of subscribed receivers and or smartcards. The designers have the choice of using their own custom, secret algorithm or using a publicly tested one. The first approach is often referred to as security by obscurity. It can work well if the technology and the algorithm are robust. This approach also has a hidden catch for any potential pirate in that he would have to understand and emulate the custom algorithm in order to implement a pirate device. With many digital TV encryption systems relying on smartcards for their security, any compromise of the smartcard would require a complete replacement of all smartcards being used. That could potentially involve the replacement of millions of smartcards. On a system with a low number of subscribers, the smartcards can be replaced periodically. However, as the number of subscribers grows, the cost of replacing the smartcards and the logistics of the replacement encourages the system users to try to get the longest use out of the smartcards before replacement. The chances of a fatal compromise on the smartcard increases as the time between replacement increases. Any compromise of the smartcard or algorithm will become public quickly. Computers and Internet can be used to make crucial design details publicly available. Internet sites may be located offshore in countries where local laws permit the information and software to be distributed openly; some of the more notorious software distributed to pirates ranges from NagraEdit (a program intended to edit the information stored on Swiss-designed Kudelski NagraVision 1 smartcards) to firmware which may be used to reprogram some free-to-air set-top boxes or desktop PCs equipped with Digital Video Broadcasting (DVB) tuner cards to permit them to decode encrypted broadcasts. The secrecy of any algorithm is only as trustworthy as the people with access to the algorithm; if any of them were to divulge any of the design secrets, every card with the compromised algorithm may need to be replaced for security to be restored. In some cases, outside personnel (such as those employed by lawyers in the NDS vs. DirecTV intellectual property lawsuit over the P4 card design) may obtain access to key and very sensitive information, increasing the risk of the information being leaked for potential use by pirates. If less secure encryption is used due to processor limitations on the smartcards, the system is vulnerable to cryptographic attack using distributed processing. While most secure Internet and