ITPEC IP October 2018 Question 38

Tapping of communication content — encrypted data intercepted on the line cannot be read without the key.

Encryption turns data into ciphertext that only the holder of the key can turn back into plaintext. Someone tapping the line or capturing wireless LAN radio still gets a copy of the data, but cannot read it. Encryption therefore protects confidentiality: it stops the content being disclosed, not the data being lost or the service being stopped. Examples are HTTPS for web traffic and WPA2 for wireless LANs.

Answer (c)

Why not others:

• •(a) — an operational error deletes encrypted data just as easily; the protection against loss is a backup
• •(b) — social engineering tricks a person into revealing information, even the password or key itself; the countermeasure is staff training and verification procedures
• •(d) — a DoS attack floods the server with requests to stop its service; encryption does not reduce the load, while filtering and spare capacity do

Key rule: Encryption protects confidentiality only; loss of data and attacks on availability or on people each need their own countermeasures.

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