GHIFARI, Moch Azhar Al and Surarso, Bayu and Sugiharto, Aris (2026) EVALUASI PROSES KRIPTOGRAFI CITRA MENGGUNAKAN ALGORITMA MODIFIED ARNOLD’S CAT MAP DAN MODIFIED HENON MAP. Masters thesis, UNIVERSITAS DIPONEGORO.

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Abstract

Keamanan data gambar digital merupakan aspek penting di berbagai bidang, seperti komunikasi, kedokteran, dan militer. Karakteristik bawaan gambar digital—yaitu korelasi piksel yang tinggi dan ukuran data yang besar—membuat metode enkripsi konvensional kurang optimal. Studi ini bertujuan untuk mengevaluasi kualitas enkripsi gambar menggunakan algoritma Modified Arnold’s Cat Map (ACM) dan Modified Henon Map, baik secara individual maupun kombinasi (ACM-Henon dan Henon-ACM). Modified ACM digunakan untuk mengatur ulang posisi piksel untuk menciptakan efek kebingungan, sedangkan Modified Henon Map digunakan untuk mengubah nilai piksel secara acak (difusi). Implementasi dilakukan menggunakan bahasa pemrograman Python dalam lingkungan pengembangan Visual Studio Code. Kualitas enkripsi dinilai menggunakan parameter seperti Avalanche Effect (AE), Unified Average Changing Intensity (UACI), Number of Pixels Change Rate (NPCR), Peak Signal to Noise Ratio (PSNR) dan koefisien korelasi. Hasil eksperimen menunjukkan bahwa metode berbasis chaos gabungan secara signifikan meningkatkan keamanan dibandingkan dengan algoritma individual, khususnya dengan menganalisis dampak urutan algoritma pada kualitas enkripsi. Kinerja terbaik dicapai oleh kombinasi Henon→ACM, menghasilkan NPCR ≈ 99,38%, UACI ≈ 19,03%, entropi ≈ 7,0315, AE ≈ 49,80%, dan PSNR ≈ 5,64 dB, menunjukkan keacakan yang kuat dan ketahanan terhadap serangan diferensial. Penelitian ini menunjukkan bahwa menggabungkan mekanisme kebingungan dan difusi menghasilkan citra sandi yang lebih aman daripada menggunakan salah satu metode saja. Kontribusi utama dari penelitian ini terletak pada penyediaan evaluasi komparatif sistematis dari skema enkripsi berbasis chaos tunggal dan gabungan, termasuk analisis sensitif urutan di berbagai karakteristik citra, daripada mengusulkan algoritma enkripsi baru. Namun, kinerja enkripsi dipengaruhi oleh ukuran gambar, pemilihan parameter, dan jumlah iterasi, yang dapat membatasi konsistensi di berbagai karakteristik gambar.
Kata kunci: Modified Arnold’s Cat Map, Modified Henon Map, enkripsi citra, chaotic system, validasi keamanan

The security of digital image data is a crucial aspect in various fields, such as communications, medicine, and the military. The inherent characteristics of digital images—namely high pixel correlation and large data size—render conventional encryption methods less optimal. This study aims to evaluate the encryption quality of images using the Modified Arnold’s Cat Map (ACM) and Modified Henon Map algorithms, both individually and in combination (ACM-Henon and Henon-ACM). Modified ACM is utilized to rearrange pixel positions to create a confusion effect, while the Modified Henon Map is employed to randomly alter pixel values (diffusion). The implementation is carried out using the Python programming language within the Visual Studio Code development environment. Encryption quality is assessed using parameters such as Avalanche Effect (AE), Unified Average Changing Intensity (UACI), Number of Pixels Change Rate (NPCR), Peak Signal to Noise Ratio (PSNR), and correlation coefficient. Experimental results show that the combined chaos-based methods significantly enhance security compared to the individual algorithms, particularly by analyzing the impact of algorithm order on encryption quality. The best performance was achieved by the Henon→ACM combination, producing NPCR ≈ 99,38%, UACI ≈ 19,03%, entropi ≈ 7,0315, AE ≈ 49,80%, and PSNR ≈ 5,64 dB, indicating strong randomness and resistance to differential attacks. This research demonstrates that combining confusion and diffusion mechanisms yields more secure cipher images than using either method alone. The main contribution of this study lies in providing a systematic comparative evaluation of single and combined chaos-based encryption schemes, including order-sensitive analysis across different image characteristics, rather than proposing a new encryption algorithm. However, the encryption performance is influenced by image size, parameter selection, and iteration count, which may limit consistency across different image characteristics.
Keywords: Modified Arnold’s Cat Map, Modified Henon Map, image encryption, chaotic systems, security validation

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