This dissertation has as its object the study of the relationship between encryption and backdoors and their reflexes on different legal institutes: privacy, security, information circulation, data protection, among other points. Considered the scarce jurisprudence on the themes, this study is mostly concentrated in doctrinal research and, also considering the reasonable novelty of discussion in national doctrine, there will be no few foreign sources. Initially, we seek to investigate how the debates about encryption are with discussions about backdoors, starting from some basic definitions about the institutes and, especially the family of ideas that orbits encryption, such as the selectivity of the intelligible and philosophy for behind the decryptness keys. Subsequently, we point to conflict values in the debate, the history of cryptographic wars and the reflexes of encryption in constitutional jurisdiction through ADPF 403 and ADI 5.527. Subsequently, we investigate other circumstances that may be coupled to the debate, but apparently are not properly emphasized. First, analyzing the backdoors sources in the infrastructures connected to present actors and knowledge that can explore these sources more easily and thus access information to the default of encryption through surreptitious methods, especially if considered the prism of transnationality and the opacity of informal collaboration agreements between private intermediaries and other governments. In this sense, we seek to signal to other possible functions of encryption, introducing a tension between different jurisdictions and asymmetries of access to data that are subordinate to interconnected infrastructures. At a last stage, we seek to present some protections against backdoors through the legal institutes available now in the national order, when we draw the framing of encryption as a technical security measure of data protection and secure communications on the Internet, attracting the provisions of the General Law of Data Protection and the Civil Marco of the Internet. Moreover, in the eagerness to confront the opacity and distrust that can turn into any intermediaries collaborating from other governments, we signal to LGPD transparency tools, but we point out to the possible difficulties in this path.