All hash algorithms whether they are cryptographic algorithms or non cryptographic algorithms are irreversible. Even in a million years from now they still remain irreversible. In order to understand why they are irreversible I like to use this example:
hash algorithms are intended to be one-way functions, but in theory, it is possible to break them. Many hash algorithms are limited as to how much data can be passed through them. The modulo function makes it impossible to know with certainty what the input it, but a hash algorithm could be broken such that it is trivial to calculate a subset of potential inputs. 
Topic: SHA256 Algo can reverse (Read 213 times)
but the result is the same at the end if you manage to find the initial value from the hashed one.
When you perform a rainbow table attack, you simply compare the hash you want to crack with a list of hashes of known values on a database. So, it's not the same thing.Another thing, rainbow tables is used to crack passwords and even if you find a match, there is a slight chance the initial input is something totally different (collision).
Rainbow table is not the same as reversing the hash function and it is not exactly cracking it either.
It is more like brute forcing the message where you try many different messages (the input) to find a hash that matches the hash you already have.
Yes from a mathematical point of view you're right, but the result is the same at the end if you manage to find the initial value from the hashed one. By the way, @udayantha11 if you are looking for a way to "reverse" one sha256 hash, sometimes Google is the most easy and fast way to get that. There are also some databases available online with millions of hash stored : It is more like brute forcing the message where you try many different messages (the input) to find a hash that matches the hash you already have.
https://md5hashing.net
https://hashtoolkit.com
https://md5calc.com
https://privatekeys.pw
Even rainbow tables, which were helpful to crack older hash functions like LM hash, MD5, and SHA-1 seem to be useless against it now.
Rainbow table is not the same as reversing the hash function and it is not exactly cracking it either.It is more like brute forcing the message where you try many different messages (the input) to find a hash that matches the hash you already have.
Hi All
I have a question that , If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
Not for now, and not even in the coming years fortunately. Even rainbow tables, which were helpful to crack older hash functions like LM hash, MD5, and SHA-1 seem to be useless against it now. As you can see in the link posted by nc50lc and in this one the algorithm is not simple and use several combinations of xor, rotate and shift functions.I have a question that , If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
With the phrase "whoever invented", I think OP is simply thinking that if someone invented something, he must have the knowledge to reverse-engineer it.
...which is not applicable to every invention.
Yeah that's what he has in mind that there can be loophole which the inventor has intentionally put and can exploit the algorithm for making reversible operation on the hash but that's not possible in this case so his confusion is wrong as we have already stated many times to him.But these are some normal things that come in mind when we learn something new and are curious to explore about them. ...which is not applicable to every invention.
SHA256 isn't an encryption algorithm, its hash isn't encrypted.
I think this is where the confusion comes from. OP is confusing hashing (one way functions) with encryption (two way functions)....which is not applicable to every invention.
If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
No. The SHA 256 is one of the most common cryptographic hash functions out there, so you'll also see it in lots of applications and other algorithms in cryptography. It's a fast, one-way function, and it can not be reversed. This means that there is no way to recover the original message from its hash value. It's also very hard to modify the content of the message without completely changing its hash value. And, of course, its uniqueness makes it a perfect hashing algorithm for digital signatures.
SHA256 isn't an encryption algorithm, its hash isn't encrypted.
I think this is where the confusion comes from. OP is confusing hashing (one way functions) with encryption (two way functions).Hashing functions are irreversible. pooya87 already explained in simple terms how it works and I'll give you a practical example:
The output of a hashing function is always a hash with fixed length no matter what the input is. For example, you can take a terabyte file, it's sha256 will be a 256 bits long hash. Do you think it's possible to extract a terabyte data from a 256 bits string!
Hi All
I have a question that , If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
The National Security Agency or what we commonly call NSA designed the SHA-256 first ever back in 2001 but as you said it can't be reversed even by them also because it's designed as one way hash function which is completely irreversible which is why it's used as hashing function not encryption.I have a question that , If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
If it was possible then we could also get private keys from public keys in bitcoin and many more things that use it but it's not possible and which is why it's safe.As others have already provided you with enough resources and example of how we can't determine the value of inputs from the output we get because there are lot of possibilities.
Whoever invented this , he or she can reverse ?
It's not deemed irreversible just because no one knows the algorithm; the algorithm is available to the public.It's irreversible because of the method and the amount of computation required to reverse a SHA256 hash.
If you want to literally see how complex it is, try this demo site: https://sha256algorithm.com/
You'll see the relation to pooya's example where it's extremely hard to guess those "x+y" in every step to reverse because the values have already altered by the previous steps.
The question is more likely decrypting the sha256 hash no one has yet been successful to decrypt it.
SHA256 isn't an encryption algorithm, its hash isn't encrypted. 
The question is more likely decrypting the sha256 hash no one has yet been successful to decrypt it.
Or it is more likely you sent BTC and want to reverse the transaction? but you can't able to reverse the transaction however, you can replace it.
This question if you search a little bit through Google there are many explanations about this no one has yet can able to reverse it.
Or it is more likely you sent BTC and want to reverse the transaction? but you can't able to reverse the transaction however, you can replace it.
This question if you search a little bit through Google there are many explanations about this no one has yet can able to reverse it.
All hash algorithms whether they are cryptographic algorithms or non cryptographic algorithms are irreversible. Even in a million years from now they still remain irreversible. In order to understand why they are irreversible I like to use this example:
I have two numbers (x and y) and I add them. The result is 10. Can you reverse this simple operation and tell me what x and y were? The answer is no because this very simple algorithm (x+y) is irreversible. Now imagine if there were hundreds of such operations happening in sequence where you add values, have overflow, move bits around, mix bits, etc. and you have what a hash algorithm looks like.
I have two numbers (x and y) and I add them. The result is 10. Can you reverse this simple operation and tell me what x and y were? The answer is no because this very simple algorithm (x+y) is irreversible. Now imagine if there were hundreds of such operations happening in sequence where you add values, have overflow, move bits around, mix bits, etc. and you have what a hash algorithm looks like.
I have a question that , If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
SHA256 is one-way. One way means it cannot really be reversed. Maybe this helps somewhat: https://en.wikipedia.org/wiki/One-way_function
Even more: don't you think that if this could have been reversed, people's money would have been already stolen and bitcoin would be already worthless?
SHA 256 is a hash function and we all know that hash functions can not be reversed it's a one way function. So, no.
Simple answer is no.
Hi All
I have a question that , If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
I have a question that , If Sha256 algo created for hashing. and its one way function. Whoever invented this , he or she can reverse ?
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