these smart cards, allowing all recipients simultaneous access to encrypted streams of TV packages.
In practice, a legitimate smart card administrator of a cardsharing network is connected to a television, or a computer equipped with software dedicated to sharing "control words" via the Internet. Once in possession of this key, the client can decrypt the encrypted content as if using his own subscriber card.