A security administrator has been asked to select a cryptographic algorithm to meet the criteria of a new application. The application utilizes streaming video that can be viewed both on computers…

Question

Options

• AUse AES in Electronic Codebook mode
• BUse RC4 in Cipher Block Chaining mode
• CUse RC4 with Fixed IV generation
• DUse AES with cipher text padding
• EUse RC4 with a nonce generated IV
• FUse AES in Counter mode

• A
  19% (5)
• B
  4% (1)
• C
  67% (18)
• D
  4% (1)
• E
  7% (2)

Explanation

The requirement is low-overhead transport encryption for streaming video on multiple device types. AES in Counter (CTR) mode (F) is the strongest recommendation: it converts AES into a stream cipher, is highly parallelizable, has no padding overhead, and is hardware-accelerated on modern devices - ideal for streaming. RC4 with a nonce-generated IV (E) would be acceptable as a stream cipher for low overhead, but the listed correct answer is RC4 with a Fixed IV (C). Note: in practice, a fixed IV with RC4 is a serious vulnerability (the same keystream is reused), so this appears to be an older exam question where RC4 was still prevalent. AES in ECB mode (A) is insecure due to pattern leakage. RC4 in CBC mode (B) is a misuse - CBC is a block cipher mode and RC4 is a stream cipher. AES with cipher text padding (D) adds overhead and is inappropriate for streaming.

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