Which security discipline is specifically concerned with protecting transmissions from interception or exploitation by methods other than cryptography?

• A. Transmission Security
• B. Emission Security
• C. Physical Security
• D. Operational Security

Answer: (A)

Transmission Security protects the transmission channel itself from being intercepted or exploited by methods other than cryptography. It focuses on the way the signal is carried—using techniques that make it harder for an adversary to detect, intercept, or exploit the communication regardless of the content’s encryption. Examples include frequency hopping or spread-spectrum methods that disguise or broaden the signal, directional antennas to limit where the signal can be received, and shielding or emission controls to prevent leakage.

Emission Security, by contrast, deals with unintentional radiations and emanations from equipment that could reveal sensitive information, so it’s about reducing or controlling those leaks. Physical Security concerns protecting the hardware and facilities from tampering or theft. Operational Security focuses on policies and actions that protect information by managing how it’s handled and shared.