Akelarre is a 128-bit block cipher with a variable key-length which must be some multiple of 64 bits.
The round function of Akelarre is similar to IDEA in structure.
After the successful cryptanalysis of Akelarre, its designers responded with an updated variant called Ake98.
In 2004, Jorge Nakahara, Jr. and Daniel Santana de Freitas found large classes of weak keys for Ake98.
These weak keys allow a cryptanalysis faster than exhaustive search using only 71 known plaintexts, for up to 11.5 rounds of Ake98.