Civil Rights
Movements, leaders, victories and the continuing fight for equality.
q2K BHP
Black History Portal
THE BHP WIRE —
HIDDEN TRUTHS
What's New!
Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
Mansa Musa was the ruler of the Mali Empire in West Africa. Details recorded here should be sourced; unknown information is left blank.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
In cryptography, deniable authentication is message authentication between a set of participants where the participants themselves can be confident in the authenticity of the messages, but it cannot be proved to a third party after the event.[1][2][3]
In practice, deniable authentication between two parties can be achieved through the use of message authentication codes (MACs) by making sure that if an attacker is able to decrypt the messages, they would also know the MAC key as part of the protocol, and would thus be able to forge authentic-looking messages.[4] For example, in the Off-the-Record Messaging (OTR) protocol, MAC keys are derived from the asymmetric decryption key through a cryptographic hash function. In addition to that, the OTR protocol also reveals used MAC keys as part of the next message, after they have already been used to authenticate previously received messages, and they are not used again.[5]
{{cite journal}}: Cite uses deprecated parameter |citeseerx= (help) (Download 2005 preprint version)
 | This cryptography-related article is a stub. You can help Wikipedia by adding missing information. |
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
In cryptography, deniable authentication is message authentication between a set of participants where the participants themselves can be confident in the authenticity of the messages, but it cannot be proved to a third party after the event. In practice, deniable authentication between two parties can be achieved through the use of message authentication codes (MACs) by making sure that if an attacker is able to decrypt the messages, they would also know the MAC key as part of the protocol, and would thus be able to forge authentic-looking messages. For example, in the Off-the-Record Messaging (OTR) protocol, MAC keys are derived from the asymmetric decryption key through a cryptographic hash function. In addition to that, the OTR protocol also reveals used MAC keys as part of the next message, after they have already been used to authenticate previously received messages, and they are not used again.
A cryptographic hash function (CHF) is a hash algorithm (a map of an arbitrary binary string to a binary string with a fixed size of n {\displaystyle n} bits) that has special properties desirable for cryptographic applications. Hashing is a one-directional mathematical operation which is quick to calculate, yet hard to reverse. Common uses include password storage and digital signatures. Even a small change in the input results in a very different hash, meaning that it functions as an efficient and consistent way to check if two copies of data or software match. Typically, the operation works on a block of input data; the hash output is then hashed with the next block, creating a new hash reflecting everything to that point; this action is repeated until the hash reflects everything through the final block. More technically: the probability of a particular n {\displaystyle n} -bit output result (hash value) for a random input string ("message") is 2 − n {\displaystyle 2^{-n}} (as for any good hash), so the hash value can be used as a representative of the message; finding an input string that matches a given hash value (a pre-image) is infeasible, assuming all input strings are equally likely. The resistance to such search is quantified as security strength: a cryptographic hash with n {\displaystyle n} bits of hash value is expected to have a preimage resistance strength of n {\displaystyle n} bits, unless the space of possible input values is significantly smaller than 2 n {\displaystyle 2^{n}} (a practical example can be found in § Attacks on hashed passwords); a second preimage resistance strength, with the same expectations, refers to a similar problem of finding a second message that matches the given hash value when one message is already known; finding any pair of different messages that yield the same hash value (a collision) is also infeasible: a cryptographic hash is expected to have a collision resistance strength of n / 2 {\displaystyle n/2} bits (lower because of the birthday paradox). Cryptographic hash functions have many information-security applications, notably in digital signatures, message authentication codes (MACs), and other forms of authentication. They can also be used as ordinary hash functions, to index data in hash tables, for fingerprinting, to detect duplicate data or uniquely identify files, and as checksums to detect accidental data corruption. Indeed, in information-security contexts, cryptographic hash values are sometimes called (digital) fingerprints, checksums, (message) digests, or just hash values, even though all these terms stand for more general functions with rather different properties and purposes. Non-cryptographic hash functions are used in hash tables and to detect accidental errors; their constructions frequently provide no resistance to a deliberate attack. For example, a denial-of-service attack on hash tables is possible if the collisions are easy to find, as in the case of linear cyclic redundancy check (CRC) functions.
In cryptography, a sponge function or sponge construction is any of a class of algorithms with finite internal state that take an input bit stream of any length and produce an output bit stream of any desired length. Sponge functions have both theoretical and practical uses. They can be used to model or implement many cryptographic primitives, including cryptographic hashes, message authentication codes, mask generation functions, stream ciphers, pseudo-random number generators, and authenticated encryption.
ISO/IEC 9797-1 Information technology – Security techniques – Message Authentication Codes (MACs) – Part 1: Mechanisms using a block cipher is an international standard that defines methods for calculating a message authentication code (MAC) over data. Rather than defining one specific algorithm, the standard defines a general model from which a variety of specific algorithms can be constructed. The model is based on a block cipher with a secret symmetric key. Because the standard describes a model rather than a specific algorithm, users of the standard must specify all of the particular options and parameter to be used, to ensure unambiguous MAC calculation.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Mae Jemison, aboard Space Shuttle Endeavour in 1992.
