• Description:
  The Data Encryption Standard (DES) is a symmetric-key algorithm used for encrypting and decrypting data. It uses a 56-bit key and operates on 64-bit blocks of data. DES is based on a series of substitution and permutation operations. It applies 16 rounds of processing, with each round involving expansion, substitution, permutation, and XOR operations. The key undergoes a series of transformations to create round keys, one for each of the 16 rounds.
  
  DES is widely known for its simplicity and efficiency in hardware but is considered insecure by modern standards due to its relatively short key length. Brute-force attacks can easily break DES encryption within a feasible time frame. Despite this, DES played a significant role in the development of cryptographic standards and served as the foundation for subsequent algorithms such as AES.
  
  To perform DES encryption and decryption, both the sender and receiver need to use the same key. DES can be implemented in Java using the Cipher class from the Java Cryptography Extension (JCE). Key generation and handling, as well as file reading and writing, are crucial steps in applying DES to text files for secure data transmission.

• To start the encryption process, select the input file path after setting up the DES encryption GUI.
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• The chosen file location is indicated by the selected file path that shows up in the text field.
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• Select the path of the 'encrypt.txt' file to begin the encryption process.
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• The path of the 'Encrypt.txt' file has been selected for encryption.
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• The files input.txt and encrypt.txt are chosen. When the Encrypt button is clicked, encryption is successfully finished.
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• To start the decryption process, select the encrypt file path after setting up the DES decryption GUI.
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• The chosen file location is indicated by the selected file path that shows up in the text field.
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• Select the path of the 'Decrypt.txt' file to begin the decryption process.
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• The path of the 'Decrypt.txt' file has been selected for decryption.
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• The files encrypt.txt and decrypt.txt are chosen. When the Decrypt button is clicked, decryption is successfully finished.
• The decrypt method uses Data Encryption Standard (DES) Algorithm to decrypt data from an encrypted file. It initializes a Cipher in decryption mode with the provided secret key and decrypts the byte array read from the input file. Finally, it writes the decrypted data to the specified output file, handling any exceptions that might occur.
• READ ENCRYPTED FILE: The readFile method reads the entire content of a file at the Encrypted text file path and returns it as a byte array. It uses Files.readAllBytes() for efficient reading, handling file input as a stream of bytes.
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• Use the same secret key for both encryption and decryption to maintain consistency and ensure accurate data retrieval.
• SECRET KEY : The server generates a Data Encryption Standard (DES) secret key and saves it to a file for secure storage. The client-side application, with a GUI, loads this key from the file when needed. The key is then used for encryption processes in the client-side operations.
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• The result is saved in the encrypted text file, and encryption is applied to the input text file. When a text file is decrypted, its original content is restored.
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