Is it possible to recreate data if you only know its hash?

Is it possible to recreate data if you only know its hash?

So, no, you can not recreate the original data from it’s hash. The only thing a hash is good for is to compare it with other hashes to see if the hashed data is identical or not.

Can a hash value be used to verify that one copy of a file is the same as the original file?

A hash is a unique serial number for a unique computer file. The serial number contains nothing about the file. The only way to know anything about the file is to recreate it independently through trial and error, where the hash offers nothing but confirmation that the created file matches the original.

Can you hash a document?

Open the Word (not . txt) document and add the hash to the end of the document. Send the hash-appended document. The recipient can cut the hash from the document, save it as UTF-8-encoded text, then calculate the hash.

Does copying a file change the hash?

Even copying the content from one file to another in the same software program can result in different HASH values, or even different file sizes. As a result, these files are considered “near-dupes” for analysis purposes, even though the content is essentially identical.

How do you find the original value of a hash?

One method that can be used is to hash a bunch of values (e.g. brute-force from aaaaaaaa-zzzzzzz) and see which value has the same hash. If you have found this, you have found “the value” (the time is not cheap). “Rainbow tables” work on this idea (but use space instead of time), but are defeated with a nonce salt.

Is it possible to modify a message without changing its hash value?

So basically, no.

Is it possible to modify a file without changing its hash?

So basically, no. As some other posts have mentioned, if you are adventurous and life and death are at stake, you could disassemble the application binary and actually remove the machine language check for the hash. This is varsity-ninja work though. Thanks for contributing an answer to Stack Overflow!

Is there a way to reverse a hash?

You could not reproduce the file in any reasonable amount of time. The reason is that the only way to ‘reverse’ a hash is via brute-force, and considering how large the original file was, it would take you that exact amount of bytes to brute force.

Is it possible to duplicate a crypto hash of a file?

You can have the app quit checking, but no, there is no way to duplicate a crypto hash of an existing file. That’s the point. Does a file exist having your desired settings and with the same hash? possibly

Is it true that hashes are many to one?

To those who say, “hashes are many to one, so you cannot tell what was hashed”: That is true, but of all the many values that hash to that one value, some will be more plausible than others. If you invert the hash above you will have not the least doubt that you found the right input.