Input (grade 10): In 1996, Serge Vaudenay found a known-plaintext attack requiring 28r + 1 known plaintexts to break, where r is the number of rounds.
Output (grade 10): In 1996, Serge Vaudenay found a known-plaintext attack needing 28r + 1 known plaintexts to break, where r is the number of rounds.