Viaccess it is system of coding for the digital television, developed France Telecom. On the beginning 2008 exists five modifications of this system of coding, Viaccess PC2.3, Viaccess PC2.4, Viaccess PC2.5, Viaccess PC2.6 and Viaccess PC3.0.
The first variant is named sometimes Viaccess 1, and by second three (though they and different), Viaccess 2. PC2.3 and PC2.4, as is known, are ineffective, and many receivers have today built in emulator Viaccess allowing to decrypt channels without payment, however PC2.5 and PC2. 6 while it is unavailable to pirates. Viaccess PC2.5 it has been entered in 2002, PC2.6 in the end of 2005 and PC3.0 has been presented on the middle 2007. Viaccess it is the variant of system of coding of analogue television EuroCrypt finished with reference to a digital television.
Exist as two modifications Viaccess PC2.3. The first, known as TPS Crypt, is used by French satellite TPS operator. After breaking the algorithm of enciphering TPS Crypt has been changed on system Advanced Encryption System usage (AES). Originally AES keys were refreshed once a day, second modification TPS Crypt in which keys vary each 12 minutes and these keys however has soon been entered are transferred on an internal open television network. Thus, only TPS receivers can receive new AES key. However soon monitoring and analysis AES of keys there were lists AES of keys where they were successfully predicted for some days forwards. Realisation of this procedure of an auto update of keys has appeared difficult, but possible. Periodically spending changes of keys do for some time piracy review impossible, however not for a long time and after upgrade of emulators TPS it is again possible to look.