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Confusion And Diffusion
In cryptography, confusion and diffusion are two properties of a secure cipher identified by Claude Elwood Shannon, Claude Shannon in his 1945 classified report ''A Mathematical Theory of Cryptography''. These properties, when present, work together to thwart the application of statistics, and other methods of cryptanalysis. Confusion in a symmetric cipher is obscuring the local correlation between the input (plaintext), and output (ciphertext) by varying the application of the Key (cryptography), key to the data, while diffusion is hiding the plaintext statistics by spreading it over a larger area of ciphertext. Although ciphers can be confusion-only (substitution cipher, one-time pad) or diffusion-only (transposition cipher), any "reasonable" block cipher uses both confusion and diffusion. These concepts are also important in the design of cryptographic hash function, cryptographic hash functions, and pseudorandom number generators, where decorrelation of the generated values i ... [...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] |
Substitution–permutation Network
In cryptography, an SP-network, or substitution–permutation network (SPN), is a series of linked mathematical operations used in block cipher algorithms such as AES (Rijndael), 3-Way, Kalyna, Kuznyechik, PRESENT, SAFER, SHARK, and Square. Such a network takes a block of the plaintext and the key as inputs, and applies several alternating ''rounds'' or ''layers'' of substitution boxes (S-boxes) and permutation boxes (P-boxes) to produce the ciphertext block. The S-boxes and P-boxes transform of input bits into output bits. It is common for these transformations to be operations that are efficient to perform in hardware, such as exclusive or (XOR) and bitwise rotation. The key is introduced in each round, usually in the form of " round keys" derived from it. (In some designs, the S-boxes themselves depend on the key.) Decryption is done by simply reversing the process (using the inverses of the S-boxes and P-boxes and applying the round keys in reversed order). Comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round (cryptography)
In cryptography, a round or round function is a basic transformation that is repeated (iteration, iterated) multiple times inside the algorithm. Splitting a large algorithmic function into rounds simplifies both implementation and cryptanalysis. For example, encryption using an oversimplified three-round cipher can be written as C = R_3(R_2(R_1(P))), where is the ciphertext and is the plaintext. Typically, rounds R_1, R_2, ... are implemented using the same function, parameterized by the round constant and, for block ciphers, the ''round key'' from the key schedule. Parameterization is essential to reduce the self-similarity of the cipher, which could lead to slide attacks. Increasing the number of rounds "almost always" protects against differential cryptanalysis, differential and linear cryptanalysis, as for these tools the effort grows exponentially with the number of rounds. However, increasing the number of rounds does not ''always'' make weak ciphers into strong ones, as s ... [...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] |
Wide Trail Strategy
WIDE or Wide may refer to: *Wide (cricket), a type of illegal delivery to a batter *Wide and narrow data, terms used to describe two different presentations for tabular data *WIDE Project, Widely Integrated Distributed Environment *Wide-angle Infinity Display Equipment *WIDE-LP, a radio station (99.1 FM) licensed to Madison, Wisconsin *Women in Development Europe; see * wide (tennis), meaning beyond the sidelines People with the name Wide * Ernst Wide (1888–1950), a Swedish Olympic long-distance runner * Edvin Wide (1896–1996), a Swedish Olympic long-distance runner * Samuel Wide (1861–1918), a Swedish archaeologist See also * * * *Widen Widen is a Municipalities of Switzerland, municipality in the district of Bremgarten (district), Bremgarten in the Cantons of Switzerland, canton of Aargau in Switzerland. History At the end of the 12th century a manor called "Wyda" is mention ... * Width (other) {{Disambiguation, callsign ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BaseKing
In cryptography, BaseKing is a block cipher designed in 1994 by Joan Daemen. It is very closely related to 3-Way, as the two are variants of the same general cipher technique. BaseKing has a block size of 192 bits–twice as long as 3-Way, and notably not a power of two as with most block ciphers. The key length is also 192 bits. BaseKing is an 11-round substitution–permutation network. In Daemen's doctoral dissertation he presented an extensive theory of block cipher design, as well as a rather general cipher algorithm composed of a number of invertible transformations that may be chosen with considerable freedom. He discussed the security of this general scheme against known cryptanalytic attacks, and gave two specific examples of ciphers consisting of particular choices for the variable parameters. These ciphers are 3-Way and BaseKing. BaseKing is susceptible to the same kind of related-key attack In cryptography, a related-key attack is any form of cryptanalysi ... [...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] |
S-box
In cryptography, an S-box (substitution-box) is a basic component of symmetric key algorithms which performs substitution. In block ciphers, they are typically used to obscure the relationship between the key and the ciphertext, thus ensuring Claude Shannon, Shannon's property of confusion and diffusion, confusion. Mathematically, an S-box is a nonlinear vectorial Boolean function. In general, an S-box takes some number of input bits, ''m'', and transforms them into some number of output bits, ''n'', where ''n'' is not necessarily equal to ''m''. An ''m''×''n'' S-box can be implemented as a lookup table with 2''m'' words of ''n'' bits each. Fixed tables are normally used, as in the Data Encryption Standard (DES), but in some ciphers the tables are generated dynamically from the cryptographic key, key (e.g. the Blowfish (cipher), Blowfish and the Twofish encryption algorithms). Example One good example of a fixed table is the S-box from DES (S5), mapping 6-bit input into a 4-bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avalanche Effect
In cryptography, the avalanche effect is the desirable property of cryptographic algorithms, typically block ciphers and cryptographic hash functions, wherein if an input is changed slightly (for example, flipping a single bit), the output changes significantly (e.g., half the output bits flip). In the case of high-quality block ciphers, such a small change in either the key or the plaintext should cause a drastic change in the ciphertext. The actual term was first used by Horst Feistel, although the concept dates back to at least Shannon's ''diffusion''. If a block cipher or cryptographic hash function does not exhibit the avalanche effect to a significant degree, then it has poor randomization, and thus a cryptanalyst can make predictions about the input, being given only the output. This may be sufficient to partially or completely break the algorithm. Thus, the avalanche effect is a desirable condition from the point of view of the designer of the cryptographic algorithm or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetric Key
Symmetric-key algorithms are algorithms for cryptography that use the same Key (cryptography), cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between the two keys. The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link. The requirement that both parties have access to the secret key is one of the main drawbacks of symmetric-key encryption, in comparison to Public key encryption, public-key encryption (also known as asymmetric-key encryption). However, symmetric-key encryption algorithms are usually better for bulk encryption. With exception of the one-time pad they have a smaller key size, which means less storage space and faster transmission. Due to this, asymmetric-key encryption is often used to exchange the secret key for symmetric-key encryption. Types Symmetric-key encryption can us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
