Reading assignment: Hashing

Blockchain and Bitcoin 101
#785

  1. Bitcoin uses the hashing algorithm SHA-256

  2. **Why is hashing algorithm SHA-256 really hard (Almost impossible) to brute-force? **

Cryptography hashing functions are probabilistic, meaning no matter how many times you parse through a particular input through a hash function, you will always get the same result. The only way to find an input from an output has is through brute-force (pretty much impossible). This is like a trial and error method, where you go through many many inputs and see if it matches with the output.

So in SHA-256, there is 2^256 possibilities. To find an input, you need to go through 2^256 output possibilities to find the input. Good luck with that.

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#786
  1. SHA-256
  2. Because of Pre-Imaging Data. It is infeasable to determine the input data based on the output hash (a 256 digit encrypted code). The only way to determine this is brute force (random guess) and the amount of time to brute force attack would need to be more than several lifetimes of guessing every second of every day. This could eventually be done with Quantum Computing but, to my understanding, there are contingencies if this came to be a reality.
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#787

Q1: [SHA-256]

Q2: the process would be too time consuming rendering it useless

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#788
  1. SHA-256
  2. Because of the Pre-Image resistance. It’s almost impossible (infeasible) to determine the input data of H(A) based on the output of the hash function.
    The only way to do it’s by random guess and it will take some many time that’s why absurd give it a try.
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#789
  1. Secure Hashing Algorithm 256
  2. The hashing algorithm produces an output that is improbable to reverse engineer and arrive at the original input
#790
  1. Secure Hashing Algorithm 256. (SHA-256).
  2. because it takes too much computational time and resources. With SHA-256 you need to do 2^256 computations (in the worst case scenario for the hucker) or 2^255 (in the average scenario). Even its possible, it takes so long that make it useless by the nowdays computers. Perhaps with quantum computers no, but we have time to adapt…
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#791

Trail and error makes you go through many inputs to see if it matches with the output. You switched the input and output in your explanation.

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#792

  1. SHA-256

  2. Brute force will pretty much never work, unless you´re the luckiest person alive. To put it in a mathematical perspective, finding x using 1 unknow variable is a easier than using two unknown variables. But in hashes the value of each variable is dependent on the coin it´s made for. For example bitcoin, SHA-256. Which creates a 256-bit string.

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#793
  1. SHA-256
  2. You would have tohave to pick a random input, hash it and then compare the output with the target hash and repeat until you find a match. With a 256 bit hash that of course takes ages.
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#794

  1. SHA-256

  2. It’s easier to break the collision resistance than the preimage resistance. You need sqrt(2^256) = 2^128 attempts to have 50% probability to get the right answer.

#795

1.SHA-256
2. It would take too much time to get it right because there are soooooo many different possibilites. In order to do it though, you would need to use the hash of the block, take the nonce, add them together and hash it again, compare it with the difficulty level, and do it over and over again, untill the result is lower than the difficulty level.

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#796
  1. SHA 256
  2. It is really hard because it would take ages to put two inputs together to get the same output
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#797
  1. The Bitcoin hashing algorithm is called SHA-256.
  2. The SHA-256 algorithm is almost impossible to solve with brute force because its pre-image resistance takes too long to decipher.

A interesting post I came across . . .

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#799

1: SHA-256
2: There are so many possibilities it would take so long that it would not matter.

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#800
  1. What is the hashing algorithm called used in Bitcoin?

The Bitcoin hashing algorithm is called SHA-256

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

SHA-256 is really hard to brute-force because it takes a lot of computational effort and resources. In order to find a collision you need to do approximately 2^128 computations (including the Birthday paradox theory) which is a really large number and takes centuries to compute.

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#801
  1. The bitcoin blockchain uses the SHA-256 hashing algorithm.
  2. The possibility of 2 inputs creating the same output are so minuscule, it would take several lifetimes to occur.
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#802
  1. What is the hashing algorithm called used in Bitcoin?

SHA-256 is the hashing algorithm for PoW consensus protocol.

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

It is a one way function, non-invertible. It is easy to calculate a hash for a given input, but difficult given a resulting hash to determine the original input.

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#803

SHA 256
On average, it would take 2 to 256th power / 2 attempts to brute force break the algorithm

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#804
  • What is the hashing algorithm called used in Bitcoin?
    SHA-256
  • Why is this hashing algorithm really hard (almost impossible) to brute-force?
    It would take donkey-monkey years probably a couple of centuries to get the same out put from two different inputs.
#805
  1. sha 256
  2. It is very hard to find out the output of the function´s input.
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