Editing Common Scrambling Algorithm (section)

===Fault attack===
In 2004, a fault attack<ref>{{cite journal
 | first = Kai | last = Wirt
 | title = Fault attack on the DVB Common Scrambling Algorithm (Report 2004/289)
 |date=November 2003
 | journal = Cryptology ePrint Archive
 | url = http://eprint.iacr.org/2004/289/
}}</ref> was published on the block cipher. The basic idea was to introduce a few deliberate faults in the intermediate calculations, making it possible to deduce the last eight round keys. From this, the final key can be computed.

While very few faults are needed (on average two or three per round key recovered), fault attacks are usually impractical to carry out, in that it requires the ability to change bits at will inside the hardware of a decoder that already has the key in question.