This paper proposes a secure mobile chat with visual approach based on the exchange of color coding. It is a kind of visual encryption algorithm designed by using substitution method together with transposition method. Color code is composed of 6 hexadecimal digit number composition, a total of 16 * 16 * 16 * 16 * 16 * 16 different combinations. This paper is as way to exchange session keys by using a randomly selected color code the resulting color which cloud be served as an exchanged session key. Therefore, some distinct color codes represented as passwords are used in this paper, which will be also exchanged via a Mobile Chat (MC) server. In the other words, the session key for encryption and decryption algorithm is represented as a set of color codes in our proposed scheme. Hence, this paper focuses on how to securely exchange their secret key by using the color codes exchanging. Finally, it could be applied efficiently to be a key exchange mechanism on a secure MC application (APP).
