SHA256, 64 characters using only 0-9 or lowercase a-f

Making 1.15792089E+77 total possible combinations. Is it possible to crack the input for its given hash?

  • 1
    Hi San, welcome to the community. I assume you mean practically possible to brute force it. Who's your adversary? How much time does he have? What type of resources does he have available? Is there any context on the input?
    – user284677
    Commented Aug 23, 2023 at 13:34
  • I'm learning still but I'll try to provide what you ask
    – San
    Commented Aug 24, 2023 at 0:51
  • Here's an example of a known string 9ed5b75c13e4d0aad3742b6602801b3bfb4df970efd97806119d7187ddbb7aa4 Here's its hash 9de84032082a2695d60353556b55f5985d0ba0191e62e552aee1deb7d5c7d95a Here's another known string b8f496197a46724fdef265f539fcb1427f4161cde62f3cb3735155ff42ba9b26 Here's a hash WITHOUT the string known other than same length and character types as known strings ed928f305a2ed7ab5795f1eddaa57fdd5d412c1c6e80d6fd082388587eb0cdb7 Can this be bruteforced with early luck?
    – San
    Commented Aug 24, 2023 at 1:02
  • So the input to SHA256 is a hash. It's safe to say that you can't practically brute force that. Do you know where the first hash comes from? Do you have the context of the initial input?
    – user284677
    Commented Aug 24, 2023 at 5:07
  • 1
    Did you look this up at all? I googled your title and got tons of hits. Including the duplicate as the 2nd hit.
    – schroeder
    Commented Aug 24, 2023 at 8:57

1 Answer 1


Assuming the input is totally random, not in your lifetime. The total hash rate of the Bitcoin network at this time is 400 Million Terra Hashses per second. At that rate it would take 9e48 years worst case. Average case somewhere short of that but still well beyond the lifetime of an individual or any economic opportunity of the crack. It is probably safe to assume no adversary has a hash rate that many factors beyond the hash rate of the bitcoin network.

Lastly there may exist multiple valid combinations for a given hash even under the given constraints. It would likely be a short list but without a means to check it, there is no way to determine which is "correct."

Rubber-hose cryptanalysis is more likely in these scenarios.

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