This dissertation proposes to introduce in the math class of the elementary school a theme that brings meaning and interest to the students and, from it, it is possible to develop new and classic content, relevant discipline at this level of education. The theme chosen was the encryption that made possible the development of a historical approach of its development until the RSA code, the promotion of discussions on the current relevance of the subject until our days and working with important content of mathematics. In order to improve and evaluate the proposal, a small application in a public school was made, through a workshop, with results quite satisfactory. It is intended that this work is more a source to assist several teachers in the construction of new pedagogical proposals adapted to the reality of each classroom with motivating, meaningful and contemporary look.