<![CDATA[The increasing use of digital and multimedia files requires cryptographic schemes that can process various file formats efficiently. This study aims to implement and analyze the performance of a hybrid cryptographic scheme combining RSA-OAEP and Extended Vigenère Cipher for multimedia file encryption. The test data consist of JPG, MP4, TXT, PDF, and ZIP files with different sizes. In the developed system, each file is read directly as a byte array. The file content is encrypted using Extended Vigenère Cipher with modulo 256 operation, while the Extended Vigenère key is encrypted using RSA-OAEP with SHA-256. The encryption output is stored in .enc format, containing metadata, RSA public key, encrypted key, and ciphertext, while the RSA private key is stored separately in .pem format. The evaluation was conducted based on encryption and decryption success, processing time, throughput, encrypted file size, and Shannon Entropy. The results show that all test files were successfully encrypted and decrypted without changing the size of the decrypted files. The largest file, an 82 MB ZIP file, was encrypted in 0.314 seconds and decrypted in 0.251 seconds. The encryption throughput ranged from 28.16 MB/s to 337.62 MB/s, while the decryption throughput ranged from 28.11 MB/s to 337.73 MB/s. The Shannon Entropy values of the encrypted files ranged from 7.8 to 8, indicating a more uniform byte distribution in the ciphertext. However, Shannon Entropy is used only as a supporting metric to observe ciphertext characteristics, not as a sole indicator of cryptographic security. Therefore, this study positions the proposed scheme as a performance analysis of hybrid RSA-OAEP and byte-based Extended Vigenère Cipher for multimedia file encryption.]]>
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