Monoxalyze is a carbon monoxide breathalyzer that works with a user's smartphone to verify smoking cessation. Monoxalyze verifies cessation by creating transitive trust between the user, the smartphone, and the Monoxalyze device; the links in this chain are created through facial recognition, visible light authentication, and exhalation verification respectively. These links of trust ensure that the correct user is exhaling sufficiently through the expected Monoxalyze device.