Let F(k,.) be a pseudo-random function and k denote its input key.

Which of the following functions P(k,.) is a pseudo-random permutation?

(if D is correct, answersA,B,C be interpreted aswrong)

• A. A 3-round cascaded iteration of P(k,(a,b)) = (F(k,a) xor b,a)
• B. A 3-round cascaded iteration of P(k,(a,b)) = (a,F(k,a) xor b)
• C. A 3-round cascaded iteration of P(k,(a,b)) = (b,k xor a)
• D. All of the above