i get that SHA256 isn’t considered “encryption”, it’s something to do with hashing. so, if i encrypt “hello” into a random string of characters, why is it said to be impossible to decrypt it back to “hello”? if you had a maths equation like P = (k * 10 / G) / (4x * 5gl), it’s possible to work backwards to find the value of k or g eventually. why not with SHA256? is it something to do with random numbers?
In: Mathematics
Hashing algorithms throw away information, meaning the initial data can’t be reconstructed uniquely.
Imagine that I tell you “My (rather poor) hashing algorithm works by multiplying together two numbers: and the result is 162”.
There are a lot of numbers that can be multiplied together to form 162. It can be 6×27, or 2×81, or 18×9, and so on. Any one of these could be the correct answer, but you can’t tell for sure because I threw away important information.
Hashing algorithms do the same thing. They take what you give them, and while they are generating their final result they will use methods (like multiplication or xor) that easy to do one way, but can be impossible to go the other direction without knowing what the original data was.
Once you’ve gotten the final answer you don’t really have any good way to find the original data except by guessing, and there are a *lot* of possible options to guess before you get a matching answer.
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