Enhancing Communication Security with 3DES and Spread Spectrum Technologies

As society moves towards the digital age, data security has become an increasingly important issue in wireless communication. To address this problem, the use of encryption techniques has become crucial. In this we studied the Triple Data Encryption Standard (3DES) from theory to practical application, and proposes a wireless spread spectrum system utilizing Direct Sequence Spread Spectrum (DSSS) technology, Quadrature Phase Shift Keying (QPSK) modulation, and 3DES encryption/decryption for secure and reliable data transmission. The system is able to efficiently recover the received signal, even in the presence of interference and noise, as demonstrated by the significantly lower Bit Error Rate (BER) of the received signal compared to the original transmitted binary sequence. The effectiveness of the system is demonstrated through simulation results, indicating that it offers a promising solution for wireless communication applications where secure and reliable data transmission is essential.


Introduction
The growth of digitization in many industries has led to a vast amount of data being shared and communicated through wireless channels.Unfortunately, the rise in data exchange has also resulted in an increase in unauthorized access, illegal usage, and alteration of transmitted and stored data.To combat these issues, encryption technology is essential in protecting software systems and ensuring the confidentiality, integrity, and security of data.[1].
Symmetric encryption algorithms are widely used in many cryptographic applications.Triple Data Encryption Standard (3DES), an improved version of the original DES algorithm [2], provides enhanced security and reliable encryption.Previous research has shown that the 3DES algorithm can improve the complexity and security of data encryption in various scenarios [4]- [8].Extensive analyses of the security features and design steps involved in the most widely used symmetric encryption algorithms, including DES, 3DES, and AES, are presented in [3].In [4], the authors implemented the 3DES algorithm by encrypting data multiple times with the DES algorithm, effectively avoiding weaknesses in single encryption and significantly enhancing encryption strength.In [5], a simple S-box permutation method was employed to improve the balance between speed and security in the 3DES algorithm.A systematic design methodology combining chaotic synchronization with 3DES to conduct double encryption is proposed in [6].However, [7] demonstrated successful attacks on a 32-bit CPU smart card using a power analysis technique on a 3DES hardware module.To address this issue, [8] utilized a Reverse Data Hiding Algorithm in conjunction with 3DES to ensure the security and confidentiality of image data.
Studying spread spectrum communication is crucial due to its significant benefits in terms of security, interference resistance, efficient use of frequency spectrum, versatility, and technological advancements.Spread spectrum communication provides enhanced security by making it difficult for unauthorized users to intercept or decode transmitted data, while also being resistant to interference, making it ideal for use in crowded environments.Additionally, it allows multiple users to share the same frequency band, which maximizes the use of the limited frequency spectrum available.Moreover, spread spectrum communication has various applications in military, medical, and commercial fields, making it versatile.Finally, the study of spread spectrum communication has led to advancements in communication technologies, such as CDMA and Wi-Fi, which have revolutionized the way we communicate.
The contributions of this paper are summarized as follows.
 This study encompasses a comprehensive examination of the 3DES, spanning from its theoretical foundations to its practical application. The study also proposes a wireless spread spectrum system that employs DSSS technology, QPSK modulation, and 3DES encryption/decryption to facilitate secure and dependable data transmission. The system is capable of proficiently recovering the received signal, even in the presence of interference and noise, as evidenced by the significantly BER of the received signal in comparison to the original transmitted binary sequence.The rest of the paper is organized as follows.Section 2 presents the concept, basic principles, and performance analysis of 3DES algorithm.The proposed wireless spread spectrum communication model and components analysis are given in Section 3. In Section 4, we provide simulation results and Section 5 concludes this paper.

Basic principles of the 3DES encryption algorithm
3DES [8] is a symmetric encryption algorithm that provides a higher level of security than the original Data Encryption Standard (DES).3DES encrypts data using three different keys and three rounds of encryption, hence the name "triple".Each round of encryption uses a different key, and the keys are either generated randomly or derived from a user-supplied passphrase.3DES is a widely used encryption algorithm and is considered secure for most applications, although it has been largely replaced by more modern algorithms such as AES (Advanced Encryption Standard) in recent years.The working principle of 3DES is based on the use of a symmetric encryption algorithm that applies multiple rounds of encryption to plaintext data using a set of three secret keys.
The algorithm works as follows [9][10]:  Key Generation: Three secret keys are generated, or derived from a user-supplied passphrase, and are used to encrypt the plaintext data. Encryption: The plaintext data is first encrypted using the first key, and the resulting ciphertext is then decrypted using the second key.This process is repeated again, with the resulting ciphertext being encrypted using the third key.The final result is the encrypted ciphertext. Decryption: The decryption process is the reverse of the encryption process.The ciphertext is first decrypted using the third key, and the resulting plaintext is then encrypted using the second key.Finally, the resulting ciphertext is decrypted using the first key, resulting in the original plaintext.The use of multiple rounds of encryption and decryption makes 3DES more secure than the original DES algorithm, which used a single key.The key size for 3DES is 168 bits, which is larger than the key size for DES (56 bits), making it more resistant to brute-force attacks.Figure 1. is the structure diagram of the DES algorithm.

Implementation of encryption/decryption algorithm
The 3DES algorithm's encryption and decryption processes can be represented by Ek() and Dk(), respectively.The algorithm uses a key ki (i = 1, 2, 3), plaintext P, and secret table C. The 3DES algorithm mainly involves three steps: Initial and Final Permutation, Round Function, and Key Generation.The encryption process in 3DES uses three keys, shown as following [11]: k1, k2, and k3 determine the security of the algorithm.If the three keys are all different, it is essentially equivalent to using a single key with a length of 168 bits for encryption.Over the years, 3DES has been relatively secure against brute force attacks.If the data does not require such high security, k1 can be set equal to k3.In this case, the effective key length is 112 bits.The decryption process simply reverses the encryption process.

