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SHA-2: A family of two similar hash functions, with different block sizes, known as SHA-256 and SHA-512. They differ in the word size; SHA-256 uses 32-bit words where SHA-512 uses 64-bit words. There are also truncated versions of each standard, known as SHA-224, SHA-384, SHA-512/224 and SHA-512/256. These were also designed by the NSA.
SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. [3] [4] They are built using the Merkle–Damgård construction, from a one-way compression function itself built using the Davies–Meyer structure from a specialized block cipher.
SHA-2 basically consists of two hash algorithms: SHA-256 and SHA-512. SHA-224 is a variant of SHA-256 with different starting values and truncated output. SHA-384 and the lesser-known SHA-512/224 and SHA-512/256 are all variants of SHA-512. SHA-512 is more secure than SHA-256 and is commonly faster than SHA-256 on 64-bit machines such as AMD64.
The goal of the Document Based Question was for students to be "less concerned with the recall of previously learned information" and more engaged in deeper historical inquiry. Hayes, in particular, hoped students would "become junior historians and play the role of historians for that hour" as they engaged in the DBQ. [1]
The wide-pipe hash construction. The intermediate chaining values have been doubled. Due to several structural weaknesses of Merkle–Damgård construction, especially the length extension problem and multicollision attacks, Stefan Lucks proposed the use of the wide-pipe hash [11] instead of Merkle–Damgård construction.
In cryptography and computer security, a length extension attack is a type of attack where an attacker can use Hash(message 1) and the length of message 1 to calculate Hash(message 1 ‖ message 2) for an attacker-controlled message 2, without needing to know the content of message 1.
[5] [6] [7] Although part of the same series of standards, SHA-3 is internally different from the MD5-like structure of SHA-1 and SHA-2. SHA-3 is a subset of the broader cryptographic primitive family Keccak (/ ˈ k ɛ tʃ æ k / or / ˈ k ɛ tʃ ɑː k /), [8] [9] designed by Guido Bertoni, Joan Daemen, Michaël Peeters, and Gilles Van Assche ...
However, students may begin writing during this time; most students take notes on the documents in order to plan out the DBQ. Students are advised to spend 45 minutes writing the DBQ and then 40 writing the LEQ, but there are no rules on when each essay must be worked on. There are three prompts for the LEQ, but only one needs to be chosen.