Security
Weak keys? NO:
- No equivalent keys, no self-inverse keys, no simple relations
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Differential cryptanalysis: Chosen plaintext attack.
- Use certain differences in P and observe differences in C.
- Assign probabilities to keys.
- Result : Can break 5 rounds with 251 work.
Linear cryptanalysis: Nothing found.
Secret trap doors? Most likely not , the authors have no such interest.