CISSP-ISSAP · Question #7
Maria works as a Network Security Officer for Gentech Inc. She wants to encrypt her network traffic. The specific requirement for the encryption algorithm is that it must be a symmetric key block…
The correct answer is C. DES. DES (Data Encryption Standard) is a symmetric key block cipher that encrypts data in 64-bit blocks using a 56-bit key, directly satisfying both requirements. PGP (B) is clearly wrong because it is an encryption framework that relies on asymmetric (public/private key)…
Question
Maria works as a Network Security Officer for Gentech Inc. She wants to encrypt her network traffic. The specific requirement for the encryption algorithm is that it must be a symmetric key block cipher. Which of the following techniques will she use to fulfill this requirement?
Options
- AIDEA
- BPGP
- CDES
- DAES
How the community answered
(15 responses)- A13% (2)
- B7% (1)
- C80% (12)
Explanation
DES (Data Encryption Standard) is a symmetric key block cipher that encrypts data in 64-bit blocks using a 56-bit key, directly satisfying both requirements. PGP (B) is clearly wrong because it is an encryption framework that relies on asymmetric (public/private key) cryptography, not a symmetric block cipher.
Important nuance for exam takers: This question has a weakness - both IDEA (A) and AES (D) are also symmetric key block ciphers, so if your exam marks only DES as correct, it may be testing recognition of DES as the original, canonical U.S. federal standard for symmetric block encryption. AES was designed to replace DES after its 56-bit key was deemed too weak; IDEA is a lesser-known alternative. If your exam accepts multiple correct answers, A and D are also valid.
Memory tip: PGP = "Pretty Good Privacy" = public/private keys (asymmetric) - the odd one out. DES, AES, and IDEA all share the block cipher pattern: fixed block size + shared secret key.
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