Reading assignment: Hashing

Blockchain and Bitcoin 101
#2191

Through my understanding of the read article

1.- SHA-256
2.- Due to the property of hash functions: pre-image resistance and Collision Resistance

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#2192
  1. SHA-256
  2. It would take a very long time to establish a second input that results in the same exact hash
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#2193

You mean the hash of the previous block? :slight_smile:

Ah yes, I meant to say Hash from the previous block.

Not necessarily, difficulty might also decrease if the hash power of the network drops.

Oh okay, Thanks for the correction! :smile:

#2194
  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 with a slightly larger set of inputs, the difficulty increases exponentially which means making random guesses takes too long
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#2195
  1. SHA-256
  2. It is complete randomness and the more people guessing the harder it gets.
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#2196

SHA256 has a fixed size, meaning brute forcing it has a fixed difficulty approximately half (2^256 / 2) :slight_smile:

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#2197

1-> SHA-256
2-> to many possibilities do to the 256 bit cryptography, you have to be extremely lucky if the brute force works and guess the right hash with the right outcome

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#2198
  1. The hashing algorithm used in Bitcoin is SHA 256.
  2. Its infeasible to brute force this algorithm because there are so many possibilities, it would take too long to be worth the effort. You would also have to change every block on the chain to even make a tiny adjustment to one transaction.
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#2199

  1. What is the hashing algorithm called used in Bitcoin?
    Hashing

  2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
    Because the odds are non existant, and you cant affect older blocks in the chain.

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#2200

  1. secure hashing algorithm 256 OR SHA-256

  2. Because of the nature of solving the algorithm, it is essentially a guessing game.

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#2201
  1. SHA-256
  2. The SHA-256 has “pre-image resistance” - meaning that it is infeasible to determine the input data, based on the output hash - the number of variables is far too large to try to figure it out through brute force
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#2202

1.In Bitcoin transactions are taken as input and run through a hashing algorithm which gives an output of a fixed length. Bitcoin uses SHA-256 hashing algorithm
2.there are (2^256 possibilities) and it almost impossible to brute force it. Can take lifetime or be most lucky person on world :slight_smile:

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#2203

[quote=“ivan, post:1, topic:8422”]

  • What is the hashing algorithm called used in Bitcoin?
    SHA-256

  • Why is this hashing algorithm really hard (almost impossible) to brute-force?

You would need to hash random input and compare the output to match the target hash. The odds of finding the match in one’s life time is almost zero.

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#2204
  1. SHA 256
  2. The variations obtained when applying SHA 256 are so vast that it is infeasible to find the corresponding imput to that specific output.
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#2205

  1. The hashing algorithm used in Bitcoin is SHA-256.

  2. Using brute force to find an input would take more time than most people have.

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#2206

1-Sha 256

2- In order to find the input using the output is so difficult.

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#2207
  1. Sha-256
  2. finding the input that lead to known output by trying (brute force) would take too much time. Therfore it in infeasible.
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#2208

Thanks Fabrice, your input is appreciated!

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#2209

  1. SHA-256

  2. There are an extremely large amount of possible answers to the SHA-256 functions. In order to solve the function, one needs to trial the answer in the function. This trial and error method grows increasingly more time-consuming with the increase in possible solutions.

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#2210
  1. SHA-256
  2. Because any small change in the input will cause an output that doesn’t match data in the preceding blocks and will thus get rejected by the network. It would require too much time to change all the preceding blocks.
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