The security of block ciphers, permutations, hash functions and higher-level constructions is studied by modifying the function until some of its claimed proper

The security of block ciphers, permutations, hash functions and higher-level constructions is studied by modifying the function until some of its claimed properties are invalidated. What is being analyzed is not the actual function. How much changes had to be made and how significant they were is an indication of the security margin of the actual function. In this paper, key recovery requires a made-up mode, or an existing mode, but used incorrectly (nonce reuse with the same key and different messages) 2^43.8 times. In addition, the permutation had to be reduced to 6 rounds. The normal number of rounds is 12, which makes a huge difference. The analysis actually shows that the security margin of the real construction is extremely comfortable.