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RC4
In cryptography, RC4 (Rivest Cipher 4, also known as ARC4 or ARCFOUR, meaning Alleged RC4, see below) is a stream cipher. While it is remarkable for its simplicity and speed in software, multiple vulnerabilities have been discovered in RC4, rendering it insecure. It is especially vulnerable when the beginning of the output keystream is not discarded, or when nonrandom or related keys are used. Particularly problematic uses of RC4 have led to very insecure protocols such as WEP. , there is speculation that some state cryptologic agencies may possess the capability to break RC4 when used in the TLS protocol. IETF has published RFC 7465 to prohibit the use of RC4 in TLS; Mozilla and Microsoft have issued similar recommendations. A number of attempts have been made to strengthen RC4, notably Spritz, RC4A, VMPC, and RC4+. History RC4 was designed by Ron Rivest of RSA Security in 1987. While it is officially termed "Rivest Cipher 4", the RC acronym is alternatively understood to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secure Sockets Layer
Transport Layer Security (TLS) is a cryptographic protocol designed to provide communications security over a computer network, such as the Internet. The protocol is widely used in applications such as email, instant messaging, and voice over IP, but its use in securing HTTPS remains the most publicly visible. The TLS protocol aims primarily to provide security, including privacy (confidentiality), integrity, and authenticity through the use of cryptography, such as the use of certificates, between two or more communicating computer applications. It runs in the presentation layer and is itself composed of two layers: the TLS record and the TLS handshake protocols. The closely related Datagram Transport Layer Security (DTLS) is a communications protocol that provides security to datagram-based applications. In technical writing, references to "(D)TLS" are often seen when it applies to both versions. TLS is a proposed Internet Engineering Task Force (IETF) standard, first def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transport Layer Security
Transport Layer Security (TLS) is a cryptographic protocol designed to provide communications security over a computer network, such as the Internet. The protocol is widely used in applications such as email, instant messaging, and voice over IP, but its use in securing HTTPS remains the most publicly visible. The TLS protocol aims primarily to provide security, including privacy (confidentiality), integrity, and authenticity through the use of cryptography, such as the use of certificates, between two or more communicating computer applications. It runs in the presentation layer and is itself composed of two layers: the TLS record and the TLS handshake protocols. The closely related Datagram Transport Layer Security (DTLS) is a communications protocol that provides security to datagram-based applications. In technical writing, references to "(D)TLS" are often seen when it applies to both versions. TLS is a proposed Internet Engineering Task Force (IETF) standard, fir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wired Equivalent Privacy
Wired Equivalent Privacy (WEP) is an obsolete, and insecure security algorithm for 802.11 wireless networks. It was introduced as part of the original IEEE 802.11 standard ratified in 1997. The intention was to provide a level of security and privacy comparable to that of a traditional wired network. WEP, recognizable by its key of 10 or 26 hexadecimal digits (40 or 104 bits), was at one time widely used, and was often the first security choice presented to users by router configuration tools. After a severe design flaw in the algorithm was disclosed in 2001, WEP was no longer considered a secure method of wireless connection; however, in the vast majority of cases, Wi-Fi hardware devices relying on WEP security could not be upgraded to secure operation. Some of WEP's design flaws were addressed in WEP2, but it also proved insecure, and never saw wide adoption or standardization. In 2003, the Wi-Fi Alliance announced that WEP and WEP2 had been superseded by Wi-Fi Protected Acc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Distinguishing Attack
In cryptography, a distinguishing attack is any form of cryptanalysis on data encrypted by a cipher that allows an attacker to distinguish the encrypted data from random data. Modern symmetric-key ciphers are specifically designed to be immune to such an attack. In other words, modern encryption schemes are pseudorandom permutations and are designed to have ciphertext indistinguishability. If an algorithm is found that can distinguish the output from random faster than a brute force search, then that is considered a break of the cipher. A similar concept is the known-key distinguishing attack, whereby an attacker knows the key and can find a structural property in the cipher, where the transformation from plaintext to ciphertext is not random. Overview To prove that a cryptographic function is safe, it is often compared to a random oracle. If a function were a random oracle, then an attacker is not able to predict any of the output of the function. If a function is distinguishable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variably Modified Permutation Composition
