saitamanodoruji : day : 2009/12/30

In cryptography, KASUMI, also termed A5/3 when used in GSM and GEA3 when used in GPRS, is a block cipher used in the confidentiality (f8) and integrity algorithms (f9) for 3GPP mobile communications.

KASUMI was designed by the Security Algorithms Group of Experts (SAGE), part of the European standards body ETSI.[1] Rather than invent a cipher from scratch, SAGE selected an existing algorithm, MISTY1, and optimised it slightly for implementation in hardware. Hence, MISTY1 and KASUMI are very similar — kasumi (霞) is the Japanese word for "mist" — and the cryptanalysis of one is likely to be readily adaptable to the other. KASUMI maintains an efficient implementation in software.

KASUMI has a block size of 64 bits and a key size of 128 bits. It is a Feistel cipher with eight rounds, and like MISTY1 and MISTY2, it has a recursive structure, with subcomponents also having a Feistel-like form.

19: Feistel cipher - Wikipedia, the free encyclopedia,http://en.wikipedia.org/wiki/Feistel_cipher

In cryptography, a Feistel cipher is a symmetric structure used in the construction of block ciphers, named after the German-born physicist and cryptographer Horst Feistel who did pioneering research while working for IBM (USA); it is also commonly known as a Feistel network. A large proportion of block ciphers use the scheme, including the Data Encryption Standard (DES). The Feistel structure has the advantage that encryption and decryption operations are very similar, even identical in some cases, requiring only a reversal of the key schedule. Therefore the size of the code or circuitry required to implement such a cipher is nearly halved.

20: Block cipher - Wikipedia, the free encyclopedia,http://en.wikipedia.org/wiki/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 (for example) a 128-bit block of plaintext as input, and output a corresponding 128-bit block of ciphertext. The exact transformation is controlled using a second input — the secret key. Decryption is similar: the decryption algorithm takes, in this example, a 128-bit block of ciphertext together with the secret key, and yields the original 128-bit block of plaintext.

To encrypt messages longer than the block size (128 bits in the above example), a mode of operation is used.

21: Block cipher modes of operation - Wikipedia, the free encyclopedia,http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation

In cryptography, a block cipher operates on blocks of fixed length, often 64 or 128 bits. Because messages may be of any length, and because encrypting the same plaintext under the same key always produces the same output (as described in the ECB section below), several modes of operation have been invented which allow block ciphers to provide confidentiality for messages of arbitrary length.

22: 3GPP - Wikipedia,http://ja.wikipedia.org/wiki/3GPP

23: 3GPP2 - Wikipedia,http://ja.wikipedia.org/wiki/3GPP2

24: Code That Protects Most Cellphone Calls Is Deciphered - NYTimes.com,http://www.nytimes.com/2009/12/29/technology/29hack.html?_r=1