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Impossible Differential Cryptanalysis
In cryptography, impossible differential cryptanalysis is a form of differential cryptanalysis for block ciphers. While ordinary differential cryptanalysis tracks differences that propagate through the cipher with greater than expected probability, impossible differential cryptanalysis exploits differences that are impossible (having probability 0) at some intermediate state of the cipher algorithm. Lars Knudsen appears to be the first to use a form of this attack, in the 1998 paper where he introduced his AES candidate, DEAL. The first presentation to attract the attention of the cryptographic community was later the same year at the rump session of CRYPTO '98, in which Eli Biham, Alex Biryukov, and Adi Shamir introduced the name "impossible differential" and used the technique to break 4.5 out of 8.5 rounds of IDEA and 31 out of 32 rounds of the NSA-designed cipher Skipjack. This development led cryptographer Bruce Schneier to speculate that the NSA had no previous knowledge of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptography
Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), adversarial behavior. More generally, cryptography is about constructing and analyzing Communication protocol, protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, information security, electrical engineering, digital signal processing, physics, and others. Core concepts related to information security (confidentiality, data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, Smart card#EMV, chip-based payment cards, digital currencies, password, computer passwords, and military communications. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skipjack (cipher)
In cryptography, Skipjack is a block cipher—an algorithm for encryption—developed by the United States, U.S. National Security Agency (NSA). Initially Classified information, classified, it was originally intended for use in the controversial Clipper chip. Subsequently, the algorithm was declassified. History of Skipjack Skipjack was proposed as the encryption algorithm in a US government-sponsored scheme of key escrow, and the cipher was provided for use in the Clipper chip, implemented in tamper resistance, tamperproof hardware. Skipjack is used only for encryption; the key escrow is achieved through the use of a separate mechanism known as the Clipper chip, Law Enforcement Access Field (LEAF). The algorithm was initially secret, and was regarded with considerable suspicion by many for that reason. It was classified information, declassified on 24 June 1998, shortly after its basic design principle had been discovered independently by the public cryptography community. To ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XTEA
In cryptography, XTEA (eXtended TEA) is a block cipher designed to correct weaknesses in TEA. The cipher's designers were David Wheeler and Roger Needham of the Cambridge Computer Laboratory, and the algorithm was presented in an unpublished technical report in 1997 (Needham and Wheeler, 1997). It is not subject to any patents. Like TEA, XTEA is a 64-bit block Feistel cipher with a 128-bit key and a suggested 64 rounds. Several differences from TEA are apparent, including a somewhat more complex key-schedule and a rearrangement of the shifts, XORs, and additions. Implementations This standard C source code, adapted from the reference code released into the public domain by David Wheeler and Roger Needham, encrypts and decrypts using XTEA: #include /* take 64 bits of data in v and v and 128 bits of key - key */ void encipher(unsigned int num_rounds, uint32_t v uint32_t const key void decipher(unsigned int num_rounds, uint32_t v uint32_t const key The changes fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiny Encryption Algorithm
In cryptography, the Tiny Encryption Algorithm (TEA) is a block cipher notable for its simplicity of description and implementation, typically a few lines of code. It was designed by David Wheeler (computer scientist), David Wheeler and Roger Needham of the Cambridge University Computer Laboratory, Cambridge Computer Laboratory; it was first presented at the Fast Software Encryption workshop in Leuven in 1994, and first published in the proceedings of that workshop. The cipher is not subject to any patents. Properties TEA operates on two 32-bit unsigned integers (could be derived from a 64-bit data block size (cryptography), block) and uses a 128-bit key (cryptography), key. It has a Feistel network, Feistel structure with a suggested 64 rounds, typically implemented in pairs termed ''cycles''. It has an extremely simple key schedule, mixing all of the key material in exactly the same way for each cycle. Different multiples of a magic number (programming), magic constant are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hierocrypt-3
In cryptography, Hierocrypt-L1 and Hierocrypt-3 are block ciphers created by Toshiba in 2000. They were submitted to the NESSIE project, but were not selected. Both algorithms were among the cryptographic techniques recommended for Japanese government use by CRYPTREC in 2003, however, both have been dropped to "candidate" by CRYPTREC revision in 2013. The Hierocrypt ciphers are very similar, differing mainly in block size: 64 bits for Hierocrypt-L1, 128 bits for Hierocrypt-3. Hierocrypt-L1's key size is 128 bits, while Hierocrypt-3 can use keys of 128, 192, or 256 bits. The number of rounds of encryption also varies: Hierocrypt-L1 uses 6.5 rounds, and Hierocrypt-3 uses 6.5, 7.5, or 8.5, depending on the key size. The Hierocrypt ciphers use a nested substitution–permutation network (SPN) structure. Each round consists of parallel applications of a transformation called the ''XS-box'', followed by a linear diffusion operation. The final half-round replaces the diffusion with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zodiac (cipher)
