1. In brute force attack, on average half of all possible keys must be tried to achieve success.

a) True

b) False

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2. If the sender and receiver use different keys, the system is referred to as conventional cipher system.

a) True

b) False

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3. Divide (HAPPY)26 by (SAD)26. We get quotient –

a) KD

b) LD

c) JC

d) MC

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4. Dividing (11001001) by (100111) gives remainder –

a) 11

b) 111

c) 101

d) 110

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5. pi in terms of base 26 is

a) C.DRS

b) D.SQR

c) D.DRS

d) D.DSS

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6. The time required to convert a k-bit integer to its representation in the base 10 in terms of big-O notation is

a) O(log2 n)

b) O(log n)

c) O(log2 2n)

d) O(2log n)

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7. In base 26, multiplication of YES by NO gives –

a) THWOE

b) MPAHT

c) MPJNS

d) THWAE

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8. Division of (131B6C3) base 16 by (lA2F) base 16 yeilds –

a) 1AD

b) DAD

c) BAD

d) 9AD

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9. An encryption scheme is unconditionally secure if the ciphertext generated does not contain enough information to determine uniquely the corresponding plaintext, no matter how much cipher text is available.

a) True

b) False

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10. The estimated computations required to crack a password of 6 characters from the 26 letter alphabet is-

a) 308915776

b) 11881376

c) 456976

d) 8031810176

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Reduce the following big-O natations:

11. O[ ax^{7} + 3 x^{3} + sin(x)] =

a) O[ax^{7}].

b) O[sin(x)].

c) O[x^{7}].

d) O[x^{7} + x^{3}].

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^{7}+ 3 x

^{3}+ sin(x)] = O(ax

^{7}) = O(x

^{7})

12. O[ e^{n} + an^{10}] =

a) O[ an^{10} ].

b) O[ n^{10} ].

c) O[ e^{n} ].

d) O[ e^{n} + n^{10} ].

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^{n}+ an

^{10}] = O[ e

^{n}].

13. O [ n! + n^{50} ] =

a) O [ n! + n^{50} ].

b) O [ n! ].

c) O [ n^{50}].

d) None of the Mentioned

### View Answer

^{50}] = O [ n! ].