Mitsubishi Electric Corp. has developed new secret-key cryptosystem MISTY1 and MISTY2, which are ciphers with 128-bit key and 64-bit data block. They are provably secure against differential and linear cryptanalysis,and also fast on software implementations as well as on hardware platforms. Using ciphers on wide-area networks requires a method to maintain security as long as its encryption key (password commonly shared by a sender and a receiver) is kept secret, even if the mechanism of the encryption is made public. However,possibilities of unauthorized access will increase when the encryption mechanism is made public. In fact,several encryption algorithms, whose specifications were made public,have been compelled to make specification changes, and to sacrifice their encryption speed in return for an increased cipher strength to protect against recent decoding methods. This is why an encryption system whose security against these decoding method is strictly evaluated at the design stage has become necessary. Since announcing its linear cryptanalysis,Mitsubishi Electric has been making efforts to develop encryption technology backed by adequate security. In January 1994, Mitsubishi Electric performed the first successful experiment to decode the Data Encryption Standard (DES), an American standard commercial encryption system, to quantitatively evaluate its strength using this linear cryptanalysis. Using this evaluation technology, Mitsubishi Electric has developed an encryption algorithm that provides sufficient security and achieves high speed encryption. ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com