Audio Encryption and Decryption using the Affine Cipher with the One-Time Pad (OTP)

This research aims to design and implement a hybrid encryption system to secure audio signals, based on the integration of two cryptographic algorithms: Affine Cipher and One-Time Pad (OTP). The Affine Cipher algorithm is a simple and efficient model of classical encryption, while the One-Time Pad algorithm provides a high level of security when using a random, unrepeated key. The proposed system was applied to a digital audio signal, where the signal was first converted to a numerical representation (8-bit), then encrypted using Affine Cipher, followed by the application of OTP encryption to the resulting outputs. The practical evaluation included the use of quantitative measures such as the average quadratic error (MSE), the average absolute error (MAE), and the signal-to-noise ratio (SNR), in addition to the statistical distribution of signals at each stage of the encryption by histogram. The results showed that the loose signal was exactly identical to the original signal (MSE = 0, MAE = 0, SNR = ∞), and statistical analysis of the histogram proved the effectiveness of the system in blurring the frequency patterns of the signal, which enhances its resistance to analytical attacks. The proposed system provides a balance between simplicity of implementation and efficiency in encryption, and is suitable for securing audio data in real-time applications and sensitive systems