Main features of Selective Encryption are the following
Time taken to encrypt the subset of data is lower as compared to whole data.
It encrypts only that subset of data that are very crucial as compared to whole data.
It conserves resources and power.
It is format compliant.
For encryption of data, it can use any encryption algorithm that user wants.
The cipher appears only as distorted image or video.
Compression is done on them to make it more distorted.
a) Classification of Selective Encryption
Selective Encryption Algorithms are classified based on following approaches [3]:
1) Precompression
In Precompression method, the compression is done after the encryption. They are inherently format compliant and irrelevant for lossy compression. But drawback of using this method is that it causes bandwidth expansion and adversely impact compression efficiency. Hence this method is not compression friendly