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. 2025 Aug 30;15(1):31986.
doi: 10.1038/s41598-025-13290-y.

A lightweight multi round confusion-diffusion cryptosystem for securing images using a modified 5D chaotic system

T Anujaa  1 , Afra Fathima Thajudeen Ali Ahamed  1 , Vedika Baranwal  1 , V Thanikaiselvan  1 , S Subashanthini  2 , C Sivaranjani Devi  3 , Amirtharajan Rengarajan  3
Affiliations

A lightweight multi round confusion-diffusion cryptosystem for securing images using a modified 5D chaotic system

T Anujaa et al. Sci Rep. .

Abstract

In recent years, technological advancements have made the transmission of confidential information spooky. This research proposes a modified 5D chaotic map and a new image encryption algorithm based on an integrated chaotic system developed with SHA-512 hashing and a confusion-diffusion architecture. The modified 5D chaotic map provides randomness, and its performance is evaluated through a bifurcation diagram and Lyapunov exponent. The randomness of chaotic sequences is validated through the NIST test. The multi-round diffusion and permutation incorporating the proposed chaotic sequences significantly enhances security by destroying pixel correlation among pixels. The encryption algorithm is validated through performance metric analysis, yielding NPCR of 99.6069%, UACI of 33.4284%, and entropy of 7.99442. These values depict advanced security features needed for various multimedia, medical, and military applications. Therefore, this approach reveals the extent to which chaotic encryption systems provide digital image protection in high-risk communication environments.

Keywords: Chaotic maps; Confusion-diffusion; Digital security; Image encryption; Multimedia protection; SHA-512.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests. Ethics approval: This article contains no studies with human participants performed by authors. Data availability: The datasets generated during and/or analysed during the current study are available from the corresponding author upon reasonable request. The sources of the sample images are downloaded from https://sipi.usc.edu/database/database.php?volume=aerials , https://www.kaggle.com/datasets/samahsadiq/benign-and-malicious-qr-codes , https://www.dicomlibrary.com/ , http://bias.csr.unibo.it/fvc2000/download.asp .

Figures

Fig. 1
Fig. 1
(a) Steps for proposed system confusion diffusion mechanism. (b) Flow diagram of the proposed methodology. (c) Encryption algorithm architecture.
Fig. 1
Fig. 1
(a) Steps for proposed system confusion diffusion mechanism. (b) Flow diagram of the proposed methodology. (c) Encryption algorithm architecture.
Fig. 2
Fig. 2
(a) Original image, (b)initial diffusion using S1, (c) row shuffling using S2, (d) xor-ing row shuffled matrix with S2, (e) column shuffling using S3, (f) xor-ing column shuffled matrix with S3, (g) final encrypted image using a secondary image.
Fig. 3
Fig. 3
Phase diagram of the chaotic system. (a) phase diagram of the d1-d2-d3 plane, (b) phase diagram of the d2-d3-d4 plane, (c) phase diagram of the d3-d4-d5 plane, (d) phase diagram of the d1-d3-d5 plane.
Fig. 4
Fig. 4
(a) Bifurcation diagram and (b) Lyapunov exponent.
Fig. 5
Fig. 5
(a) Original image, (b) Histogram of original image, (c) Encrypted image, (d) Histogram of encrypted image.
Fig. 5
Fig. 5
(a) Original image, (b) Histogram of original image, (c) Encrypted image, (d) Histogram of encrypted image.
Fig. 6
Fig. 6
Original image correlation analysis (a) Original image (b) Horizontal, (c) Vertical, (d) Diagonal.
Fig. 6
Fig. 6
Original image correlation analysis (a) Original image (b) Horizontal, (c) Vertical, (d) Diagonal.
Fig. 7
Fig. 7
Encrypted image correlation analysis (a) Encrypted image (b) Horizontal, (c) Vertical, (d) Diagonal.
Fig. 7
Fig. 7
Encrypted image correlation analysis (a) Encrypted image (b) Horizontal, (c) Vertical, (d) Diagonal.
Fig. 8
Fig. 8
Entropy values of (a) Global, (b) Local.
Fig. 9
Fig. 9
Chi square analysis of (a) Original image, (b) Encrypted image.
Fig. 10
Fig. 10
(a) NPCR, (b) UACI analysis of 100 samples.
Fig. 11
Fig. 11
(a) Original image, (b) Encrypted image using original key, (c) Encrypted image using varied key, (d) Difference between b and c.
Fig. 12
Fig. 12
(a) MSE and (b) PSNR analysis of 100 samples.
Fig. 13
Fig. 13
Maximum deviation.
Fig. 14
Fig. 14
Deviation from ideality.
Fig. 15
Fig. 15
Irregular deviation.
Fig. 16
Fig. 16
Cropping attack analysis (a)encrypted image cropped with 10%, (b) decrypted image of a, (c)encrypted image cropped with 25%, (d) decrypted image of c, (e)encrypted image cropped with 50%, (f) decrypted image of e.
Fig. 17
Fig. 17
Noise attack analysis (a) encrypted image added with salt and pepper noise, (b) decrypted image of a, (c) encrypted image added with Gaussian noise, (d) decrypted image of c, (e) encrypted image added with speckle noise, (f) decrypted image of e.
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