CAS-001 · Question #164
A developer is coding the crypto routine of an application that will be installed on a standard headless and diskless server connected to a NAS housed in the datacenter. The developer has written…
The correct answer is D. 6 and 4. On a headless, diskless server connected to a NAS, video and IDE inputs are unavailable, leaving network timing and keyboard input as the only high-quality, executable entropy sources.
Question
A developer is coding the crypto routine of an application that will be installed on a standard headless and diskless server connected to a NAS housed in the datacenter. The developer has written the following six lines of code to add entropy to the routine:
1 - If VIDEO input exists, use video data for entropy 2 - If AUDIO input exists, use audio data for entropy 3 - If MOUSE input exists, use mouse data for entropy 4 - IF KEYBOARD input exists, use keyboard data for entropy 5 - IF IDE input exists, use IDE data for entropy 6 - IF NETWORK input exists, use network data for entropy Which of the following lines of code will result in the STRONGEST seed when combined?
Options
- A2 and 1
- B3 and 5
- C5 and 2
- D6 and 4
How the community answered
(29 responses)- A3% (1)
- B14% (4)
- C24% (7)
- D59% (17)
Why each option
On a headless, diskless server connected to a NAS, video and IDE inputs are unavailable, leaving network timing and keyboard input as the only high-quality, executable entropy sources.
Line 1 (video) cannot execute on a headless server because there is no video input device, making this combination impossible regardless of audio availability.
Line 5 (IDE) cannot execute on a diskless server because there is no IDE drive present, so this combination cannot produce any entropy.
Line 5 (IDE) cannot execute because the server is diskless, eliminating this combination regardless of whether audio input exists.
The server is headless (no video output, so line 1 cannot execute) and diskless (no IDE drive, so line 5 cannot execute). Network data (line 6) is available because the server connects to a NAS, and its packet-timing unpredictability is a high-quality entropy source. Keyboard input (line 4) is also available since 'headless' means no display rather than no keyboard, and keypress timing is a classic high-entropy source that combines with network data to produce the strongest seed.
Concept tested: Entropy source selection for headless diskless servers
Source: https://csrc.nist.gov/publications/detail/sp/800-90b/final
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