Integration of Key Derivation Function (KDF) Development for Advanced Encryption Standard (AES) 256 Key Generator in Digital File Security

Digital file security has become increasingly crucial along with the rapid development of information technology. The Advanced Encryption Standard (AES) 256 bit algorithm is a strong cryptographic solution; however, its effectiveness greatly depends on the quality of the encryption key used. The use of weak keys can significantly reduce the level of security. This research aims to enhance the security of the AES key generation process by integrating the development of a Key Derivation Function (KDF). The proposed KDF utilizes a 512 bit external key that is divided into two blocks, processed using an XOR operation, and subsequently transformed with the AES SubBytes substitution to generate a more complex 256 bit derived key. The system is implemented as a desktop application with a graphical user interface (GUI) using the Python programming language with the tkinter and cryptography libraries. The test results show that the application successfully encrypts and decrypts various digital file formats (.pdf, .docx, .xlsx, .png, .mp3, and .mp4). Encrypted files cannot be accessed and can only be restored to their original form through the decryption process with the correct key. The integration of this KDF has proven effective in strengthening the key for the AES 256 algorithm, thereby providing an additional security layer to protect digital files from unauthorized access.