In cryptography, Zodiac is a block cipher designed in 2000 by Chang-Hyi Lee for the Korean firm SoftForum. Zodiac uses a 16-round Feistel network structure with key whitening. The round function uses only XORs and S-box lookups. There are two 8×8-bit S-boxes: one based on the discrete exponentiation 45''x'' as in SAFER, the other using the multiplicative inverse in the finite field GF(28), as introduced by SHARK. Zodiac is theoretically vulnerable to impossible differential cryptanalysis In cryptography, impossible differential cryptanalysis is a form of differential cryptanalysis for block ciphers. While ordinary differential cryptanalysis tracks differences that propagate through the cipher with greater than expected probability, ..., which can recover a 128-bit key in 2119 encryptions. References * * Further reading * * Broken block ciphers Feistel ciphers {{crypto-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CRYPTON
In cryptography, CRYPTON is a symmetric block cipher submitted as a candidate for the Advanced Encryption Standard (AES). It is very efficient in hardware implementations and was designed by Chae Hoon Lim of Future Systems Inc. The CRYPTON algorithm processes blocks of 128 bits in the form of 4×4 byte arrays. The round transformation consists of four steps: byte-wise substitution, column-wise bit permutation, column-to-row transposition and finally key addition. CRYPTON uses 12 rounds of this encryption process. Due to the algorithm's nature, the decryption process can be made identical to the encryption process using a different key. See also * AES process The Advanced Encryption Standard (AES), the symmetric block cipher ratified as a standard by National Institute of Standards and Technology of the United States (NIST), was chosen using a process lasting from 1997 to 2000 that was markedly more ... External links Hardware Design and Performance Estimation of The 128-b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rijndael
The Advanced Encryption Standard (AES), also known by its original name Rijndael (), is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a variant of the Rijndael block cipher developed by two Belgian cryptographers, Joan Daemen and Vincent Rijmen, who submitted a proposal to NIST during the AES selection process. Rijndael is a family of ciphers with different key and block sizes. For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits. AES has been adopted by the U.S. government. It supersedes the Data Encryption Standard (DES), which was published in 1977. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data. In the United States, AES was announced by the NIST as U.S. FIPS PUB 197 (FIPS 197) on Novem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twofish
In cryptography, Twofish is a symmetric key block cipher with a block size of 128 bits and key sizes up to 256 bits. It was one of the five finalists of the Advanced Encryption Standard contest, but it was not selected for standardization. Twofish is related to the earlier block cipher Blowfish. Twofish's distinctive features are the use of pre-computed key-dependent S-boxes, and a relatively complex key schedule. One half of an n-bit key is used as the actual encryption key and the other half of the n-bit key is used to modify the encryption algorithm (key-dependent S-boxes). Twofish borrows some elements from other designs; for example, the pseudo-Hadamard transform (PHT) from the SAFER family of ciphers. Twofish has a Feistel structure like DES. Twofish also employs a Maximum Distance Separable matrix. When it was introduced in 1998, Twofish was slightly slower than Rijndael (the chosen algorithm for Advanced Encryption Standard) for 128-bit keys, but somewhat faster ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MARS (cryptography)
MARS is a block cipher that was IBM's submission to the Advanced Encryption Standard process. MARS was selected as an AES finalist in August 1999, after the AES2 conference in March 1999, where it was voted as the fifth and last finalist algorithm. The MARS design team included Don Coppersmith, who had been involved in the creation of the previous Data Encryption Standard (DES) twenty years earlier. The project was specifically designed to resist future advances in cryptography by adopting a layered, compartmentalized approach. IBM's official report stated that MARS and Serpent were the only two finalists to implement any form of safety net with regard to would-be advances in cryptographic mathematics. The Twofish team made a similar statement about its cipher. MARS has a 128-bit block size and a variable key size of between 128 and 448 bits (in 32-bit increments). Unlike most block ciphers, MARS has a heterogeneous structure: several rounds of a cryptographic core are "ja ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serpent (cipher)
Serpent is a symmetric key block cipher that was a finalist in the Advanced Encryption Standard process, Advanced Encryption Standard (AES) contest, in which it ranked second to Rijndael. Serpent was designed by Ross J. Anderson, Ross Anderson, Eli Biham, and Lars Knudsen. Like other Advanced Encryption Standard, AES submissions, Serpent has a block size (cryptography), block size of 128 bits and supports a key size of 128, 192, or 256 bits. The cipher is a 32-round substitution–permutation network operating on a block of four 32-bit Word (computer architecture), words. Each round applies one of eight 4-bit to 4-bit S-boxes 32 times in parallel. Serpent was designed so that all operations can be executed in parallel computing, parallel, using 32 bit slices. This maximizes parallelism but also allows use of the extensive cryptanalysis work performed on Data Encryption Standard, DES. Serpent took a conservative approach to security, opting for a large security margin: the design ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
