An organisation inserts filler bits into the gaps of an encrypted link so that the volume of traffic it carries looks the same whatever is actually being sent. Which X.800 security mechanism is that?

Answer

Traffic padding

Options - A. Traffic padding - B. Routing control - C. Notarization - D. Authentication exchange - E. Encipherment Why - A. Correct — traffic padding injects filler units into a link’s idle spaces so its observed volume never varies, defeating traffic analysis by hiding the pattern rather than the content. - B. Routing control selects or changes the physical routes data takes so that sensitive data crosses only trusted links. It changes *where* traffic goes, not how much of it appears. - C. Notarization brings in a trusted third party to vouch for properties of an exchange. No third party is involved here. - D. An authentication exchange is a protocol run that establishes an entity’s identity. It happens at setup and says nothing about traffic volume. - E. Encipherment is already in use here — the link is encrypted — and it is precisely what padding is added *on top of*, because encryption hides content while leaving the pattern visible.

ITU-T X.800 (OSI security architecture) — not in Stallings & Brown 5e