How to Construct Pseudo-Random Permutations from Pseudo-Random Functions (Abstract)

Let F n be the set of all functions from n bits to n bits. Let f n specify for each key k of a given length a function f k n ∈ F n . We say f n is pseudorandom if the following two properties hold: (1) Given a key k and an input α of length n, the time to evaluate f k n (α) is polynomial in n. (2) If a random key k is chosen, f k n “looks like” a random function chosen from F n to any algorithm which is allowed to evaluate f k n at polynomial in n input values.