The control word is generated automatically in such a way that successive values are not usually predictable; the DVB specification recommends using a physical process for that.
This allows the use of several conditional access systems at the same time, a DVB feature called simulcrypt, which saves bandwidth and encourages multiplex operators to cooperate.
Several companies provide competing CA systems; ABV, VideoGuard, Irdeto, Nagravision, Conax, Viaccess, Synamedia, Mediaguard (a.k.a.
A large proportion of the systems currently in use for DVB encryption have been opened to full decryption at some point, including Nagravision, Conax, Viaccess, Mediaguard (v1) as well as the first version of VideoGuard.
In Canada and United States, the standard for conditional access is provided with CableCARDs whose specification was developed by the cable company consortium CableLabs.
Next-generation approaches in the United States eschew such physical cards and employ schemes using downloadable software for conditional access such as DCAS.
The main appeal of such approaches is that the access control may be upgraded dynamically in response to security breaches without requiring expensive exchanges of physical conditional-access modules.
2018 Despite the Programming Center shut down its consumer usage of DigiCipher 2 (as 4DTV) on August 24, 2016, it is still being used for cable headends across the United States, as well as on Shaw Direct in Canada.