Questions tagged [luby-rackoff]
A Luby-Rackoff cipher is a Feistel cipher where in each round the nonlinear function used is assumed to be chosen uniformly at random from the set of all such functions. These ciphers are mainly of theoretical interest.
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Luby-Rackoff theorem confusion
The Luby-Rackoff theorem states that if a round function is a secure pseudorandom function (PRF)
then 3 rounds are sufficient to make the block cipher a pseudorandom permutation (PRP).
PRPs are ...
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Need for 3 rounds in Luby Rackoff theorem
I get that using Feistel network we can create a secure PRP from a secure PRF (in 3 rounds according to theorem).
My question is why not just 2 rounds of Feistel network is sufficient. Is it that ...