VMPC (Variably Modified Permutation Composition) for cryptography is a stream cipher similar to the well known and popular cipher RC4 designed by Ron Rivest. It was designed by Bartosz Żółtak, presented in 2004 at the Fast Software Encryption conference. VMPC is a modification of the RC4 cipher. (originally presented at FSE 2006 conference) The core of the cipher is the VMPC function, a transformation of ''n''-element permutations defined as: for x from 0 to n-1: g(x) = VMPC(f)(x) = f(f(f(x))+1) The function was designed such that inverting it, i.e. obtaining from , would be a complex problem. According to computer simulations the average number of operations required to recover from for a 16-element permutation is about 211; for 64-element permutation, about 253; and for a 256-element permutation, about 2260. In 2006 at Cambridge University, Kamil Kulesza investigated the problem of inverting VMPC and concluded "results indicate that VMPC is not a good candidate for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ron Rivest
Ronald Linn Rivest (; born May 6, 1947) is an American cryptographer and computer scientist whose work has spanned the fields of algorithms and combinatorics, cryptography, machine learning, and election integrity. He is an Institute Professor at the Massachusetts Institute of Technology (MIT), and a member of MIT's Department of Electrical Engineering and Computer Science and its Computer Science and Artificial Intelligence Laboratory. Along with Adi Shamir and Len Adleman, Rivest is one of the inventors of the RSA algorithm. He is also the inventor of the symmetric key encryption algorithms RC2, RC4, and RC5, and co-inventor of RC6. (''RC'' stands for "Rivest Cipher".) He also devised the MD2, MD4, MD5 and MD6 cryptographic hash functions. Education Rivest earned a bachelor's degree in mathematics from Yale University in 1969, and a Ph.D. degree in computer science from Stanford University in 1974 for research supervised by Robert W. Floyd. Career At MIT, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wi-Fi Protected Access
Wi-Fi Protected Access (WPA) (Wireless Protected Access), Wi-Fi Protected Access 2 (WPA2), and Wi-Fi Protected Access 3 (WPA3) are the three security certification programs developed after 2000 by the Wi-Fi Alliance to secure wireless computer networks. The Alliance defined these in response to serious weaknesses researchers had found in the previous system, Wired Equivalent Privacy (WEP). WPA (sometimes referred to as the TKIP standard) became available in 2003. The Wi-Fi Alliance intended it as an intermediate measure in anticipation of the availability of the more secure and complex WPA2, which became available in 2004 and is a common shorthand for the full IEEE 802.11i (or IEEE 802.11i-2004) standard. In January 2018, the Wi-Fi Alliance announced the release of WPA3, which has several security improvements over WPA2. As of 2023, most computers that connect to a wireless network have support for using WPA, WPA2, or WPA3. All versions thereof, at least as implemented throu ... [...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] |
Cypherpunk
A cypherpunk is one who advocates the widespread use of strong cryptography and privacy-enhancing technologies as a means of effecting social and political change. The cypherpunk movement originated in the late 1980s and gained traction with the establishment of the "Cypherpunks" electronic mailing list in 1992, where informal groups of activists, technologists, and cryptographers discussed strategies to enhance individual privacy and resist state or corporate surveillance. Deeply libertarian in philosophy, the movement is rooted in principles of decentralization, individual autonomy, and freedom from centralized authority. Its influence on society extends to the development of technologies that have reshaped global finance, communication, and privacy practices, such as the creation of Bitcoin and other cryptocurrencies, which embody cypherpunk ideals of decentralized and censorship-resistant money. The movement has also contributed to the mainstreaming of encryption in every ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert John Jenkins Junior
Robert John Jenkins Junior (born 1966 in Akron, Ohio), also known as Bob Jenkins, is an American computer professional and author of several fast pseudorandom number generators such as ISAAC and hash function A hash function is any Function (mathematics), function that can be used to map data (computing), data of arbitrary size to fixed-size values, though there are some hash functions that support variable-length output. The values returned by a ...s ( Jenkins hash)Bob JenkinsHash Functions and Block Ciphers Accessed on 2009-05-29. References 1966 births Living people People from Akron, Ohio {{compu-bio-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exclusive Or
Exclusive or, exclusive disjunction, exclusive alternation, logical non-equivalence, or logical inequality is a logical operator whose negation is the logical biconditional. With two inputs, XOR is true if and only if the inputs differ (one is true, one is false). With multiple inputs, XOR is true if and only if the number of true inputs is odd. It gains the name "exclusive or" because the meaning of "or" is ambiguous when both operands are true. XOR ''excludes'' that case. Some informal ways of describing XOR are "one or the other but not both", "either one or the other", and "A or B, but not A and B". It is symbolized by the prefix operator J Translated as and by the infix operators XOR (, , or ), EOR, EXOR, \dot, \overline, \underline, , \oplus, \nleftrightarrow, and \not\equiv. Definition The truth table of A\nleftrightarrow B shows that it outputs true whenever the inputs differ: Equivalences, elimination, and introduction Exclusive disjunction essentially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
