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Stream Cipher
stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream ( keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, to give a digit of the ciphertext stream. Since encryption of each digit is dependent on the current state of the cipher, it is also known as ''state cipher''. In practice, a digit is typically a bit and the combining operation is an exclusive-or (XOR). The pseudorandom keystream is typically generated serially from a random seed value using digital shift registers. The seed value serves as the cryptographic key for decrypting the ciphertext stream. Stream ciphers represent a different approach to symmetric encryption from block ciphers. Block ciphers operate on large blocks of digits with a fixed, unvarying transformation. This distinction is not always clear-cut: in some modes of operation, a block cipher primitive is used in such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claude E
Claude may refer to: People and fictional characters * Claude (given name), a list of people and fictional characters * Claude (surname), a list of people * Claude Callegari (1962–2021), English Arsenal supporter * Claude Debussy (1862–1918), French composer * Claude Kiambe (born 2003), Congolese-born Dutch singer * Claude Lévi-Strauss (1908–2009), French anthropologist and ethnologist * Claude Lorrain (c. 1600–1682), French landscape painter, draughtsman and etcher traditionally called just "Claude" in English * Claude Makélélé (born 1973), French football manager * Claude McKay (1890–1948), Jamaican-American writer and poet * Claude Monet (1840–1926), French painter * Claude Rains (1889–1967), British-American actor * Claude Shannon (1916–2001), American mathematician, electrical engineer and computer scientist * Madame Claude (1923–2015), French brothel keeper Fernande Grudet Places * Claude, Texas, a city * Claude, West Virginia, an unincorporated commu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shrinking Generator
In cryptography, the shrinking generator is a form of pseudorandom number generator intended to be used in a stream cipher. It was published in Crypto 1993 by Don Coppersmith, Hugo Krawczyk and Yishay Mansour. The shrinking generator uses two linear-feedback shift registers. One, called the sequence, generates output bits, while the other, called the sequence, controls their output. Both and are clocked; if the bit is 1, then the bit is output; if the bit is 0, the bit is discarded, nothing is output, and the registers are clocked again. This has the disadvantage that the generator's output rate varies irregularly, and in a way that hints at the state of S; this problem can be overcome by buffering the output. The random sequence generated by LFSR can not guarantee the unpredictability in secure system and various methods have been proposed to improve its randomness Despite this simplicity, there are currently no known attacks better than exhaustive search when the fee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternating Step Generator
In cryptography, an alternating step generator (ASG) is a cryptographic pseudorandom number generator used in stream ciphers, based on three linear-feedback shift registers. Its output is a combination of two LFSRs which are stepped (clocked) in an alternating fashion, depending on the output of a third LFSR. The design was published in 1987 and patented in 1989 by C. G. Günther. Overview Linear-feedback shift registers (LFSRs) are, statistically speaking, excellent pseudorandom generators, with good distribution and simple implementation. However, they cannot be used as-is because their output can be predicted easily. An ASG comprises three linear-feedback shift registers, which we will call LFSR0, LFSR1 and LFSR2 for convenience. The output of one of the registers decides which of the other two is to be used; for instance if LFSR2 outputs a 0, LFSR0 is clocked, and if it outputs a 1, LFSR1 is clocked instead. The output is the exclusive OR of the last bit produced by LFSR0 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stop-and-go Generator , a Korean card game
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A stop-and-go may refer to: * Stop-and-go route, in American football * Stop-go, a penalty in motorsport; see * '' Stop & Go'', a 1973 album by American musician Hamilton Bohannon * Traffic wave See also * Go-Stop Go-Stop (), also called Godori (, after the winning move in the game) is a Korean Card game#Fishing games, fishing card game played with a Hanafuda, Hwatu () deck. The game can be called Matgo () when only two players are playing. The game is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Correlation Attack
Correlation attacks are a class of cryptographic known-plaintext attacks for breaking stream ciphers whose keystreams are generated by combining the output of several linear-feedback shift registers (LFSRs) using a Boolean function. Correlation attacks exploit a statistical weakness that arises from the specific Boolean function chosen for the keystream. While some Boolean functions are vulnerable to correlation attacks, stream ciphers generated using such functions are not inherently insecure. Explanation Correlation attacks become possible when a significant correlation exists between the output state of an individual LFSR in the keystream generator and the output of the Boolean function that combines the output states of all the LFSRs. These attacks are employed in combination with partial knowledge of the keystream, which is derived from partial knowledge of the plaintext. The two are then compared using an XOR logic gate. This vulnerability allows an attacker to brute-force ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boolean Function
