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DFC (cipher)
In cryptography, DFC (Decorrelated Fast Cipher) is a symmetric block cipher which was created in 1998 by a group of researchers from École Normale Supérieure, CNRS, and France Télécom (including Jacques Stern and Serge Vaudenay) and submitted to the AES competition. Like other AES candidates, DFC operates on blocks of 128 bits, using a key of 128, 192, or 256 bits. It uses an 8-round Feistel network. The round function uses a single 6×32-bit S-box, as well as an affine transformation mod 264+13. DFC can actually use a key of any size up to 256 bits; the key schedule uses another 4-round Feistel network to generate a 1024-bit "expanded key". The arbitrary constants, including all entries of the S-box, are derived using the binary expansion of e as a source of "nothing up my sleeve numbers". Soon after DFC's publication, Ian Harvey raised the concern that reduction modulo a 65-bit number was beyond the native capabilities of most platforms, and that careful implementation w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AES Competition
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 open and transparent than its predecessor, the Data Encryption Standard (DES). This process won praise from the open cryptographic community, and helped to increase confidence in the security of the winning algorithm from those who were suspicious of backdoors in the predecessor, DES. A new standard was needed primarily because DES has a relatively small 56-bit key which was becoming vulnerable to brute-force attacks. In addition, the DES was designed primarily for hardware and is relatively slow when implemented in software. While Triple-DES avoids the problem of a small key size, it is very slow even in hardware, it is unsuitable for limited-resource platforms, and it may be affected by potential security issues connected with the (today ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacques Stern
Jacques Stern (born 21 August 1949) is a cryptographer, currently a professor at the École Normale Supérieure. He received the 2006 CNRS Gold medal. His notable work includes the cryptanalysis of numerous encryption and signature schemes, the design of the Pointcheval–Stern signature algorithm, the Naccache–Stern cryptosystem and Naccache–Stern knapsack cryptosystem, and the block ciphers CS-Cipher, DFC, and xmx. He also contributed to the cryptanalysis of the ''SFLASH'' signature scheme. Awards * Knight of the Légion d'honneur recipient * 2005 CNRS Silver Medal The CNRS Silver Medal is a scientific award given every year to about fifteen researchers by the French National Centre for Scientific Research The French National Centre for Scientific Research (french: link=no, Centre national de la recherch ... * IACR Fellow, 2005 * 2006 CNRS Gold medal * 2007 RSA Award for Excellence in Mathematics References External links * Modern cryptographers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E (mathematical Constant)
The number , also known as Euler's number, is a mathematical constant approximately equal to 2.71828 that can be characterized in many ways. It is the base of the natural logarithms. It is the limit of as approaches infinity, an expression that arises in the study of compound interest. It can also be calculated as the sum of the infinite series e = \sum\limits_^ \frac = 1 + \frac + \frac + \frac + \cdots. It is also the unique positive number such that the graph of the function has a slope of 1 at . The (natural) exponential function is the unique function that equals its own derivative and satisfies the equation ; hence one can also define as . The natural logarithm, or logarithm to base , is the inverse function to the natural exponential function. The natural logarithm of a number can be defined directly as the area under the curve between and , in which case is the value of for which this area equals one (see image). There are various other characteriz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fast Software Encryption
Fast or FAST may refer to: * Fast (noun), high speed or velocity * Fast (noun, verb), to practice fasting, abstaining from food and/or water for a certain period of time Acronyms and coded Computing and software * ''Faceted Application of Subject Terminology'', a thesaurus of subject headings * Facilitated Application Specification Techniques, a team-oriented approach for requirement gathering * FAST protocol, an adaptation of the FIX protocol, optimized for streaming * FAST TCP, a TCP congestion avoidance algorithm * FAST and later as Fast Search & Transfer, a Norwegian company focusing on data search technologies * Fatigue Avoidance Scheduling Tool, software to develop work schedules * Features from accelerated segment test, computer vision method for corner detection * Federation Against Software Theft, a UK organization that pursues those who illegally distribute software * Feedback arc set in Tournaments, a computational problem in graph theory * USENIX Conference on File a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PostScript
PostScript (PS) is a page description language in the electronic publishing and desktop publishing realm. It is a dynamically typed, concatenative programming language. It was created at Adobe Systems by John Warnock, Charles Geschke, Doug Brotz, Ed Taft and Bill Paxton from 1982 to 1984. History The concepts of the PostScript language were seeded in 1976 by John Gaffney at Evans & Sutherland, a computer graphics company. At that time Gaffney and John Warnock were developing an interpreter for a large three-dimensional graphics database of New York Harbor. Concurrently, researchers at Xerox PARC had developed the first laser printer and had recognized the need for a standard means of defining page images. In 1975-76 Bob Sproull and William Newman developed the Press format, which was eventually used in the Xerox Star system to drive laser printers. But Press, a data format rather than a language, lacked flexibility, and PARC mounted the Interpress effort to create a succ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henri Gilbert
