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Khaled
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# DES security if used a SHA3 function instead of Normal DES function?

I was practicing some python programming and I decided to implement a simple DES encryption function, so i decided to take some shortcuts so instead of DES expansion boxes and s-Boxes i just used a simple keyed SHA3 hash function the input is: 32-bit right side + key(any length I want but I used 128-bit) The first 32-bit of hash are xor-ed with left side to produce ciphertext. So now ignoring that i designed my own crypto and the fact that I used a very simple key schedule function. what are the security advantages of using this hash function instead of normal one (taking in mind that it takes 128-bit key which is greater than 56-bit key of Normal DES), and how it will differ if I used SHA2 (would SHA2 susceptibility to length extension attacks affect the security). lastly what are the advantages of using this method.

Khaled
• 343
• 10