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I'm having some issues finding keys to a Feistel network. The function is unknown but we can have as many plaintexts and their given ciphertexts as we want.

I'm trying to generalize the cryptanalysis of this Feistel network for 10 rounds but I can only get the keys for the first round. Do you have any answers or tips?

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  • $\begingroup$ Thre is no non-linearity here. Just perform an algebraic attack - Set up equations and solve them... $\endgroup$ – kelalaka Apr 7 at 0:03
  • $\begingroup$ @kelalaka Well i'm new in cryptography so can you give me an example because i set up the equations and this doesn't look like solvable one. $\endgroup$ – rollersg Apr 7 at 0:19
  • $\begingroup$ There is here for LFSRs. Same idea. $\endgroup$ – kelalaka Apr 7 at 0:27
  • $\begingroup$ Thx for your help, so with the algebraic attack i only need one plaintext and its ciphertext right ? And beside the algebraic attack, is there any faster way to solve this by using more plaintext and ciphertext ? $\endgroup$ – rollersg Apr 7 at 1:18
  • $\begingroup$ That will depend on the number of equations and variables. $\endgroup$ – kelalaka Apr 7 at 1:22

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