Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#3256

Its highly unlikely but the possibility exists :slight_smile:

#3257

1: A hash function is a function such that for every unique input you get a unique output and also such that it is always possible to get an output from the input but not the other way around.

2: Hash functions are part of the block hashing algorithm which is used to write new transactions in to the blockchain through the mining process especially in bitcoin. Miners try to combine their own input data in such a way that the resulting hash starts with a certain number of zeroes.

3: A hash function is collision resistant if it is hard to find two different inputs that hash to the same output.

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#3258
  1. A hus function is made of data and converted into 64/128/256 bits. After the process is finished its almost impossible to put back.
  2. Hush function is used with sha256 in securing BTC’s
  3. If we want to make hashes be collision resistant, we must provide two different inputs
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#3259
  1. Describe hash functions with your own words

Hash function takes an input and assign a unique output to that input. The output can’t be reversed engineered to obtain again the input. Every small change (also only one bit) to the input generates a totally different ouput.

  1. How are hash functions used in cryptocurrencies like bitcoin? (Try to research this on your own, we will cover this later in the course but challenge yourself and see if you can find information on this already now).

Hash functions are used as encryption. Miners need to find the correct input matching the hash in order to close and verify a block.

  1. What does it mean when we say that hash functions need to be collision resistant? (We didn’t use the term “collision resistant” in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, that’s how you learn best).

Collision resistant means 2 or more input most likely will not have the same output. every input should have a unique output.

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#3260

  1. A uniq code formed by a message that can consist of both text and numbers, where it is not possible to decode the code afterwards to read the message

  2. It joins the blockchain when a transaction is approved by all decentralized units

  3. It means that it should not be possible for two different messages to end up as the same hash functions

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#3261
  1. A Special type of function in which An input gives a specific output or fingerprint. The input can determine the output but the output can never determine the input.
#3262
  1. A hash function is a special type of function where an input can determine the output but never vice versa.
  2. Hash functions in cryptocurrencies Are used to encrypt messages as to ensure, for example, that a transaction is accurate with respect to amount, and recipient.
  3. Being collision resistant is a way to ensure there is only one matching input to output. Having two separate Inputs that have the same outfit would not be collision resistant.
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#3263

  1. Describe hash functions with your own words.
    Hash functions convert one address space into another without the possibility to convert back to the original.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Generating an SHA-256 hash with a long enough nonce solves a block and rewards the miner.

  3. What does it mean when we say that hash functions need to be collision resistant?
    It means that the same output for two or more inputs is absolutely forbidden.

2 Likes
#3264

An output of a function of any form of data translated into an alphanumeric string of a certain size that is only capable of being solved but not reverse engineered.

A hash provides a lottery system via solving mathematical problems; the lower the targets value is the harder it is to mine a block.

Has a low chance of multiple inputs generating the same output hash

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#3265

Its not really forbidden, but its an issue if it does happen. :slight_smile:

#3266

  1. Hash functions are mathematical function used to encrypt a given set data into a bit of fixed length or size.

  2. Bitcoin hash functions form part of the mining process for block hashing or recording transaction into the blockchain.

3)Collision resistance simply means that two deferent input hash functions should, by no means produce the same hash output.

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#3267

  1. A one way function in which each unique input will produce a unique output.

  2. The hash function, as a one way mechanism, is guaranteed through intricate mathematical equations which do not allow the reversal of a new hash. Bitcoin hash is only solved in a linear, unidirectional manner. Bitcoins blockchain uses these hash algorithms characteristics to run its consensus mechanism. Bitcoin miners essentially work to solve increasingly difficult equations, adding new blocks to the blockchain in exchange for newly created Bitcoin.

  3. A hash function H is collision resistant if it is hard to find two inputs that hash to the same output;
    inputs a and b where a and b don’t equal but H(a)=H(b)
    Users provide hash collisions to prove they used a certain amount of computation to find them.

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#3268

You mean miners? Miners are searching for a new hash that is below a certain target. Even all miners combined are unable to find a collision in a reasonable amount of time. :slight_smile:

#3269

Quick question to the group if I may - could in theory a large institution with a quantum computer crack the hash function SHA256 (go from output to input) in the next few years…?

#3270

  1. Each input gives a unique output of 256 bits. That can never change. A hash is a digital fingerprint. Like a blender and vegetables, can’t be put back together again, that is it can’t go from output to input. The hashing changes the input using Base16 and then to Hex. It’s used to Data integrity check.

  2. A hash function uses an algorithm to take an input of letters/numbers of any length and converts them into an output of a fixed length, 256 bits in Bitcoin’s case. The output is encrypted so its secure to outside parties. The hash confirms the transactions. The hash can not be altered.

  3. 2 different inputs can not get the same hash output.

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#3271
  1. Describe hash functions with your own words
  2. How are hash functions used in cryptocurrencies like bitcoin? (Try to research this on your own, we will cover this later in the course but challenge yourself and see if you can find information on this already now).
  3. What does it mean when we say that hash functions need to be collision resistant? (We didn’t use the term “collision resistant” in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, that’s how you learn best).

1)Hash functions are Conway functions which produce an out put or digital fingerprint

2)Hash suctions are used in mining for new transactions. The inputs of the hash function are made up of the unconfirmed transactions plus additional data relating to time and the previous transaction. To solve the block the miners try and combine inputs with data of their own so that the inputs start with a collection of 0’s. This takes huge amounts of computer power which constitutes POW.

  1. Collision resistance means it is very difficult to find two inputs that produce the same output in a hash function. Most hash functions are not collision resistant. in reality however the chances of two identical outputs being achieved is so small that the ruction has a practical real world use. if two identical outputs were created this would be a collision.
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#3272
  1. A one-way function in which each unique input gives a unique output.
  2. Through lots of random guessing miners adjust signature data until a hash produces n-zeros. Also, blocks contain hashes from previous block in the chain making validation easier.
  3. It needs to have a very low probability of two inputs generating the same output hash.
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#3273
  1. Hash functions encrypt data to a specific base output.
  2. Hash functions are used to encrypt transaction data
  3. Collision resistance means that it is impossible for two different inputs to have the same hashed output.
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#3274

  1. Hash functions are universal translators for computers that receive data in the form of digits, letters or media and translate them into an alphanumeric string. Each unique input has a unique output. The outputs can never be reversed to find the initial data.

  2. In crypto currencies, hash functions are used to encrypt transaction data.

  3. A hash function is collision-resistant if it is hard to find two inputs that hash to the same output

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#3275

Atm quantum computers are only good at particular tasks and its definetly only a matter of time when SHA256 will be broken. When it happens (hopefully before) the network will have to hard fork to a new algo to keep its security.

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