
Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Transcribed Image Text:We analyzed a program which was supposedly used for cracking some cryptographic algorithms. During the investigations we determined
that the program input size can be varied in a wide range and for N-bit input the program result is also always N bit long. Additionally we
found that the program working time depends significantly on input length N, especially when N is greater than 10-15. Our test also
revealed, that the program working time depends only on input length, not the input itself.
During our tests, we fixed the following working times (with an accuracy of one hundredth of a second):
N=2-16.38 seconds
N = 5-16.38 seconds
N = 10-16.44 seconds
N=15-18.39 seconds
N=20-1 minute 4.22 seconds
We also planned to test the program for N=25 and N = 30, but for both cases the program didn't finish within half an hour and was forced
to terminate it. Finally, we decided for N= 30 to not terminate the program, but to wait a little bit longer. The result was 18 hours 16 minutes
14.62 seconds. We repeated the test for N= 30 and it gave us exactly the same result, more than 18 hours.
Tasks:
a) Find the program working times for the following three cases - N = 25, N = 40 and N = 50.
b) Explain your result and solution process.
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