get data from generated hashcode()

i have a string(name str) and i generate has开发者_如何学Gohcode(name H) from that , i want recieve orginal string(name str) from recieved hashcode(name H)

The short answer is you can't.

Creating a hashcode is one way operation - there is no reverse operation. The reason for this is that there are (for all practical purposes) infinitely many strings, but only finitely many hash codes (the number of possible hashcodes is bounded by the range of an int). Each hashcode could have been generated from any one of the infinitely many strings that give that hash code and there's no way to know which.

You can try to do it through a Brute Force Attack or with the help of Rainbow tables

Anyway, (even if you succeeded in finding something) with those methods, you would only find a string having the same hascode of the original, but you're ABSOLUTELY not sure that would be the original string, because hascodes are not unique.

Mmh, maybe absolutely is even a bit restrictive, because probability says you 99.999999999999... % won't find the same string :D

Hashing is generating a short fixed size value from a usually larger input. It is in general not reversible.

Mathematically impossible. There are only 2^32 different ints, but almost infinitely many strings, so from the pigeon hole principle follows that you can't restore the string.

You can find a string that matches the HashCode pretty easily, but it probably won't be the string that was originally hashed.

GetHashCode() is designed for use in hashtables and as thus is just a performance trick. It allows quick sorting of the input value into buckets, and nothing more. Its value is implementation defined. So another .net version, or even another instance of the same application might return a different value. return 0; is a valid(but not recommended) implementation of GetHashCode, and would not yield any information about the original string.

many of us would like to be able to do that :=)