The exchange of confidential information has always been a problem that challenged us. The techniques knowledge that aimed to concealing a message dates back to some centuries BC, such as steganography and cryptography Steganography consists on the technique of hiding the message that will be sent however, without, hide its meaning. However, encryption is the technique of hide the meaning of the message through its coding, which can be done in several ways, whose content can only be decoded by the recipient, who has the decryption key. These techniques have evolved over time, especially cryptography, because it has a more complex decoding nature and, therefore, it is more suitable today. That's because, with the development of new communication technologies, guarantee information security has become a greater concern than it used to be. On this side, we highlight the internet, which, in addition to requiring security, it’s shared by the vast majority of our students. As Internet security uses the encryption, and it’s associated with mathematical models, we can explore the use of encryption in classroom in order to arouse the student’s curiosity, his interest in subjects, often difficult to understand, given their maturity to face them. Theories as functions and their inverse functions, arithmetic of the residual classes, etc., can be worked in classroom using the Caesar Code, and it allows the teacher to deal in a didactic way with the differences existing in the classroom.