A Multimode Network Steganography for Covert Wireless Communication Based on BitTorrent

Table 4

Definitions of the statistical features.

Input variable	Feature	Formula	Explanation
x1	Mean		li is the length of <bitfield>; n is the subsample size
x2	Median		Where the lengths are sorted in ascending order
x3	Entropy		p(li) is the probability of length li
x4	Standard deviation		li is the length of <bitfield>; μ is the mean of the lengths
x5	Root of average mean error		li is the length of <bitfield>; μ is the mean of the lengths