Algoritma Enkripsi Selektif Citra Digital dalam Ranah Frekuensi Berbasis Permutasi Chaos

Abstract

This paper presents a selective image encryption in frequency domain. At first, the image is
transformed into frequency domain with Discrete Cosine Transform (DCT), and then DCT coefficients are
scanned in zigzag, and elements of the low-frequency sub-band are extracted. Encryption is performed only on
selected elements by scrambling them using 2D chaos map, namely Arnold Cat Map. Next, IDCT is applied to
obtain the encrypted image. The encryption algorithm is included in lossy encryption. Experiments on both
grayscale images and color images show that the images can be encrypted succesfully. Histograms of the encrypted
images differ significantly from histogram of the original images, and the pixels in the encrypted images are not
longer correlated.