Reading assignment: Hashing

[SecondOpinion]

1. SHA256
2. Due to the number of possible inputs being a high min-entropy distribution it takes so long to brute force the input from the output that it can be considered the same as impossible.

[Bellantoni]

Ok I need courage to ask the dumbest questions ever on BTC.
So mining enables to confirm transactions.

1. What did miners do before there were enough transactions to keep them busy?
2. When is a bitcoin created? Is it when enough block of transactions have been validated and confirmed or is it a completely different procedure?
   Thanks for any help.

[Boas]

1. SHA256

2. The encryption is Pre Image resistant meaning that it requires computational power outside of current available technologies to reproduce an input to the chain. However this is not impossible and could lead to future issues with quantum computing.

[SecondOpinion]

Knowing little more than you i believe the two processes are different. The miners will find solutions to the hashing algorithm regardless of transactions transmitted to the network. Including transactions into a block garners the miner additional rewards as there is a fee specified by each person sending a transaction to be paid to the miner who first finds and has their solution validated by the network. The block reward is paid to the miner with the first accepted solution regardless of there being transactions included or not. The protocol used to demand the first come first served with transactions but this was changed to replace by fee meaning (some time a few years ago) that the tx with the highest fee was placed into the block first by default unless a miner specifically adjusts their setting to do otherwise. Some still are happy to include zero fee txs in their found blocks but if you do this your tx might take weeks or months to get placed into a block.

[Agnie]

1. SHA- 256
2. It is difficult to brute force because of the amount of data; it would take to long to reverse outputs to get to the original input.

[Mauro]

@hyrekin

we all put 100% trust in the bitcoin development team

No. Miners update if they want to. If the developers wanted to increase the maximum supply of bitcoin, no one would update.

We don’t use sha256 only in bitcoin. It is very safe for now. Super computres are a bit of a tricky topic. If we have hundreds of big miners mining in the world, I still think its gonna be hard for a single super computer to take over the network.

[Mauro]

Correct. Nonce just changes the hash.

[Mauro]

@CryptoScangg

2. If the data input gets changed in any way, a completely different hash is created

Correct. But why can’t we just simply take the output and brute force our way back to the input?

[Mauro]

@coin999

2. In order to find a hash collision you need roughly sqrt(2^256) = 2^128 items for 50% probability of some pair having the same hash. 2^128 = 10^38.5 is a very large number. If it takes 1 nanosecond to compute a hash, then it would take 10^22 years to compute 2^128 hashes. Also the memory to store these would also need too large a volume.

Collision is different from the brute force attack. In brute force we are trying to find out what was the input based on the output. A collision is finding two inputs that lead to the same output. Either way both are very hard.

[Mauro]

As @SecondOpinion already said. To kick start the bitcoin network we needed a big block reward, which was 50 at the start. Now its 6.25. Bitcoins are created when a miner finds a new block regardless if it has any transactions or not. Thank you for helping out @SecondOpinion.

[Mauro]

@Boas

2. The encryption is Pre Image resistant meaning that it requires computational power outside of current available technologies to reproduce an input to the chain. However this is not impossible and could lead to future issues with quantum computing.

Hash functions don’t encrypt. They hash. A brute force is not about reproducing an input to the chain. Its about finding the input based on a given hash.

[cryptoforyou]

#1. SHA-256

#2.its really hard to find a mach in a hash. imagin you’r in prison, but the gaurds say if you solve the password, you can escape. you agree. then, when you look at the code, you see that it is a 256 diget code, there are 62 different carrecters, (for every letter lowercase and capital, and numbers), and so your stuck in prison for the rest of your life.

[carmen1408]

1. SHA-256 (Secure Hashing Algorithm 256)

2. Because the odds on break through a hash are too small, you are either the luckiest man in the world or you will spend yearson guessing. There are too many combinations and it just not making any sense.

[Moon5683]

1. SHA 256
2. The number of possibilities are so large brute-force is infeasible

[Clueless_in_USA]

1. What is the hashing algorithm called used in Bitcoin?
   SHA-256 is the one used in the article.

2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
   This process requires the algorithm to search and test all potential “candidates” for a real problem solution and checking whether each candidate satisfies the problems statement. If a solution exists, it will find it. If critical applications have any errors in their allgorithms, there could be serious consequnces. The cost can grow rapidly as problems increase. Thereofre, it is best to use when the size of the problems are limited.

[MrF]

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?

Bitcoin contains so many hash with more added every second, the idea of scanning and testing all existing hash looking for a match is so unlikely and getting harder every moment that we don’t even consider it as a threat.

[Mauro]

@cryptoforyou

#2.its really hard to find a mach in a hash. imagin you’r in prison, but the gaurds say if you solve the password, you can escape. you agree. then, when you look at the code, you see that it is a 256 diget code, there are 62 different carrecters, (for every letter lowercase and capital, and numbers), and so your stuck in prison for the rest of your life.

A bit dark, but correct.

[Mauro]

@MrF

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

Bitcoin contains so many hash with more added every second, the idea of scanning and testing all existing hash looking for a match is so unlikely and getting harder every moment that we don’t even consider it as a threat.

Exactly, Even breaking one hash would be infeasible.

[KryptoS]

Q1. What is the hashing algorithm called used in Bitcoin?
SHA-256 (Secure Hashing Algorithm 256).

Q2. Why is this hashing algorithm really hard (almost impossible) to brute-force?
The number of attempts to determine the input is astronomical and not feasible.

Worst case scenario = 2^256 -1 attempts

Average scenario = 2^256/2 = 2^255 attempts

[SoloDragonGG]

What is the hashing algorithm used in Bitcoin?: the SHA-256 (Secure Hashing Algorithm 256). hashing is generating a 256 bit fixed value or values from a usually much larger string of text using a mathematical function.
So basically, instead of remembering the input data which could be huge, you can just remember the hash and keep track.

WHY IS IT INFEASIBLE (but not impossible) TO BRUTE FORCE -The only protection against brute force is the fact that it takes an inordinately long time to perform a brute force.

Brute force works by simply looking at an output string and going through every possible input string and trying it to guess the correct value, one at a time.
There’s no way to protect against simply trying every possible combination. It would take a really really really long time, and use up a lot of resources that could be directed to better uses.