PENERAPAN ALGORITMA AES-128 UNTUK MENINGKATKAN KEAMANAN DOKUMEN DIGITAL DI KANTOR NOTARIS & PPAT HARTATI HADIWIJAYA,SH, PONOROGO

Digitization of documents in a notary office environment provides convenience in document storage and management, but it also poses security risks such as unauthorized access and data leaks. These conditions necessitate a data security mechanism for digital documents used in notarial administrative processes. This study aims to design and implement a web-based document management system using the 128-bit Advanced Encryption Standard (AES) algorithm at the Office of Notary and Land Title Registrar (PPAT) Hartati Hadiwijaya, S.H., Ponorogo Regency. The system development method used is the Waterfall model, consisting of problem identification, literature review, requirements analysis, system design, implementation, and testing. The system was developed using the Hypertext Preprocessor (PHP) programming language and MySQL database, applying automatic encryption when documents are uploaded and decryption when accessed through the preview and download features. Testing was conducted using white-box testing, performance testing, and validation using the Devglan AES Encryption Tool. The results show that the system is capable of performing document encryption and decryption properly without failure. In performance testing, a Resident Identity Card (KTP) document measuring 88.79 kilobytes had an encryption time of 0.000278 seconds, while a Certificate document measuring 1971.96 kilobytes required 0.00399494 seconds for encryption. These results indicate that file size influences the processing time for document encryption and decryption. Consequently, the application of 128-bit Advanced Encryption Standard (AES) can effectively help protect digital documents in a web-based document management system within a notary office environment.