Scrambling and descrambling of data with improved security

摘要

A scrambling method of a stream formed of a series of unit streams in succession, the unit stream including a first stream part and a second stream part located behind the first stream part. The scrambling method scrambles the second stream part by using a random number generator and includes a step of supplying predetermined data included in the first stream part and having a non-fixed value, for each of the second stream part to be scrambled, to the random number generator as an initial value. Further, a scrambling apparatus, a descrambling method and a descrambling apparatus are disclosed.