Henri is an Estonian, Finnish, French, German and Luxembourgish form of the masculine given name Henry. People with this given name ; French noblemen :'' See the 'List of rulers named Henry' for Kings of France named Henri.'' * Henri I de Montmorency (1534–1614), Marshal and Constable of France * Henri I, Duke of Nemours (1572–1632), the son of Jacques of Savoy and Anna d'Este * Henri II, Duke of Nemours (1625–1659), the seventh Duc de Nemours * Henri, Count of Harcourt (1601–1666), French nobleman * Henri, Dauphin of Viennois (1296–1349), bishop of Metz * Henri de Gondi (other) * Henri de La Tour d'Auvergne, Duke of Bouillon (1555–1623), member of the powerful House of La Tour d'Auvergne * Henri Emmanuel Boileau, baron de Castelnau (1857–1923), French mountain climber * Henri, Grand Duke of Luxembourg (born 1955), the head of state of Luxembourg * Henri de Massue, Earl of Galway, French Huguenot soldier and diplomat, one of the principal commanders of Batt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Don Coppersmith
Don Coppersmith (born 1950) is a cryptographer and mathematician. He was involved in the design of the Data Encryption Standard block cipher at IBM, particularly the design of the S-boxes, strengthening them against differential cryptanalysis. He also improved the quantum Fourier transform discovered by Peter Shor in the same year (1994). He has also worked on algorithms for computing discrete logarithms, the cryptanalysis of RSA, methods for rapid matrix multiplication (see Coppersmith–Winograd algorithm) and IBM's MARS cipher. Don is also a co-designer of the SEAL and Scream ciphers. In 1972, Coppersmith obtained a bachelor's degree in mathematics at the Massachusetts Institute of Technology, and a Masters and Ph.D. in mathematics from Harvard University in 1975 and 1977 respectively. He was a Putnam Fellow each year from 1968–1971, becoming the first four-time Putnam Fellow in history. In 1998, he started ''Ponder This'', an online monthly column on mathematical puz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weak Key
In cryptography, a weak key is a key, which, used with a specific cipher, makes the cipher behave in some undesirable way. Weak keys usually represent a very small fraction of the overall keyspace, which usually means that, if one generates a random key to encrypt a message, weak keys are very unlikely to give rise to a security problem. Nevertheless, it is considered desirable for a cipher to have no weak keys. A cipher with no weak keys is said to have a ''flat'', or ''linear'', key space. Historical origins Virtually all rotor-based cipher machines (from 1925 onwards) have implementation flaws that lead to a substantial number of weak keys being created. Some rotor machines have more problems with weak keys than others, as modern block and stream ciphers do. The first stream cipher machines were also rotor machines and had some of the same problems of weak keys as the more traditional rotor machines. The T52 was one such stream cipher machine that had weak key problems. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chosen-ciphertext Attack
A chosen-ciphertext attack (CCA) is an attack model for cryptanalysis where the cryptanalyst can gather information by obtaining the decryptions of chosen ciphertexts. From these pieces of information the adversary can attempt to recover the hidden secret key used for decryption. For formal definitions of security against chosen-ciphertext attacks, see for example: Michael Luby and Mihir Bellare et al. Introduction A number of otherwise secure schemes can be defeated under chosen-ciphertext attack. For example, the El Gamal cryptosystem is semantic security, semantically secure under chosen-plaintext attack, but this semantic security can be trivially defeated under a chosen-ciphertext attack. Early versions of RSA (algorithm), RSA padding used in the Secure Sockets Layer, SSL protocol were vulnerable to a sophisticated adaptive chosen-ciphertext attack which revealed SSL session keys. Chosen-ciphertext attacks have implications for some self-synchronizing stream ciphers as wel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Linear cryptanalysis is one of the two most widely used attacks on block ciphers; the other being differential cryptanalysis. The discovery is attributed to Mitsuru Matsui, who first applied the technique to the FEAL cipher (Matsui and Yamagishi, 1992). Subsequently, Matsui published an attack on the Data Encryption Standard (DES), eventually leading to the first experimental cryptanalysis of the cipher reported in the open community (Matsui, 1993; 1994). The attack on DES is not generally practical, requiring 247 known plaintexts. A variety of refinements to the attack have been suggested, including using multiple linear approximations or incorporating non-linear expressions, leading to a generalized partitioning cryptanalysis. Evidence of security against linear cryptanalysis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 information input can affect the resultant difference at the output. In the case of a block cipher, it refers to a set of techniques for tracing differences through the network of transformation, discovering where the cipher exhibits non-random behavior, and exploiting such properties to recover the secret key (cryptography key). History The discovery of differential cryptanalysis is generally attributed to Eli Biham and Adi Shamir in the late 1980s, who published a number of attacks against various block ciphers and hash functions, including a theoretical weakness in the Data Encryption Standard (DES). It was noted by Biham and Shamir that DES was surprisingly resistant to differential cryptanalysis but small modifications to the algorithm would make it much mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Provable Security
Provable security refers to any type or level of computer security that can be proved. It is used in different ways by different fields. Usually, this refers to mathematical proofs, which are common in cryptography. In such a proof, the capabilities of the attacker are defined by an adversarial model (also referred to as attacker model): the aim of the proof is to show that the attacker must solve the underlying hard problem in order to break the security of the modelled system. Such a proof generally does not consider side-channel attacks or other implementation-specific attacks, because they are usually impossible to model without implementing the system (and thus, the proof only applies to this implementation). Outside of cryptography, the term is often used in conjunction with secure coding and security by design, both of which can rely on proofs to show the security of a particular approach. As with the cryptographic setting, this involves an attacker model and a model of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
