Biryukov, Alex; Nakahara, Jorge Jr.; Preneel, Bart; Vandewalle, Joos, “New Weak-Key Classes of IDEA”, Information and Communications Security, 4th International Conference, ICICS 2002, Lecture Notes in Computer Science 2513: 315–326, http://www.cosic.esat.kuleuven.be/publications/article-189.pdf, "While the zero-one weak keys problem of IDEA can be corrected just by XORing a fixed constant to all the keys (one such constant may be 0DAEx as suggested in [4]) the problem with the runs of ones may still remain and will require complete redesign of the IDEA key schedule."