Assume that passwords are selected from four-character
combinations of 26 alphabetic characters. Assume that an
adversary is able to attempt passwords at a rate of one per
second.
a) Assuming no feedback to the adversary until each attempt
has been completed, what is the expected time to discover
the correct password?
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Answer / mundialboy346
a. T = seconds = 63.5 hours
b. Expect 13 tries for each digit. T = 13 × 4 = 52 seconds.
| Is This Answer Correct ? | 11 Yes | 0 No |
Answer / amos
a) involves sequences, thus, 26^4 = 456,976 seconds which is worst case hence average case would be 456,976/2 = 228, 488 seconds or 63.7 hours or ~ 2 days.
b) involves multiplication principle, thus, worst case scenario would be 26*4 = 104 seconds hence average case is 104/2 = 52 seconds
| Is This Answer Correct ? | 2 Yes | 0 No |
Answer / joel
Did none of you ever learn about combinations and permutations in math class? Have you ever wondered what the nCr and nPr buttons do on your calculator? If you are to make a combination of 4 out of 26 possible choices, 26 nCr 4 = 14,950 possible different combinations. That is 14,950 seconds. 14,950/60 = 249.17 minutes / 60 = 4.15 hours...
| Is This Answer Correct ? | 1 Yes | 10 No |
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