To Air (FTA) receivers have been set up, giving up-to-date information on satellite and cable piracy, including making available firmware downloads for receivers, and very detailed encryption system information available to the public. Upon gaining the knowledge that their system has been compromised, the smart card providers often have several counter measure systems against unauthorised viewing, which can be put in place over the air, in most cases causing virtually no disruption to legitimate viewers. One such measure is CI revocation. The simplest form of counter measure is a key change. This simply halts viewing for those viewing without authorisation temporarily, since the new key can easily be accessed in the hacked card, and implemented. There are often other more complicated procedures which update a part of the smart card in order to make it inaccessible. These procedures can also, however, be hacked, once again allowing access. This leads to a game of "cat and mouse" between the smart card provider, and the hackers. This, after several stages of progression, can leave the smart card provider in a situation where they no longer have any further counter measures to implement. This leaves them in a situation where they must perform a card and encryption change with all legitimate viewers, in order to eliminate the viewing of the service without permission, at least for the foreseeable future. Such has been the success of implementing new smart card systems, that another form of smart card piracy has grown in popularity. This method is called card sharing, which works by making available the smart card decoding information in real time to other users, via a computer network. Police monitoring of unsecured card sharing networks has led to prosecutions. Virtually every common encryption system is publicly known to have been compromised. These include Viaccess, Nagravision, SECA Mediaguard and Conax. The MediaCipher system, owned by Motorola, along with Scientific Atlanta's PowerKEY system, are the only digital TV encryption systems which have not publicly been compromised. This is largely thanks to there being no PC card conditional-access modules (CAMs) available for either encryption system. Despite the unauthorised decryption of media being illegal in many countries, smart card piracy is a crime which is very rarely punished, due to it being virtually undetectable, particularly in the case of satellite viewing. Laws in many countries do not clearly specify whether the decryption of foreign media services is illegal