23. d. All four items are examples of procedural security controls for recognizing trusted CA and RA roles. The CA is a trusted third party that generates, issues, signs, and revokes public key certificates. The CA can delegate responsibility for the verification of the subject’s identity to an RA. The RA is a trusted entity that establishes and vouches for the identity of a subscriber to a credentials service provider (CSP).
24. Which of the following need not be subject to maintenance of special accounting records for cryptographic keying materials?
a. Ephemeral keys
b. Encrypted keys
c. Decrypted keys
d. Key encrypting keys
24. a. Ephemeral keys are cryptographic keys that are generated for each execution of a key establishment process and that meet other requirements of the key (for example, unique to each message or session and short-lived). It may not be practical or necessary to maintain accounting records for relatively short-lived keys such as ephemeral keys. This is because user devices (for example, user entities at client nodes) generate ephemeral keys, and they are intended for use within the client node.
The other three choices need accounting records. Encrypted keys are encrypted with a key encrypting key to disguise the value of the underlying plaintext key. The key encrypting key is used for the encryption or decryption of other keys.
25. For the willful or negligent mishandling of cryptographic keying materials, the consequences of policy violation should be commensurate with which of the following?
a. Actual harm
b. Known harm
c. Potential harm
d. Guaranteed harm
25. c. The consequences of willful or negligent mishandling of cryptographic keying materials (for example, keys and initialization vectors) should be commensurate with the potential harm that the policy violation can result in for the organization and other affected parties. The actual harm cannot be known in advance, and there is no guarantee that harm will occur for certain.
26. A cryptographic keying material is compromised during the course of regular or normal work. Which of the following actions may not be necessary during the compromise recovery process?
a. Key destruction
b. Notification of users of compromised keys
c. Emergency key revocation
d. Replacement of the compromised keys
26. a. Notification of users of compromised keys, emergency key revocation, and secure replacement of the compromised keys are a part of normal recovery procedures. Key destruction must take place only when an external attacker is involved, not when user errors and system problems are involved during the course of regular work. The other three choices are normally used during the compromise recovery process.
27. For the encapsulating security protocol (ESP) header of the Internet Protocol security (IPsec), which of the following cryptographic algorithms or modes provides both encryption and integrity services to the ESP-protected traffic?
a. AES-128 bit in cipher block chaining (CBC) mode
b. AES-128 bit in counter mode
c. HMAC SHA1-96 bit
d. AES-128 bit in counter mode with CBC-MAC
27. d. The AES-128 bit key in counter mode with CBC-MAC provides both encryption and integrity protection. The AES-128 bit in CBC mode and the AES-128 bit in counter mode provide only encryption whereas the HMAC SHA1-96 bit provides only integrity protection. The encrypted ESP should not be used without integrity protection because the ESP needs both encryption and integrity protection.
28. Within the Internet Protocol security (IPsec) protocol suite, which of the following should not be used because it introduces unnecessary complexity in processing?
a. Authentication header (AH)
b. Encapsulating security protocol (ESP)
c. Security association (SA)
d. Internet key exchange (IKE)