Study of the Application Scenarios
To study the validity and reliability of the 3DES algorithm, we set up a simulation test platform for data transmission encryption and decryption in a local area network communication environment.Two computers are named A and B, representing the sender and receiver, respectively.Five sets of data of the same size are selected for communication, and 50 brute force attacks are artificially set to attempt to crack the security key of the data transmission.The simulation experiments are conducted using the 3DES encryption algorithm to encrypt the data.The security performance of the algorithm and the analysis of encryption and decryption efficiency are presented below.

2.3.1.
Security performance analysis of the algorithm.After 50 brute-force cracking attacks, the average damage degree of each transmission after data communication encrypted by the algorithm is expressed in %, as shown in Table 1.The security performance of the third and fourth groups of data encrypted by the 3DES encryption algorithm is weak, with 0.15% and 0.12% data damaged.In general, the security performance of data encrypted by the 3DES encryption algorithm has been able to meet most scenarios of the same type, and the effectiveness of data encryption has been guaranteed.

Efficiency analysis of algorithm encryption and decryption.
In the process of the same experiment above, the average time cost occupied by each transmission was recorded at the same time, in ms, as shown in Table 2.
Table 2. Efficiency analysis of algorithm encryption and decryption.The algorithm's time control is within a reasonable range, which not only ensures the efficiency of encryption, but also reduces the unnecessary time cost.Based on the results of our experiments, which showed that the 3DES algorithm provides both efficiency and security, we implement this algorithm in our proposed wireless communication system.

The Proposed System Model
Direct Spread Spectrum Communication (DSSC) [12][13] is a crucial technology for both civil and military communication systems due to its strong anti-jamming ability and low probability of interception.DSSC utilizes advanced signal processing techniques like frequency hopping and spreading the signal over a wide frequency band to ensure reliable and secure communication.This makes it difficult for unauthorized listeners to intercept the communication and also improves the overall reliability of the communication system.DSSC's ability to maintain a reliable connection, even in the presence of interference and jamming, makes it an essential tool in critical communication applications where secure transmission is a top priority.The system block diagram is shown in Figure 4.The designed spread spectrum wireless communication system consists of signal generator, channel encoder, QPSK modulator, spread spectrum, peseudonoise generator, 3DES encryption, filter, AWGN channel, amplifier, 3DES decryption, despreading, QPSK demodulator, channel decoder, received signal and BER comparison.

Analysis of each components
The proposed wireless communication system involves several components and processes to transmit and receive data accurately.At the transmitter, the signal generator generates a binary signal representing the data to be transmitted.The channel encoder adds redundant information to the signal for error detection and correction.The encoded signal is then modulated using a QPSK modulator, and then spread using DSSS technology.The Pseudonoise (PN) generator is responsible for generating a binary sequence to spread the signal over a wider frequency band.The spread signal is encrypted using the 3DES algorithm.At the receiver, the received signal is amplified, filtered, and then decrypted using the 3DES decryption algorithm.The signal is then despread using DSSS, demodulated using a QPSK demodulator, and processed by a channel decoder to detect and correct any errors.BER of the received signal is compared to that of the original signal to evaluate the system's performance.

Simulation and Results
In this section, we present the results of our simulation, as well as the corresponding analysis.We will discuss the key findings and implications of our analysis in the following sections.
Figure 5 shows the binary sequence produced by the signal generator as the input data of the wireless communication system.Figure 6 shows the signal that has been processed by the channel encoder and modulated using QPSK modulation.The spread signal using DSSS technology is shown in Figure 7, and Figure 8 is the power spectrum displayed in the frequency domain, obtained from processing the Fast Fourier Transform (FFT) algorithm.Figure 9 is the encrypted signal transmitted over the air via the AWGN channel.The signal is weakened during transmission, so it is amplified to boost its strength.After amplification, the signal is passed through another filter to remove any noise or distortion that may have been introduced during transmission.At the receiver's end, the signal is first decrypted using the 3DES decryption algorithm.The demodulation process then begins with the QPSK demodulator and is then subjected to dispreading using the same PN sequence used for spreading at the transmitter end.The channel decoder then processes the dispread signal, utilizing the redundant information added during encoding to detect and correct any errors that may have occurred during transmission.The recovered signal shown in Figure .10. Finally, a BER comparison is performed to compare the original transmitted binary sequence with the received binary sequence, which is shown in Figure 11.The comparison of the BER of the original and received signals revealed that the received signal had a significantly lower error rate, indicating that although the transmission had been subject to interference, our system recovered the received signal efficiently.

Conclusion
In this paper, we studied the 3DES and proposed a wireless spread spectrum system based on the 3DES.According to the simulation results presented in this paper, we have demonstrated the effectiveness of a wireless communication system utilizing DSSS technology, QPSK modulation, and 3DES encryption/decryption for secure and reliable data transmission.The system was able to efficiently recover the received signal, even in the presence of interference and noise, as demonstrated by the significantly lower BER of the received signal compared to the original transmitted binary sequence.Overall, the system presented in this paper offers a promising solution for wireless communication applications where secure and reliable data transmission is essential.Future work could focus on optimizing the system for specific applications and exploring other modulation and encryption techniques to further improve performance.

Figure 1 .
Figure 1.The DES algorithm Figure 2. Key generation process for 16-round of DES

Figure 2 .
is the Key generation Process for 16-Round of DES. and Figure3. is the diagram of the process of encryption and decryption.

Figure 4 .
Figure 4. Spread spectrum wireless communication system

Table 1 .
Security performance analysis of the algorithm.