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.
In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
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
 | This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (August 2017) |
In cryptography, mod n cryptanalysis is an attack applicable to block and stream ciphers. It is a form of partitioning cryptanalysis that exploits unevenness in how the cipher operates over equivalence classes (congruence classes) modulo n. The method was first suggested in 1999 by John Kelsey, Bruce Schneier, and David Wagner and applied to RC5P (a variant of RC5) and M6 (a family of block ciphers used in the FireWire standard). These attacks used the properties of binary addition and bit rotation modulo a Fermat prime.
For RC5P, analysis was conducted modulo 3. It was observed that the operations in the cipher (rotation and addition, both on 32-bit words) were somewhat biased over congruence classes mod 3. To illustrate the approach, consider left rotation by a single bit:
Then, because
it follows that
Thus left rotation by a single bit has a simple description modulo 3. Analysis of other operations (data dependent rotation and modular addition) reveals similar, notable biases. Although there are some theoretical problems analysing the operations in combination, the bias can be detected experimentally for the entire cipher. In (Kelsey et al., 1999), experiments were conducted up to seven rounds, and based on this they conjecture that as many as 19 or 20 rounds of RC5P can be distinguished from random using this attack. There is also a corresponding method for recovering the secret key.
Against M6 there are attacks mod 5 and mod 257 that are even more effective.
{{cite conference}}: CS1 maint: multiple names: authors list (link){{cite journal}}: Cite journal requires |journal= (help)Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
In cryptography, mod n cryptanalysis is an attack applicable to block and stream ciphers. It is a form of partitioning cryptanalysis that exploits unevenness in how the cipher operates over equivalence classes (congruence classes) modulo n. The method was first suggested in 1999 by John Kelsey, Bruce Schneier, and David Wagner and applied to RC5P (a variant of RC5) and M6 (a family of block ciphers used in the FireWire standard). These attacks used the properties of binary addition and bit rotation modulo a Fermat prime.
In cryptography, partitioning cryptanalysis is a form of cryptanalysis for block ciphers. Developed by Carlo Harpes in 1995, the attack is a generalization of linear cryptanalysis. Harpes originally replaced the bit sums (affine transformations) of linear cryptanalysis with more general balanced Boolean functions. He demonstrated a toy cipher that exhibits resistance against ordinary linear cryptanalysis but is susceptible to this sort of partitioning cryptanalysis. In its full generality, partitioning cryptanalysis works by dividing the sets of possible plaintexts and ciphertexts into efficiently computable partitions such that the distribution of ciphertexts is significantly non-uniform when the plaintexts are chosen uniformly from a given block of the partition. Partitioning cryptanalysis has been shown to be more effective than linear cryptanalysis against variants of DES and CRYPTON. A specific partitioning attack called mod n cryptanalysis uses the congruence classes modulo some integer for partitions.
In cryptography, M6 is a block cipher proposed by Hitachi in 1997 for use in the IEEE 1394 FireWire standard. The design allows some freedom in choosing a few of the cipher's operations, so M6 is considered a family of ciphers. Due to export controls, M6 has not been fully published; nevertheless, a partial description of the algorithm based on a draft standard is given by Kelsey, et al. in their cryptanalysis of this family of ciphers. The algorithm operates on blocks of 64 bits using a 10-round Feistel network structure. The key size is 40 bits by default, but can be up to 64 bits. The key schedule is very simple, producing two 32-bit subkeys: the high 32 bits of the key, and the sum mod 232 of this and the low 32 bits. Because its round function is based on rotation and addition, M6 was one of the first ciphers attacked by mod n cryptanalysis. Mod 5, about 100 known plaintexts suffice to distinguish the output from a pseudorandom permutation. Mod 257, information about the secret key itself is revealed. One known plaintext reduces the complexity of a brute force attack to about 235 trial encryptions; "a few dozen" known plaintexts lowers this number to about 231. Due to its simple key schedule, M6 is also vulnerable to a slide attack, which requires more known plaintext but less computation.
In cryptography, FEAL (the Fast data Encipherment Algorithm) is a block cipher proposed as an alternative to the Data Encryption Standard (DES), and designed to be much faster in software. The Feistel based algorithm was first published in 1987 by Akihiro Shimizu and Shoji Miyaguchi from NTT. The cipher is susceptible to various forms of cryptanalysis, and has acted as a catalyst in the discovery of differential and linear cryptanalysis. There have been several different revisions of FEAL, though all are Feistel ciphers, and make use of the same basic round function and operate on a 64-bit block. One of the earliest designs is now termed FEAL-4, which has four rounds and a 64-bit key. Problems were found with FEAL-4 from the start: Bert den Boer related a weakness in an unpublished rump session at the same conference where the cipher was first presented. A later paper (den Boer, 1988) describes an attack requiring 100–10000 chosen plaintexts, and Sean Murphy (1990) found an improvement that needs only 20 chosen plaintexts. Murphy and den Boer's methods contain elements similar to those used in differential cryptanalysis. The designers countered by doubling the number of rounds, FEAL-8 (Shimizu and Miyaguchi, 1988). However, eight rounds also proved to be insufficient — in 1989, at the Securicom conference, Eli Biham and Adi Shamir described a differential attack on the cipher, mentioned in (Miyaguchi, 1989). Gilbert and Chassé (1990) subsequently published a statistical attack similar to differential cryptanalysis which requires 10000 pairs of chosen plaintexts. In response, the designers introduced a variable-round cipher, FEAL-N (Miyaguchi, 1990), where "N" was chosen by the user, together with FEAL-NX, which had a larger 128-bit key. Biham and Shamir's differential cryptanalysis (1991) showed that both FEAL-N and FEAL-NX could be broken faster than exhaustive search for N ≤ 31. Later attacks, precursors to linear cryptanalysis, could break versions under the known plaintext assumption, first (Tardy-Corfdir and Gilbert, 1991) and then (Matsui and Yamagishi, 1992), the latter breaking FEAL-4 with 5 known plaintexts, FEAL-6 with 100, and FEAL-8 with 215. In 1994, Ohta and Aoki presented a linear cryptanalytic attack against FEAL-8 that required 212 known plaintexts.
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 →The Greenwood District.
