Digital File Encryption Using The Advanced Encryption Standard (AES) in Gcm Mode: A Vb.Net Implementation with Nist Security and Performance Evaluation

Abstract

This research presents the design of an integrated software system for data encryption and the protection of digital files against unauthorized access. The system utilizes the Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM) with a 128-bit key, implemented in Visual Basic .NET via an interface that supports both encryption and decryption with full content recovery. The random components used for key and initialization vector generation were subjected to the NIST statistical test suite—comprising 14 tests with an acceptance threshold of p > 0.01—and successfully passed all tests, maintaining values ​​well below the 0.2 failure threshold. The system features a key space of 2¹²⁸ and an exhaustive search time of 5 × 10²¹ years (at a rate of 50 billion keys per second). It recorded encryption and decryption times of 1.6 seconds and 1.1 seconds, respectively—compared to 3 and 1 seconds for DES, and 7.3 and 4.9 seconds for RSA—while ensuring complete data integrity without significant file size expansion. The results confirm the system's suitability for protecting stored files and recommend its broader adoption.