The Cryptography of Secret Messages Using Block Rotation Left Operation

Abstract: Long and short text messages are widely transmitted through various communication media, and some of these messages may be very secret or of a special nature, which requires protecting them from the danger of abusers, intruders, or data hackers. Given the importance of protecting text messages, a novel method will be presented focusing on simplifying the procedures to protect data and make the hacking process difficult.A high-level protection method will be provided using the complicated variable content private key; this key can be easily changed without changing the sequence of operations used in the encryption and decryption phases.A secret color image is to be used to generate the private key;both the sender and receiver must save this image, and the selected image key can be easily resized to get a key equal to the secret message length.To increase the degree of protection, it is recommended to divide the text message into blocks with a selected size, the sender and receiver must determine the size, and the byte in each block is to be combined into one vector. This vector will be rotated left using a specified number of bits determined by the sender and receiver.The proposed method will be implemented using various color images and text messages, and the results will be compared with other methods to prove the achievements obtained by the proposed method.