Why does Upham recommend storing the length of the hidden data in a variable length field?
Expert Answer
Upham was the first publicly available steganographic system for JPEG images.
Upham recommends storing the length of the hidden data in a variable length field.
Because the length of the hidden message can be variable number of bits.
So this is not easy to detect hidden data for the maximum file size.
Because bits depends on the length of the hidden data.