In mathematics, a Boolean function is a function whose arguments and result assume values from a two-element set (usually , or ). Alternative names are switching function, used especially in older computer science literature, and truth function (or logical function), used in logic. Boolean functions are the subject of Boolean algebra and switching theory. A Boolean function takes the form f:\^k \to \, where \ is known as the Boolean domain and k is a non-negative integer called the arity of the function. In the case where k=0, the function is a constant element of \. A Boolean function with multiple outputs, f:\^k \to \^m with m>1 is a vectorial or ''vector-valued'' Boolean function (an S-box in symmetric cryptography). There are 2^ different Boolean functions with k arguments; equal to the number of different truth tables with 2^k entries. Every k-ary Boolean function can be expressed as a propositional formula in k variables x_1,...,x_k, and two propositional formulas a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear-feedback Shift Register
In computing, a linear-feedback shift register (LFSR) is a shift register whose input bit is a Linear#Boolean functions, linear function of its previous state. The most commonly used linear function of single bits is exclusive-or (XOR). Thus, an LFSR is most often a shift register whose input bit is driven by the XOR of some bits of the overall shift register value. The initial value of the LFSR is called the seed, and because the operation of the register is deterministic, the stream of values produced by the register is completely determined by its current (or previous) state. Likewise, because the register has a finite number of possible states, it must eventually enter a repeating cycle. However, an LFSR with a Primitive polynomial (field theory), well-chosen feedback function can produce a sequence of bits that appears random and has a Maximal length sequence, very long cycle. Applications of LFSRs include generating Pseudorandomness, pseudo-random numbers, Pseudorandom n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Cipher Modes Of Operation
In cryptography, a block cipher mode of operation is an algorithm that uses a block cipher to provide information security such as confidentiality or authenticity. A block cipher by itself is only suitable for the secure cryptographic transformation (encryption or decryption) of one fixed-length group of bits called a block. A mode of operation describes how to repeatedly apply a cipher's single-block operation to securely transform amounts of data larger than a block. Most modes require a unique binary sequence, often called an initialization vector (IV), for each encryption operation. The IV must be non-repeating, and for some modes must also be random. The initialization vector is used to ensure that distinct ciphertexts are produced even when the same plaintext is encrypted multiple times independently with the same key. Block ciphers may be capable of operating on more than one block size, but during transformation the block size is always fixed. Block cipher mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cipher Feedback
In cryptography, a block cipher mode of operation is an algorithm that uses a block cipher to provide information security such as confidentiality or authenticity. A block cipher by itself is only suitable for the secure cryptographic transformation (encryption or decryption) of one fixed-length group of bits called a block. A mode of operation describes how to repeatedly apply a cipher's single-block operation to securely transform amounts of data larger than a block. Most modes require a unique binary sequence, often called an initialization vector (IV), for each encryption operation. The IV must be non-repeating, and for some modes must also be random. The initialization vector is used to ensure that distinct ciphertexts are produced even when the same plaintext is encrypted multiple times independently with the same key. Block ciphers may be capable of operating on more than one block size, but during transformation the block size is always fixed. Block cipher modes o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attack (computing)
A cyberattack (or cyber attack) occurs when there is an unauthorized action against computer infrastructure that compromises the confidentiality, integrity, or availability of its content. The rising dependence on increasingly complex and interconnected computer systems in most domains of life is the main factor that causes vulnerability to cyberattacks, since virtually all computer systems have bugs that can be exploited by attackers. Although it is impossible or impractical to create a perfectly secure system, there are many defense mechanisms that can make a system more difficult to attack, making information security a field of rapidly increasing importance in the world today. Perpetrators of a cyberattack can be criminals, hacktivists, or states. They attempt to find weaknesses in a system, exploit them and create malware to carry out their goals, and deliver it to the targeted system. Once installed, the malware can have a variety of effects depending on its purpose. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
