Question

I came across a tool WINMD5FREE which generates an unique hash code to each file. It accepts any file type and gives an output of 33bit hash code. Is there anyway to reverse that process to obtain the file back from that hash code?

Also a fair doubt. While downloading some popular tools there are other links of Md5, SHA, etc besides download links what do these represent?

Answer 1

You seem to have misunderstood what a hash code is. They are made to be irreversible.

You can use them for all sorts of things. Say you wanted to know if you have the same file on two computers but the file is too big to send over the network, simply calculate the hash code for the file on each computer, if you get the same numbers the files are the same, if one single bit differs you will get different hash codes.

Hash codes are also used for password authentication. When you sign up for a website you enter your password. This string is hashed and stored in a database. Since the hashed password is not reversible no one (with some caveats that we won’t get into here) can find out your password. When you want to log in you enter your password again, the system hashes the string and compares it to what it has stored in its database. If the hashed strings match the system can be confident (again, with some caveats) that you typed the right password.

Read more on http://en.wikipedia.org/wiki/Hash_code