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Fig. 1. Scheme of audio encryption techniques.
niques used in encryption processes, where we classified the
methods into encryption based on traditional methods such as
(DES, AES, RSA) and encryption based on chaotic systems,
which are divided into two types: continuous-time systems
such as (Lorenz, Chen, Chua) and discrete time systems such
as (Henon, Arnold Catt map, logistic map). As well as clas-
sifications based on different implementation methods, such
as (FPGA, Raspberry Pi), types of synchronization systems,
chaotic systems based on fractional order systems, and hybrid
chaotic generator systems, as shown in Fig. 1.
A. Traditional Methods:
In 2012,by Rahman et al [10], the authors proposed an effec-
tive way to encrypt and decrypt speech data using the RSA
algorithm. The maximum number of characters that can be
encrypted at once is constrained by the requirement that the
integer representation of the message to be encrypted must lie encrypted using RSA and sent to a digital-to-analog converter
Shumran & Al-Hussein
within the range given by the modulus (i.e., M lies in the range
[0, n - 1]). With their continued efforts, all of this algorithm’s
drawbacks have been eliminated, and speech communication
systems will use the RSA digital signature scheme.
In 2016, Khalil [11], they proposed and evaluated two
distinct encryption/decryption algorithms that are applied to
the audio signal in real-time. The first is the conventional
RSA encryption and decryption method, and the second is
a newly proposed algorithm built on the idea of symmetric
cryptography. The suggested algorithms are simulated and
the real-time audio signal is obtained using the MATLAB
Simulink simulator tool. Given the mathematical nature of
the audio signal, the experimental results demonstrated that
the recommended algorithm produces an audio signal with
high quality that is identical to the original signal, while the
RSA method produces an audio signal with low quality.
In 2020, Sura F .Yousif [12], proposed sound signal en-
cryption and decryption using the RSA algorithm. The algo-
rithm’s performance was evaluated through an experimental
implementation. Using MATLAB simulations, the results
indicated that the Cepstral Distance Measure (CD), Linear
Predicative Code Measure (LPC), and Segmental Spectral
Signal to Noise Ratio (SSSNR) reached values of 6.8781,
4.9614, and -21.5563 dB, respectively. The approach demon-
strated high intelligibility of the recovered audio signal and
was found to be safe, dependable, and effective when used in
secure audio communications. . The suggested approach is
divided into two phases: first, the audio signal is encrypted,
and then it is decrypted using the RSA algorithm. The ob-
tained voice or audio samples are encrypted at the transmitter
using the public key, which was previously produced together
with the private key. The audio samples that have been ci-
phered or encrypted are transferred one after the other across
a communication channel to the recipient, who uses the secret
key to decrypt each sample. In the interest of simplicity, it is
assumed that the communication or transmission channel is
perfect or noise-free. Fig. 2. displays the block diagram of
the approach that is being described.
In 2016, El Bakri et al [13], the security of voice calls
was maintained by employing the RSA encryption technique.
Using an analog-to-digital converter circuit, the voice call
is transformed from analog to digital in this method after it
is received from the microphone. The output signal is then
circuit to be converted back to analog. The original voice
call will be obtained by the receiver by applying the reverse
decryption procedures.