IMPLEMENTASI ALGORITMA KOMPRESI LEMPEL-ZIV 4 PADA SISTEM INFORMASI PERGURUAN TINGGI SEBAGAI TAHAP PRA-ENKRIPSI DENGAN AES-256

​The increasing volume of digital data in the education sector necessitates enhanced information security measures. This study proposes integrating the Lempel-Ziv 4 (LZ4) compression algorithm as a pre-encryption stage and the Advanced Encryption Standard (AES-256) to replace the existing Caesar Cipher implementation in the Faculty of Engineering Information System (SimFT). LZ4 was selected for its compression speed, while AES-256 is a widely adopted encryption standard. Implementation was conducted on SimFT's file upload module and evaluated using DOCX, PDF, and PNG file types. Test results indicate LZ4 achieved storage savings of 21.4%–29.8% for DOCX and PDF files, with a compression ratio of ~1.00 for PNG files. Compression execution times ranged from 65.8 ms to 81.9 ms, with AES-256 encryption adding 0.9 ms to 9.5 ms. Data integrity was confirmed via SHA-256 hash verification across 1,200 samples. Findings demonstrate that the LZ4 and AES-256 combination can improve storage efficiency and security in SimFT. This study is limited to three file types and implements multithreading for scalability, with an in-depth analysis of multithreading being beyond the scope of this paper.