Reading assignment: Hashing

Blockchain and Bitcoin 101
#1790

  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?

    Because brute force means trying random possibilities until you find the answer. The problem is, it would too long to do that because there are too many possibilities.

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#1791

  1. SHA-256 (Secure Hashing Algorithm 256)

  2. This algorithm is infeasible to brute-force because the probability of solving it is very very low. Some miners may get lucky but you have to be extremely lucky for your results to be below the difficulty level resulting in a new block.

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#1792

Miners are not really brute forcing SHA256. They are just searching the hash below the target threshold. Brute force means you want to find an input that would result in the same hash you’re trying to hack. :slight_smile:

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#1793
  1. SHA-256
  2. The brute force method chooses a random input and compares it to the hashing output. Getting the correct input is almost impossible because it needs to go through 1.7 X 10^38 inputs on average before it find the correct hash. This would take too long to the point that it doesn’t even matter.
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#1794
  1. SHA256
  2. Number of possibilities is so big.
#1795

Ah great that makes sense! Thank you! :blush:

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#1796
  1. SHA-256
  2. because it is not possible to determine the original input from the hash value. 256 bits of entropy makes it infeasible to find correct one by brute-force.
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#1797

  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?
    It takes too long to decipher.

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#1798
  1. SHA-256
  2. its unique and very difficult to find 2 inputs to produce the same output in a hash function.
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#1799
  1. Bitcoin uses the Secure Hashing Algorithm 256 or SHA-256
  2. The amount of inputs and outputs that must be searched for a correct match makes brute force attacks on SHA-256 incredibly difficult.
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#1800

  1. the hashcash proof of work function

  2. because it is too hard to reverse not like encryption

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#1801
  1. SHA256
    total possible combinations: 2^256 ~= 1.16 ×10^77
  2. The computational time required for even the fastest supercomputer built today (June 2020, Fugaku Supercomputer, 415.5 petaFLOPS) will still require 2.79 ×10^59 seconds (8.84 ×10^51 years) to crack the hash by brute force. Even if the fastest supercomputer gets lucky by managing to guess just 0.1% of all combinations, Earth would already have become supernova by then.
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#1802
  1. SHA-256
  2. Because this is what the whole network is trying to do. Bruteforcing it’s way so that the block contains all the transactions hashed and re-hashed with the nonce while resulting in a hash that suits the set difficulty level. You cannot do this alone and be building the longest chain. Instead the collective network of participants do this and no single entity stays in control of the block production.
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#1803

sha 256

in order to decrease collision as well as making brute force attacks harder to be successful

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#1804

I wouldn’t call that brute force. Mining refers to miners searching for a new hash that suits the target requirement, while brute forcing usually means trying to find an input from a hash. :slight_smile:

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#1805

  1. SHA-256 (Secure Hashing Algorithm 256)

  2. Because you would have to guess randomly and there are so many combinations that it would take a long time.

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#1806
  1. SHA-256 is the hashing algorithm used in Bitcoin.
  2. Increases security leading to immutability of the blocks. It is hard because you have to make an infinite amount guesses to figure a certain hash algorithm.
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#1807
  1. SHA-256
  2. You have to pick random input and hash that, then compare to the original to see if it matches. Due to the very large number of potential answers it takes a very long time.
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#1808

1)What is the hashing algorithm called used in Bitcoin?
Its called SHA-256. ETH’s its called Keccak-256.
2)Why is this hashing algorithm really hard (almost impossible) to brute-force?
Its really difficult to trace back the input value of each hashed output because hashing creates an encrypted output by using a fixed length of characteristics. It makes it difficult to trace back its origin.

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#1809
  1. SHA-256
  2. Brute force would mean trying to guess the hashes and there is almost unlimited number of them.
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