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Figure 1
The proposed compression–encryption model.
Figure 2
Symmetric Key Generation Algorithm.
Figure 3
DWT decomposition 2D (a) one level (b) two levels.
Figure 4
Formation of matrix B from the result of LL sub-band element scrambling using ACM method.
Figure 5
Formation of symmetric keys K1, K2, K3, and K4.
Figure 6
(a) Initial cipher block of size 5×5, (b) session key KG3 which is formed using the proposed algorithm.
Figure 7
Example of key session KG4 which is randomly generated from the value of symmetric key K4 using the proposed algorithm.
Figure 8
Detailed proposed image compression–encryption model on the sender side.
Figure 9
Illustration of quantization result in binary form The bits are then grouped into 8 bit sized blocks, which produces 71 179 1 (in decimal), as shown in Figure 10.
Figure 10
Illustrated by data coding results.
Figure 11
The process of resizing the encrypted LL, LH, HL, and HH sub-bands data from the column vector to a matrix of size m × n 4) Divide the matrix produced in Step 4 into b × k blocks to do the process of block permutation cipher using session key KG3. The goal is to randomize the element.
Figure 12
Detailed propoed image decryption–reconstruction model on the receiver side.
Figure 13
Symmetric key values of Lena images with different intensities. (a) Without using the proposed algorithm and (b) using the proposed algorithm.
Figure 14
Symmetric keys generated in 30 experiments using Artichare, Pool, Lena, and Boat images.
Figure 15
Result of visual analysis to cipher image.
Figure 16
Average value of (a) NPCR, (b) UACI using the four testing images.
Figure 17
The average value of entropy from four testing images.
Figure 18
Average value of (a) PSNR, (b) compression ratio of the four testing images.
Result of Run-Test test to evaluate the randomness of the symmetric keys.
Test Image Data
Symmetric Key
P-Value
Conclusion
Test Image Data
Symmetric Key
P-Value
Conclusion
Artichare
K1
0.930
Random
Lena
K1
0.168
Random
K2
0.154
Random
K2
1.000
Random
K3
0.930
Random
K3
0.670
Random
K4
1.000
Random
K4
0.624
Random
Pool
K1
0.145
Random
Boat
K1
0.727
Random
K2
1.000
Random
K2
0.593
Random
K3
0.565
Random
K3
0.353
Random
K4
0.234
Random
K4
0.098
Random
Comparison of PSNR and CR values between images produced using the proposed and image produced by Hamdi et al. (2017), and Kumar and Vaish (2017).
PSNR
CR
Citra
Size
Classification
Proposed
Ref (Hamdi et al., 2017)
Ref (Kumar and Vaish, 2017)
Proposed
Ref (Kumar and Vaish, 2017)
peppers
512×512
High contrast
34.3206
32.6900
37.3047
30.0400
boat
512×512
High contrast
34.3238
31.0300
37.3047
30.3200
baboon
512×512
Moderate contrast
35.0083
24.8000
37.3047
31.7100
Lena
512×512
Moderate contrast
35.7503
33.2700
37.3047
29.9500
barbara
512×512
Moderate contrast
35.0709
26.2600
37.3047
31.3400
Average
35.7752
29.6100
37.3047
30.6720
house
512×512
Moderate contrast
37.6866
39.674
airplane
256×256
Bright image
36.3147
38.013
Average
37.0007
38.8435
Comparison of NPCR and UACI values between the proposed method and the method in Belazi et al. (2017), Hamdi et al. (2017), and Zhang and Tong (2017).
NPCR
UACI
Citra
Size
Classification
Proposed
Ref (Hamdi et al., 2017)
Ref (Belazi et al., 2017)
Ref (Zhang and Tong, 2017)
Proposed
Ref (Hamdi et al., 2017)
Ref (Belazi et al., 2017)
Ref (Zhang and Tong, 2017)
peppers
512×512
High contrast
99.7391
99.9676
-
99.6100
34.3270
33.3208
-
33.4700
Lena
512×512
Moderate contrast
99.7482
99.9150
-
99.5900
34.7650
33.5107
-
33.4200
barbara
512×512
Moderate contrast
99.7604
99.3656
-
99.5700
32.6374
33.4989
-
33.2900
Average
99.7492
99.7494
-
99.5900
33.9098
33.4435
-
33.3933
Lena
256×256
Moderate contrast
99.7360
99.8817
99.5895
-
34.7258
33.6860
33.4646
-
house
256×256
Moderate contrast
99.7742
98.9948
99.6353
-
35.5474
33.9622
33.4534
-
airplane
256×256
Bright image
99.7833
99.6680
99.5989
-
46.2548
33.2705
33.4396
-
Average
99.7645
99.5148
99.6079
-
38.8427
33.6396
33.4525
-
Comparison of entropy value between our proposed model with Belazi et al. (2017) and Zhang and Tong (2017).
Entropy
Citra
Size
Classification
Proposed
Ref (Belazi et al., 2017)
Ref (Zhang and Tong, 2017)
Airplane
512×512
Bright image
7.9988
7.9024
7.9931
house
512×512
Moderate contrast
7.9990
7.9027
7.9931
Lena
512×512
Moderate contrast
7.9989
7.9030
7.9929
barbara
512×512
Moderate contrast
7.9989
7.9025
7.9917
Average
7.9989
7.90265
7.9927
The average of PSNR, UACI, entropy, CR, PSNR values and encryption and decryption process times using 30 different keys.