Four round Feistel network using pseudo random round function

Mary

10/14/22, 2:48 PM

I am solving a four-round Feistel network using pseudo-random round function is a strong pseudo-random function for security against adversaries, but I don't understand that how to solve I know 3 round.

Can you please explain the procedure?

I am assuming ${F : \{0,1\}^λ × \{0,1\}^λ → \{0,1\}^λ }$ be a secure PRF with in = out = λ, and define ${F^∗ : \{0,1\}^{4λ} × \{0,1\}^{2λ} → \{0,1\}^{2λ}}$

Then ${F^∗ }$is a secure strong PRP.

100

0 + 2

feistel-network

pseudo-random-function

pseudo-random-permutation

Fractalice

10/18/22, 8:56 AM

How $F^*$ is defined? Why it maps $4\lambda+2\lambda$ bits into $2\lambda$ bits? Feistel network would map $2\lambda$ bits to $2\lambda$ bits.

Irad Nuriel

10/23/22, 5:39 AM

@Fractalice I think $F^*$ is a 4 rounds feistel network with $F$ as the round function, the $2λ$ is the input to the feistel network, and the $4λ$ is for round keys or something

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Four round Feistel network using pseudo random round function

TH: เครือข่าย Feistel สี่รอบโดยใช้ฟังก์ชันรอบสุ่มหลอก

RO: Rețeaua Feistel cu patru runde folosind funcția rotundă pseudo-aleatorie

RU: Сеть Фейстеля с четырьмя раундами, использующая функцию псевдослучайного раунда

VI: Mạng Feistel bốn vòng sử dụng chức năng vòng giả ngẫu nhiên

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