Securing data that is going to be transmitted through the network is a requirement for the majority of applications. Nowadays, devices are designed with data encryption capabilities so that they achieve confidentiality in transit, i.e., adversaries looking at the network can not read the content of the encrypted data. With the advent of quantum computers, however, confidentiality is again a concern. There are asymmetric cryptographic algorithms in use today that are known to be vulnerable to an “ideal” quantum computer. Even though this idealized quantum computer is not yet operational (at least to the public knowledge), confidentiality must be thought of in the long-term. If an adversary is capturing network traffic today, that adversary will be able to break confidentiality in the future, aided by a quantum computer, since experts expect that quantum computing will evolve steadily. Considering the TLS protocol, used in the majority of the Internet’s connections, today’s users can not expect confidentiality in the long term due to the quantum threat. This chapter explains how this threat is a concern for today’s users, also by discussing a variety of ways of how they can be protected.