Reading assignment: Hashing

1.) SHA-256

2.) It is almost impossible to brute force because the odds of finding the right hash in a hash function are unfathomable for just one person’s lifetime, even a bunch of people’s lifetime’s spent solely searching for the right hash would most likely not work.

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  1. The Bitcoin hashing algorithm is called Sha256.

  2. It is infeasible to effectively brute-force the Bitcoin hashing algorithm because of the vast number of possibilities.

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Sha 256 is the hashing algorithm used in Bitcoin.
The possibility to find the input based on the output is so difficult its impossible

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Not quite, though the 51% attack does involve calculating SHA256 it is not about finding the hash of an input but having more hashing power to mine blocks faster than the rest of the network :slight_smile:

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  1. What is the hashing algorithm called used in Bitcoin?
    SHA 256 (Secure Hash Algorithm 256)

  2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
    It’s because the probability of finding the right input is more than 1^100 and you will have 10 minutes to figure out the input. But there will only be a fraction of a chance that you guess the right hash, so that’s why we say it’s feasible and not impossible to brute force it.

When it’s sha 256, does automatically mean 256 bit in all cases?

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  1. SHA-256

  2. Because it will take 2^256-1 to find the input value meaning that you will have to spend every second of every day trying to guess ‘hashings’ without sleeping for the rest of your life and you wouldn’t even come close, neither your children if they tried to do the same nor their children or their children and even then if you finally break the hash by that time it wouldn’t even matter.

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Yes, 256 basically means how many bits there are int the output of a hash function :slight_smile:

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  1. The hashing algorithm that is currently used by bitcoin is called SHA-256, which produces 256-bit hashes.
  2. With brute-force alone, this hashing algorithm can be really hard to implement and sustain because it takes so much time to actually do that it is basically impossible without utilizing the merkle tree and the trail between nodes that allows minors to create new blocks more efficiently.
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  1. sha256
  2. Too many possibilities and would take too long to break.
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What is the hashing algorithm called used in Bitcoin?
SHA-256

Why is this hashing algorithm really hard (almost impossible) to brute-force?
My understanding of it is linked to the number of different hashing values that the hash function can produce. During this couple of lectures, I in the beginning had a hard time seeing why you just couldn’t reverse engineer the hash value to the input if you will know for example the SHA 256 algorithm. With a search on google I found easy explanation of it, for example introducing some concepts around “clock arithmetic” and simpler ones like if you pick two random numbers between 1 and 9999 that you add together which results in your hash value. The last one will even be hard to reverse engineer to the input if you for example add the numbers 2+300=302, it will be hard for anyone to reverse engineer on the first try that the hash “302” will be your input 300 and 2, it can be a lot of other numbers as well.

My understanding why Bitcoins hashing algorithm “SHA-256” is almost impossible in the present moment is for the fact that it is consider to be impossible today to reverse engineer and the 256 bits hash output value is consisting of a HUGE number of different values so a brute-force in todays day and age is consider infeasible and practically impossible.

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1.the hashing algorithm used in bitcoin is Sha-256
2.Sha-256 the hashing algorithm is hard to do so forcefully because finding the inputs that have the same output is near impossible and also is timing consuming.

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  1. What is the hashing algorithm called used in Bitcoin?
    SHA-256
  2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
    There are so many possibilities, it will take too long
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  1. What is the hashing algorithm called used in Bitcoin?
    -Secure Hashing Algorithm 256 (SHA 256)

  2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
    -For a smaller data set it is easy to guess the hash value corresponding to the input data because you can match all the individual input data to the hash function, but when it comes to bitcoin, transactions are carried out so many times it would be hard to match the hash of a single block in the blockchain to its original input by making the same pure random guesses.

  1. SHA-256
  2. Because the probability for brute-forcing every input (hashing the input, and compare the output with the output of the input in question) and find the exact match is extremely low (you need to try it around 2^255 times (half of 2^256) in general).
  1. SHA-256: based on a 256-bit hash function.

  2. Brute forcing is a way to automate guessing. Guessing the right answer between 2 possible answers has a 50/50 chance, and will take 2 tries to get the right answer, but guessing the right answer when there are billions+ possible answers, is very hard. With bitcoin even harder because the data (and the number of possible answers) keeps growing.

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  1. Secure hashing algorithm 256
  2. it takes so long it doesn’t matter and to find a random input that matches the output is possible but highly unlikely.
  • SHA-256
  • Because nobody have the amount of computational power (and time) needed to check by brute force the insane number of possibilities.
  1. SHA 256
  2. Its an equation very easy to calculate in one direction, so for example from private key to public key, but nearly impossible in the other direction with the computation power at hand to man at the moment .
  1. SHA 256: Produces a 256-bit hash.
  2. The brute-force method basically means that you have to pick up a random input, hash it and then compare the output with the target hash and repeat until you find a match. While it is possible to break pre-image resistance via the brute force method, it takes so long so it is not important anymore.
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  1. SHA-256
  2. because in order to find a match, it would take near-impossible amount of resources and time
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