DES (Date Encryption Standard) Implementation

Authors: Leo Martinez III

Contact: leo.martinez@students.tamuk.edu

Created: Spring 2024

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This C++ program implements the DES Cipher, a type of block cipher, for encrypting and decrypting messages.

Encryption:

• The DES_Encrypt.cpp/.exe script takes a plaintext and a 56-bit key as input.
• It performs an initial permutation (IP) on the 64-bit plaintext.
• The 64-bit block is divided into two 32-bit halves, left (L) and right (R).
• The function performs 16 rounds of Feistel network operations using the subkeys derived from the key.
• In each round, the right half is expanded, XORed with the subkey, and passed through S-boxes for substitution.
• The results are then permuted and combined with the left half.
• After 16 rounds, the left and right halves are swapped, and a final permutation (IP^(-1)) is applied.
• The resulting 64-bit block is the ciphertext.

Decryption:

• Use the same DES algorithm, but reverse the key order of the generated keys

Note:

• Program was created in VS Code using C++

Here is a brief explanation of the items:

• src: folder that contains the source code C++ script (.cpp)
• bin: contains the corresponding compiled .exe version.
• README.md: contains most basic information about the project
• LICENSE: Contains license information in regards to the Github repository