Пошутите что-нибудь сами

Пошутите что-нибудь сами Serious Cryptography SHA-1 The SHA-1 standard arose from a failure in the NSA's original SHA-0 hash function. In 1993, NIST standardized the NSA's SHA-0 hash algorithm, but in 1995 the NSA released SHA-1 to fix an unidentified security issue in SHA-0. The reason for the tweak became clear when in 1998 two researchers discovered how to find collisions for SHA-0 in about 2^60 operations instead of the 2^80 expected for 160-bit hash functions such as SHA-0 and SHA-1. Later attacks reduced the complexity to around 2^33 operations, leading to actual collisions in less than an hour for SHA-0. SHA-1 Internals SHA-1 combines a Merkle–Damgård hash function with a Davies–Meyer compression function based on a specially crafted block cipher, sometimes called SHACAL. That is, SHA-1 works by iterating the following operation over 512-bit message blocks (M): H = E(M, H) + H Here, the use of a plus sign (+) rather than ⊕ (XOR) is intentional. E(M, H) and H are viewed as arrays of 32-bit integers, and each two words at a same position are added together: the first 32-bit word of E(M, H) with the first 32-bit word of H, and so on. The initial value of H is constant for any message, then H is modified as per the above equation, and the final value of H after processing all blocks is returned as the hash of the message. Once the block cipher is run using the message block as a key and the current 160-bit chaining value as a plaintext block, the 160-

На скриншоте поста в соцсети сверху написано «Пошутите что-нибудь сами», а ниже показана страница учебника по криптографии с выделенными терминами «compression function» и «SHACAL». Шутка в том, что вместо готовой шутки автор предлагает читателю самому разобраться в сложном техническом тексте и найти в нём юмор; это реакция на просьбу пошутить или на ситуацию, когда объяснение выглядит намеренно непонятным. EN: A social media post says “Make up a joke yourselves,” followed by a textbook page about cryptography with the terms “compression function” and “SHACAL” highlighted. The joke is that instead of providing a ready-made joke, the author asks the reader to work through a dense technical passage and find the humor themselves; it is used as a reaction to a request for a joke or to an intentionally incomprehensible explanation.

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