| Resumen |
Each new image cryptosystem aims to achieve improved security results, with entropy being one of the primary measures for quantifying its security. For 8-bit images, the ideal entropy value is 8.0. However, various encryption algorithms typically get values close to this ideal, such as 7.999, but not exactly 8.0. To address this, we propose a complementary algorithm designed to increase the entropy achieved by cryptosystems. This algorithm adds new pixel rows to the encrypted images to achieve a uniform histogram and consequently obtain an entropy value of 8.0. The pixels in these additional rows are assigned the missing intensity values to fit a uniform distribution. To test the proposal, it was applied to four images initially encrypted using the AES-CBC cryptosystem, increasing the entropy from 7.9992 to 8.0 and achieving the highest level of security according to this measure. Although this approach involves a 10% increase in the total number of pixels, it is more efficient compared to other methods that achieve lower entropy values with a larger increase in image size. Finally, this algorithm is compatible with any image cryptosystem for uncompressed images, enhancing their entropy and security. © 2024 IEEE. |
