Conditional Access Module

A Conditional Access Module (CAM) [ kəndɪʃənəl æksɛs mɒdju ː l] ( German conditional access module ) is an electronic device that is inserted through a Common Interface slot in a DVB receiver. The task of this module is simply to manage the key exchange between smart card and the actual hardware decoder which operates on the Common Scrambling Algorithm ( CSA ). The CSA is used to decode programs from pay-TV providers. To this end, a key can be used, which is located on a smart card, the user will be given of his program against a single provider and / or monthly fee. This smart card to be introduced for this purpose in the CAM, so the computer located on the CAM can access the smart card.

Decryption

The actual decryption performs neither the smart card, nor the CAM, but both components are only used to reply to a sent request with a suitable key for decoding counter key. The actual decryption does not assume the CAM, but the receiver (or the CSA hardware ) itself

If one forms CSA and CAM software after it is possible, for example, simple smart card readers that are actually meant for reading by phone or debit card serial to connect for example to a PC and the smart card insert there.

However, appropriate software, such as scam is in a legal gray area, as you indeed can not see without a subscription pay- TV with her, but given the simple few protocol definitions limited " inventiveness " of the implemented in the CAM key request / response function would handle very high license fees of typically 80 to 250 euro ( = cost of a CAM). The pure production costs are well below 10 € (1 microcontroller ( max. 1 Euro ), board contacts and a simple plastic housing).

So the really expensive part lies long in the receiver, a CAM is only for licensing reasons so expensive. To avoid these costs, have / had several manufacturers, such as Dream Multimedia, planned their own " encryption scheme" to define (correct key exchange system ). From the hardware of the Dreambox can be the CAM part perfectly legal - if a private key exchange protocol is defined - implement purely in software. (And, ultimately, a CAM always contains software that surrounding hardware is finally only a microcontroller, electrical connections and a chassis).