CSE1006 Study Guide - Hash Function, Collision Resistance, Bitcoin
19 Dec 2022
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H: a hash function which takes an input value and calculates an output value. X: input of the hash function, it could be any data of any length. Y: output of the hash function: a fix-size bit(, it can be 256, 384, 516. A hash function which is used for cryptographic purposes should have these properties: collision resistance. A hash function h is said to be collision resistant if it is infeasible to find two values, x and y, such that x y, yet h(x) = h(y). The collision does exist because the inputs can be any data and the outputs are only 2 to 256 possibilities. But for a good hash function, it"s just impossible to find them in an acceptable time frame even use all the computers to solve this together on the earth. If we can assume that we have a collision-free hash function, then we can use it as message digest.
