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Because these numbers have a common factor with (p-1)(q-1).

Because they make encryption faster.

These are first five prime numbers, any other prime number would be larger.

Select the false statement

All AES rounds are identical.

AES operates in GF(2^8).

AES with a key size of 128 bits has 10 rounds.

AES encryption and decryption are not identical, i.e., they require (slightly) different algorithms.

In the finite field GF(2³) defined by the irreducible polynomial

m(x) = x³+x+1,

find the multiplicative inverse of the polynomial x²+1. In other words, determine the polynomial A(x) such that

(x²+1) A(x) ≡ 1 (mod x³+x+1)

What is the result when reducing x⁵ mod (x⁵+x²+1)? (you can use "^" to indicate exponents eg. x⁵ = x^5)

Which polynomial is not in the set of GF(2³)?

x³+x+1

x²+x+1

x+1

What is the drawback of using Finite Fields of form GF(p) with a prime p in a cryptographic algorithm?

The algorithm cannot be made secure enough, even for large values of p.

It is not easy to generate a relatively secure prime number.

We will waste space on a computer that operates on multiples of 2 (e.g., 2¹⁶ or 2³²).

Not all elements have a multiplicative inverse, hence we cannot do decryption.

Note: Only the result is requested, namely a numeric value. No procedure needed.

How many numbers are relative prime to 10?

Select the false statement:

In AES the key size is always the same as block size.

AES operates using modular polynomial arithmetic over GF(2ⁿ).

Encrypting or decrypting a block in AES takes either 10, 12, or 14 rounds.

AES s a non-feistel cipher.