Partial Image Encryption Using Cellular Automata

In this work is proposed a partial image encryption method based on the synchronization of the cellular automaton rule 90. The security analysis proves that this cryptosystem is resistant to different tests and attacks such as the Chosen/Knownplain image attack and bit-replacement. This algorithm is a variant from another encryption algorithm named ESCA, in this case we modified the ESCA system to a partial encryption version reducing the latency time up to a 50%. This version has two changes a)it only encrypts the three most significant bits, and b) the bits of the secret key are rotated instead of calculating a key for each block of plaintext. These changes allow to reduce the latency time and according to the tests do not compromise the security. This proposal could be a feasible and secure option for real-time applications.