What term describes the practice of preventing unauthorized access to information through analyzing electromagnetic emanations?

The term that describes the practice of preventing unauthorized access to information by analyzing electromagnetic emanations is known as "Tempest." This concept is grounded in the understanding that electronic devices emit electromagnetic signals as they operate, which could potentially be intercepted and exploited by malicious actors to gain access to sensitive information.

Due to these risks, security measures are implemented to mitigate the threat of eavesdropping or interception of these emanations. The Tempest standards provide guidelines on how to develop secure systems and environments that limit or eliminate the chances of such unauthorized access through electromagnetic sources.

While the other terms mentioned may relate to security issues—"bugging" typically involves illicit surveillance through audio recording devices, and "veiling" does not specifically pertain to electromagnetic protection—they do not encompass the specific focus on electromagnetic emanations that Tempest represents. Hence, Tempest is the correct and most precise term for this particular practice.