Reading assignment: Hashing

Blockchain and Bitcoin 101
#764
  1. What is the hashing algorithm called used in Bitcoin?

SHA-256

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

Because on average it is so time-consuming to brute-force (which means to hash all your input data and compare these hashes to the hash you want to know the input of) that it doesn’t make sense to even try.

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#765

What is the hashing algorithm called used in Bitcoin?

The hashing algorithm in Bitcoin is called SHA-256.

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

The length of the output creates an almost impossible amount of different combinations (2^256), 2^128 computations with the Birthday paradox theory. It will take too long time to break because you have to try them randomly.

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#766

Bitcoin uses SHA-256

This hashing algorithm is almost impossible to brute force because of pre-image resistance. Given H(A) it is infeasible to determine A. Cryptgraphic hash functions are deterministic so you can try to brute force all the possible results, but this will lead to an incredibly huge number of operations, on average 2^256/2=2^128

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#767
  1. SHA-256
  2. Because brute forcing will most likely require a very large number of “guesses” (2^256/2) that it is highly infeasible but not impossible.
#768

1.SHA- 256
2.it takes so long that it doesn’t matter.

#769

  1. SHA (secure hashing algorithm) 256

  2. 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. The worst case scenario is that you find the match at the end of all the data, average case scenario is that it will take very long, so much so that it will no longer matter.

#770

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

  2. The hashing algorithm is really hard to brute force because doing so will probably involve a huge number of guesses due to the vast number of possible original inputs.

#771

What is the hashing algorithm called used in Bitcoin?

  • SHA-256

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

  • Because the process is brute-force based and moreover it’s random: means that you need a huge mass of computation to match the hash and find it’s input
#772
  1. What is the hashing algorithm called used in Bitcoin?
  • SHA256
  1. Why is this hashing algorithm really hard (almost impossible) to brute-force?
  • Brute-forcing SHA256, would require guessing the input combinations of up to 2^256 bit combinations before reaching a successful output hash combo. To my understanding this would take, with current computing power, amounts of time that I simply can’t fathom. Supposedly quantum computing may some day easily break SHA256, but as of today, and as of my knowledge this isn’t feasible.
#773
  1. SHA 256
  2. if you would like to find the input or string that generated the output or hash you would need, on average, 2^256/2 iterations, which is an incredibly big number
#774

What is the hashing algorithm called used in Bitcoin?
SHA-256.
Why is this hashing algorithm really hard (almost impossible) to brute-force?
The number of possibilities is so high with a 256 hash that it would make it very hard.

#775

SHA256 produces 256 zeros and ones. It is 256 bits long. It has 2^256 possible hashes.

@Sainsbury The possibility of finding the input based on the output is impossible. You would have to guess what the input was, but it would take you an eternity to try all the possible combinations.

#777

What is the hashing algorithm called used in Bitcoin?
Sha 256

Why is this hashing algorithm really hard (almost impossible) to brute-force?
Because it would take many years to try and guess all the possible combinations of a hash. One small change will drastically change the hash you get.

#778

Yes. And the input does not have to be text only either. It can be a picture, a video or any other file. And even a single pixel being wrong in apicture would result in a completely different hash.

@MirkoB 2^256 does not equal to 2^128. 2^256 divided by 2 is 2^255. To make you understand it lets think of 2^4. This is achived by multiplying 2x2x2x2. So dividing 2^4 just removes one x2, leaving us with 2x2x2 which is 2^3.

#779
  1. SHA-256
  2. Brute-forcing or randomly guessing a hash algorithm is possible, but would most likely take way too long because the number of possibilities is astronomical.
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#780
  1. BTC hashing algorithm is SHA-256
  2. The number of possibilities is so large that working backwards from the output to determine the input is not feasible.
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#781

  1. A formula generates a value(s) from a string of text using a mathematical equation that will result in a hash.

  2. The properties of the hash function can’t be changed - they are immutable.

#782

Of course. Bitcoin does not ever change its way of hashing the blocks. But the key point you need to understand is that the there is so many possible hashes it is impossible for it to be brute-forced.

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#783
  1. The hashing algorithm used in Bitcoin is SHA256
  2. Brute-force is infeasible in SHA256 because the sheer amount of input variables would take too long to “guess” and find the corresponding hash.
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#784

Glenn_CostaRica

1. What is the hashing algorithm called used in Bitcoin?
Bitcoin’s hashing algorithm is called SHA-256.

2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
The kind of function that the SHA-256 is makes it impossible to reverse-engineer the output of the function in order to obtain – to “guess” or hack – the original input. Therefore, the only method that anyone could use to try to hack the way back to the original input, would be throwing random numbers one by one until the correct one appears. This would be the brute force method. Nevertheless, since the SHA-256 generates 256bit-long hashes, the number of possible candidates in astronomically immense. You would have to guess the correct answer among 2^255 options. This number is so big that the temporal length of the entire history of the Universe would still be short in order to generate enough guesses as to be lucky and hit by chance.

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