Page 97 - 2024-Vol20-Issue2

93 | Shumran & Al-Hussein

Fig. 11. decryption scheme, adopted from [24].

S-box 165 165 S-box 1
165 165 S-box 2
165 165 S-box 3
165 165 S-box 4
S-box 5
S-box 6
S-box 7
S-box 8

132 132 17 245 Fig. 13. Proposed encryption scheme flow diagram, adapted
132 132 8 132 from [27].
132 132 90 128
132 132 165 165 data is put with each other to produce the encrypted signal.
The result shows that the key is 144-bit long, with the best
Fig. 12. Transformation effect through S-box, adapted scores of the residual intelligibility measure using correlation
from [25]. coefficients which is about (-0.0082).

to convert each sample to a number of bits. In the second In 2017, P. Sathiyamurthi et al [30], presented the four
method, the sample of the henon map is limited with a real chaotic maps used in the speech encryption system: the
value threshold then it is converted to binary sequence bits. quadratic map, the tent map, the logistic map, and Bernoulli’s
The last method is the comparator method which mainly de- map, which serves as a chaotic shift key technique. The origi-
pends on the comparison between the output of the two henon nal speech is separated into four levels, and the four attractors
maps in order to convert the real value to binary bits. produced by the chaotic maps are used to permute each level
of the speech.
In 2017, Ardalan Ghasemzadeh et al [29], introduced a
speech encryption system by using three chaotic methods In 2018, Wafaa S. Sayed et al [31], proposed a new speech
namely; the logistic map, the nonlinear chaotic algorithm map encryption by using the generalized modified transition map,
(NCA), and the tangent-delay ellipse reflecting cavity-map the main idea behind this map is the conjugacy between two
system (TD-ERCS). The encrypted process is done by multi- maps which are the tent and logistic map. The encrypted
plying the audio signal by a constant value, each part then is speech signal is generated by XORing the unsecured digital
converted to a binary form and divided into three chunks, also speech signal after passing through the bit permutation with
each part of the divided chunk is XORed with the generated the PRBG key. The findings indicate that the System’s key
value from one of the three chaotic methods. Finally, the space is 2128.