Mitsuru Matsui
Japanese cryptographer who developed linear cryptanalysis and designed the MISTY1 block cipher.
Matsui presented linear cryptanalysis of DES at Eurocrypt in 1993. The following year he used it for the first experimental break of DES, a computation that took roughly 50 days on around a dozen workstations. The method looks for linear relations between bits of plaintext, ciphertext and key, and it has since become a standard test for new ciphers.
Matsui also designed MISTY1, published in 1997 and built to resist both linear and differential cryptanalysis.