Reading assignment: Hashing

[Fabrice]

@CliffC

Why is this hashing algorithm really hard (almost impossible) to brute-force?
It is infeasible to find the input value by only knowing the output. It would take such a long time to calculate this to the point where it wouldn’t make sense to attempt.

It’s impossible to calculate, because if you change 1 character, the whole hash is scrambled again. The only way is to keep guessing and hashing until you find the particular hash

[Fabrice]

@sweeesh

the hashes plus the nonce then hashed again makes it almost impossible to guess.

You are talking about mining by guessing a nonce so the hash value is low enough.
Here we just mean to brute force a hash, wich is keep guessing the input, hash it and compare if the hash is the same.

[Luche]

Hashing Homework

1. The hashing algorithm used in hashing bitcoin is called SHA-256, or Secure Hashing Algorithm 256.
2. This hashing algorithm is very difficult to brute-force because it would take a very long time to pick a random input, hash it and then compare the output with the target hash, and repeat as many times as necessary to guess correctly.

[Taiwanprincess]

1. SHA-256
2. due to pre-image resistance, one has to go through all random possibilites (unless you are the “lottery-winner” with only few attempts) - al lot of calculations needed to get to the input one is looking for

[TheeM916]

1. Secure Hashing Algorithm 256 a.k.a. SHA-256

2. It is nearly impossible to break down because of the length of the hash. If a hacker attacks even 1 block of the chain, the result would domino effect and change the block data. Since the chain is connected through linked lists and pointers, it would, in turn,change the block before it, and the block before that, and so on and so on, and so on. which is basically impossible.

[wfells]

1.) Sha-256

2.) Because you have to pick random hash the probablity of being right would take not only forever but next to impossible

[angela]

1. SHA-256
2. Due to Pre-Image Resistant and Collision Resistant properties, it would take so long to find a match, that it would no longer matter.

[Roberto_Moreno]

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?
   The hashing algorithm its really hard to Brute-Force because of Pre-Image Resistance. It will take so long to that is doesn’t matter.

[Ingridharp]

What is the hashing algorithm called used in Bitcoin?
The hashfunction in Bitcoin is SHA 256

Why is this hashing algorithm really hard (almost impossible) to brute-force?
It is infeasable to brute force because you would spend more then a lifetime in computations to break the 2^256 change to find the input of the hash

[WesselVosloo]

a) SHA256
b) Because of Pre-image resistance you can not determine input from output due to the security of the 256 bit encryption

[John_Montagne]

1. What is the hashing algorithm called used in Bitcoin?
   Sha256 algoririthm
2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
   Because the hashfunction is a one way function. The input cant be read by the fingerprint from the output. To crack the input bruteforce is needed and takes too long to guess because there are too much possibilites to guess from. this would take a lifetime.

[santalittlehelper1]

1 what is hashing algorithm called shaw 256
2 2 brute force is writing each hashtag after another till you hit the one you want because of the possible numbers it could take hundreds of years to access this way 1-10/24

[0xMac]

1. Sha256
2. Average scenario is that you will guess the answer is one in a [colossaly huge number] and under time.

[AB-MANDO222]

1. What is the hashing algorithm called used in Bitcoin?
   The hashing algorithm used inside of bitcoin is named sha -256.
2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
   because it is both nearly impossible and ineffective to have found two inputs that are producing the same output in the original hash function

[CryptoSho]

1. SHA256

2. The odds of identifying 2 hash inputs that would be the same is just about impossible.

[JTzong]

1)SHA-256 is the hashing algorithm used in Bitcoin.
*2)This algorithm is near impossible to brute force because it is very difficult to find 2 inputs to produce the same output in a hash function.

[Lrrr]

1. The Bitcoin hashing algorithm is SHA256 that stands for “Secure hashing algorithm 256bits fixed output”

2. It is almost impossible to brute-force SHA256 because it would take an enormous amount of time and resources that is just infeasible to find a collision. Also in a blockchain contex each block’s hash is linked to the previous one making an immutable history of transactions.

[Shashi]

1. What is the hashing algorithm called used in Bitcoin?
   SHA256

2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
   It is almost impossible to find the 2 inputs that match the output.

[Mauro]

@Storm.chain

2. Because the blocks are linked in a chain, so to alter the details of one would require modifying the details of all preceding blocks simultaneously, which is a near impossible feat.

This is 100% correct, but the question was more focused towards the hash function in general. I will rephrase the question. Why is it really hard to guess the input of a given hash?

[Mauro]

@Farid

(and probably very few actors even possess this kind of computing power today

There is no way near that much computing power today. 2^256 is a verryyy large number of possibilities. It would take millions of years with the current technology. It is more likely that whoever wants to break SHA256 will try to look into any sort of vulnerabilities in the hash function itelf.