Symmetric Ciphers Questions and Answers – The AES Algorithm – II

This set of Cryptography Puzzles focuses on “The AES Algorithm – II”.

1. Conversion of the Plaintext MANIPALINSTITUTE to a state matrix leads to
a)

b)

c)

d)

b)

c)

d)

Answer: d
Explanation: First convert the state matrix to their equivalent ASCII values and then perform XOR operation.

3. The multiplicative inverse of 0x95 in AES where m(x)=x⁸+x⁴+x³+x+1 is
a) 0x8F
b) 0xF8
c) 0x8A
d) 0xA8
View Answer

4. In AES, to make the s-box, we apply the transformation
b’_i = b_i XOR b_(i+4) XOR b(i+5) XOR b_(i+6) XOR b_(i+7) XOR c_i
What is c_i in this transformation?
a) c_i is the ith bit of byte c with value 0x63
b) c_i is the ith bit of byte c with value 0x25
c) c_i is the ith bit of byte c with value 0x8F
d) c_i is the ith bit of byte c with value 0x8A
View Answer

5. The S-box value for byte stored in cell (6,D)
a) 0x3C
b) 0x7F
c) 0xFD
d) 0x4A
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6. The S-box value for byte stored in cell (B,3)
a) 0x3C
b) 0xB3
c) 0x4F
d) 0x90
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7. The S-box value for byte stored in cell (3,3)
a) 0xC3
b) 0x3C
c) 0x44
d) 0x9B
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8. The inverse s-box permutation follows,
b’_i = b_(i+2) XOR b(i+5) XOR b_(i+7) XOR d_i
Here d_i is
a) d_i is the ith bit of a byte ‘d’ whose hex value is 0x15
b) d_i is the ith bit of a byte ‘d’ whose hex value is 0x05
c) d_i is the ith bit of a byte ‘d’ whose hex value is 0x25
d) d_i is the ith bit of a byte ‘d’ whose hex value is 0x51
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9. The Inverse S-box value for byte stored in cell (3,3)
a) 0xC3
b) 0x66
c) 0x1F
d) 0x9B
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10. The Inverse S-box value for byte stored in cell (6,3)
a) 0x00
b) 0x11
c) 0x01
d) 0x04
View Answer

11. The Inverse S-box value for byte stored in cell (D,2)
a) 0x5F
b) 0x2D
c) 0x7F
d) 0x5D
View Answer

12. What is the Shifted Row transformation for the matrix bellow?

a)

b)

c)

d)

To practice puzzles on all areas of Cryptography, here is complete set of 1000+ Multiple Choice Questions and Answers.