MISTY1
Encyclopedia
In cryptography
, MISTY1 (or MISTY-1) is a block cipher
designed in 1995 by Mitsuru Matsui
and others for Mitsubishi Electric
.
MISTY1 is one of the selected algorithms in the Europe
an NESSIE
project, and has been recommended for Japanese government use by the CRYPTREC
project.
"MISTY" can stand for "Mitsubishi Improved Security Technology", it is also the initials of the researchers involved in its development: Matsui Mitsuru, Ichikawa Tetsuya, Sorimachi Toru, Tokita Toshio, and Yamagishi Atsuhiro.
MISTY1 is covered by patents, although the algorithm is freely available for academic (non-profit) use in RFC 2994.
of 128 bits. MISTY1 has an innovative recursive structure; the round function itself uses a 3-round Feistel network. MISTY1 claims to be provably secure against linear
and differential cryptanalysis
.
s. In 2005, KASUMI was broken, and in 2010 a new paper was published detailing a practical attack on the cipher; see the article for more details.
In the paper "Block Ciphers and Stream Ciphers" by Alex Biryukov
, it is noted that KASUMI, also termed A5/3, is a strengthened version of block cipher MISTY1 running in a Counter mode.
However, in 2010 Dunkelman, Keller, and Shamir showed that KASUMI is not as strong as MISTY1 but interestingly the KASUMI attack will not work against MISTY1.
Cryptography
Cryptography is the practice and study of techniques for secure communication in the presence of third parties...
, MISTY1 (or MISTY-1) is a block cipher
Block cipher
In cryptography, a block cipher is a symmetric key cipher operating on fixed-length groups of bits, called blocks, with an unvarying transformation. A block cipher encryption algorithm might take a 128-bit block of plaintext as input, and output a corresponding 128-bit block of ciphertext...
designed in 1995 by Mitsuru Matsui
Mitsuru Matsui
is a Japanese cryptographer and senior researcher for Mitsubishi Electric Company. While researching error-correcting codes in 1990, Matsui was inspired by Biham and Shamir's differential cryptanalysis, and discovered the technique of linear cryptanalysis, published in 1993. Differential and linear...
and others for Mitsubishi Electric
Mitsubishi Electric
is a multinational electronics and information technology company headquartered in Tokyo, Japan. It is one of the core companies of the Mitsubishi Group....
.
MISTY1 is one of the selected algorithms in the Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an NESSIE
NESSIE
NESSIE was a European research project funded from 2000–2003 to identify secure cryptographic primitives. The project was comparable to the NIST AES process and the Japanese Government-sponsored CRYPTREC project, but with notable differences from both...
project, and has been recommended for Japanese government use by the CRYPTREC
CRYPTREC
CRYPTREC is the Cryptography Research and Evaluation Committees set up by the Japanese Government to evaluate and recommend cryptographic techniques for government and industrial use...
project.
"MISTY" can stand for "Mitsubishi Improved Security Technology", it is also the initials of the researchers involved in its development: Matsui Mitsuru, Ichikawa Tetsuya, Sorimachi Toru, Tokita Toshio, and Yamagishi Atsuhiro.
MISTY1 is covered by patents, although the algorithm is freely available for academic (non-profit) use in RFC 2994.
Security
MISTY1 is a Feistel network with a variable number of rounds (any multiple of 4), though 8 are recommended. The cipher operates on 64-bit blocks and has a key sizeKey size
In cryptography, key size or key length is the size measured in bits of the key used in a cryptographic algorithm . An algorithm's key length is distinct from its cryptographic security, which is a logarithmic measure of the fastest known computational attack on the algorithm, also measured in bits...
of 128 bits. MISTY1 has an innovative recursive structure; the round function itself uses a 3-round Feistel network. MISTY1 claims to be provably secure against linear
Linear cryptanalysis
In cryptography, linear cryptanalysis is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. Attacks have been developed for block ciphers and stream ciphers...
and differential cryptanalysis
Differential cryptanalysis
Differential cryptanalysis is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. In the broadest sense, it is the study of how differences in an input can affect the resultant difference at the output...
.
KASUMI
KASUMI is a successor of the MISTY1 cipher which was supposed to be stronger than MISTY1 and has been adopted as the standard encryption algorithm for European mobile phoneMobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s. In 2005, KASUMI was broken, and in 2010 a new paper was published detailing a practical attack on the cipher; see the article for more details.
In the paper "Block Ciphers and Stream Ciphers" by Alex Biryukov
Alex Biryukov
Alex Biryukov is a cryptographer, currently an assistant professor at the University of Luxembourg. His notable work includes the design of the stream cipher LEX, as well as the cryptanalysis of numerous cryptographic primitives. In 1998, he developed impossible differential cryptanalysis together...
, it is noted that KASUMI, also termed A5/3, is a strengthened version of block cipher MISTY1 running in a Counter mode.
However, in 2010 Dunkelman, Keller, and Shamir showed that KASUMI is not as strong as MISTY1 but interestingly the KASUMI attack will not work against MISTY1.