Very simple frequency domain(FFT based) image steganography/waterprint/signature.
Reference: https://www.zhihu.com/question/50735753/answer/122593277
Support index shuffle with secret in image mode and text mode:
usage: FdSig.py [-h] [-o OUTPUT] [-s SECRET] [-i IMAGESIGN] [-t TEXTSIGN] [-a ALPHA] [-d DECODE] [-v] file
positional arguments: file Original image filename.
optional arguments: -h, --help show this help message and exit -o OUTPUT, --output OUTPUT Output filename. -s SECRET, --secret SECRET Secret to generate index mapping. -i IMAGESIGN, --image IMAGESIGN Signature image filename. -t TEXTSIGN, --text TEXTSIGN Signature text. -a ALPHA, --alpha ALPHA Signature blending weight. -d DECODE, --decode DECODE Image filename to be decoded. -v Display image.