Analysis of Various Scenarios Encryption on Digital Image Color Using Data Encryption Standard (DES) Algorithm

Abstract

Cryptographic techniques are widely applied to maintain the confidentiality of a message. However, most cryptographic techniques are currently still being performed on the entire content of the message, so that they require high computation time. Therefore, in this research we designed several test scenarios to encrypt partially the contents of the messages which can lead to faster computation while still maintaining the quality of information confidentiality. In this research, we used BMP image files of digital color photographs with color depth 24-bit consisting of three different objects. Encryption technique used is Data Encryption Standard (DES) with operating mode Electronic Codebook (ECB). Analysis is performed on computation time and quality of the encryption of each scenario. The quality of encryption is computed using Peak Signal to Noise Ratio (PSNR) and a survey to 30 respondents. Respondents will compare the original image file (plaintext) and encrypted image (ciphertext). Results of the analysis showed that the computation time is not only affected by the resolution of image files but also by the choice of the encryption scenarios. The encryption with the best, indicated by the smallest PSNR values was generated by the scenario 1 (scenario full) with the average value of 33,62 dB, while the largest PSNR value was generated on the scenario 8 (head section) with an average value of 39,67 dB. Encryption quality visually assessed based on the results of the survey. The results of the survey concluded that, the best encryption quality was achieved in scenario 1 with a value of 93,33%, and the worst in scenario 7 (bottom scenario) with a value of 28%. In this research, the computation time of scenario 8 is one third of the computation time of scenario 1. Conclusions obtained from this research is that by applying the appropriate encryption scenario, shorter computation time can be achived while maintaining effective encryption.