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Suppose I have a Feistel cipher structure that has $16$ rounds. I come up with $8$ subkeys $k_1,k_2,...,k_8$ to be used for the first $8$ rounds and then assign the rest of the keys so that $k_9=k_8,k_{10}=k_7,...,k_{16}=k_1$.

Since the decryption algorithm is the same as encryption, but we reverse the subkeys, would this make our messages vulnerable given that an attacker had an encryption oracle (takes in plaintext and spits out ciphertext)?

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