Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#5161

your home assignments are annoying lol

#5162

a hash function is a mathematical way to get an create unique outputs that cannot be reconstructed to find the inputs.
hash function combines the message-passing capabilities of hash functions with security properties.

collision resistant is saying that the hash input cannot be found with the output. if you can figure out the inputs by the output then its not collision resistant.

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#5163

  1. Describe hash functions with your own words
    Hashfunction is a one-way function that creates unique specific output for each unique specific input.

  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).

  • it’s used to digitally-sign the transaction anonymously
  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 no two inputs can produce same output. If it’s not collision resistant then we can replace a transaction with other transaction that produces same output.
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#5164

  1. Describe hash functions with your own words
    Specific kind of formula with the property that it can only be executed in one direction. It can be used for encryption or as an indicator that changes in data have taken place.

  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).
    Used for the mining process and writing new transactions into the Bitcoin blockchain. The algorithm needs to give a certain outcome for the miner to show proof of work. As the outcome is (partly) known, but the exact input to get there is unknown because of the one directional formula, the minor needs to give it many tries to come to the wanted outcome.

  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).
    It means that there can be no occurrence in which different inputs lead to the same output.

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#5165

Homework on Hash functions - Answers:

  1. Hash functions is a function with output as a hash.
  2. Bitcoin uses hash functions for generating block headers of blockchain and public keys.
  3. The term “collision resistant” means impossibility to find out the input from hash output.
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#5166

  1. A hash function is a unique identifier for any given piece of content. It’s also a process that takes plaintext data of any size and converts it into a unique ciphertext of a specific length.

  2. Secure Hash Algorithm 256 is used by the Bitcoin network to produce block consensus, securing the network.

  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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#5167

  1. hash functions are basically secure mathematical process which convert data such as digits and letters into a secure unique string, they can only be converted from input to output, not the other way round so are very secure, Bitcoin uses the hash fuction SHA256.

  2. hash functions are used to write new transactions into a blockchain through the mining process

  3. it means that it is hard to find two inputs which will hash the same output

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#5168
  1. Inputting any combination of words, letters, or numbers and generating a Hash code that will always be the same total numbers 12, 24 or whatever protocol is used

2.They are used in bitcoin as the core method of mining blocks, each new block hash contains the block hash signature from the previous block to help secure the network. They are also used in crypto by wallets to protect the users private keys

3.Avoiding generating the same Hash signature for 2 different transactions

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#5169

  1. Describe hash functions with your own words
    #A hash function creates a random hash that is not reversible. It creates a unique fingerprint.

  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).
    #Bitcoin’s hash is unique but somehow linked to the previous block. In this way a chain is created so that you can always see what happened in the past.

  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).
    #A hash function is collision resistant if it is difficult to find two inputs that hash to the same output

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#5170
  1. Hash functions are equations that result in unique outputs of a fixed length to unique inputs of any length. These has functions can be of different basis and varying output size, the one used in Bitcoin is called SHA-256 and is on base 16 (if I recall correctly). Aside from that characteristic, they function only in one direction and not be reversed. From X we can obtain Y but we cannot obtain X from Y.
  2. In prior lecture, Ivan explained that every hash input creates a different and unique output. For mining purposes, there is the need to try different inputs to arrive to a determined target, and over time, as the degree of complexity increased, the inputs required needed to be at same time smaller but larger in length (to solve the output). For example, on Block 453194 mined on 15th February 2017, the miner had to input a number with 18 zeros in front to reach the required target (
    000000000000000000e907ebdb890c7f46c0649829b60e98ff5cb5e2b83fcc77) As seen here: https://www.blockchain.com/btc/block/000000000000000000e907ebdb890c7f46c0649829b60e98ff5cb5e2b83fcc77
  3. Collision resistance is a desirable quality in cryptography where in a particular hash function the likelihood of finding two different inputs that result in the same output is considered unlikely.
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#5171

Describe hash functions with your own words
Hash Functions are one way functions that transform input text with variable lenght to unique output with fixed length.

How are hash functions used in cryptocurrencies like bitcoin?
A hash function in Bitcoin is used to hash transactions in each block.
It uses the hash of the previous block to create a new block.

What does it mean when we say that hash functions need to be collision resistant?
A hash function is collision resistant if it is hard to find two inputs that hash to the same output.

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#5172

Hash function in a cryptographic algorithm that contains from certain input,and a output that is unique,and completely connected and dependant on the input.

hush functions in bitcoin are important for running the consensus mechanism…these algorithm is crucial in mining,and by solving it you basically get a bitcoin.

collision resistant basically means that for certain input you get certain output connected only to that input. if you change even a slightly detail in the previous input,you will get completely different output. every input has its own output

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#5173
  1. A function where each unique input produces one unique output and cannot be reverse-engineered to determine the input from the output of the hash function due to its complexity.
  2. They are used to secure the information that is provided in the input, to mask the transaction. They are used to prevent fraudulent transactions, double-spends in blockchain, and secure passwords.
  3. The term “collision-resistant” means there are no two inputs that produce the same output.
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#5174

  1. Describe hash functions with your own words.
    Hash functions are functions that will produce a unique output for every unique input. Another characteristic of a hash function would be, we cannot reverse engineer it, and it is always linear. We can only input, and get an output back – instead of the other way around. (we cannot try to get the initial input, by working it backwards from an output)

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions are used to mine Bitcoin, by solving an intricate equation that uses SHA-256 to process an input (the currently-unverified transaction), and then produce an output when the equation is solved in the form of a block that is added into the chain (blockchain). Then, the miner who managed to solve the equation will get a fraction/a number of Bitcoin as a reward for validating the transaction (like a service fee).

  3. What does it mean when we say that hash functions need to be collision resistant? Collision resistant means that it is extremely hard to find two inputs that result in the same output. However, it does not necessarily mean that it is impossible, it is just very unlikely to happen due to the large pool of possibility for an output.

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#5175

  1. a hash function is a one-way function, which gives an alphanumerical output for a given input, but it is not possible to find the original input from just the output. Even a slight change in the input makes a very different output.

  2. Hash functions are used in Bitcoin to process new transactions on the blockchain. The inputs are a combination of the current transaction to be confirmed, plus data from the previous transaction in the chain plus additional data related to time.

  3. Collision resistance means that it is extremely rare (though theoretically not impossible) to have 2 inputs producing the same output through a hash function.

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#5176

  1. Hash functions are those that receive any input and produce a unique alphanumerical hash (fingerprint) of that data (of certain size). They are built in a such way that cannot be reversed, this means if you know the fingerprint you are not able to figure out or reproduce the original input.

  2. Hash functions are used in the mining process. In this process, a block of unconfirmed transactions is fed to a hash function and a hash digest is generated. The miner uses this hash digest and adds some input from his/her end to generate an output that contains a certain amount of leading zeroes.

  3. Collision resistance is a property of hash functions and this means that is it is very hard to find two inputs that hash to the same output. Since the hashes (output) are limited range, obviously there are more inputs than outputs, so it is possible that two different inputs could produce the same hash. Being collision resistance means that even when it is possible, it is extremely difficult.

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#5177
  1. Hash Function is a one way function, for each unique input into a hash function, the hf will produce a unique digital fingerprint, however if this input is changed the unique digital fingerprint will also change. HF vary in terms of input to outputs and outputs to inputs, the MD5 has been figured out however the SHA256 has not, if it was to be figured out BTC would be in difficulty.
  2. Through the mining process, hash functions are a part of the ‘block hashing algo’ used to write new transactions -
  3. It is important to not have two or more of the same inputs leading to the same output
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#5178
  1. A hash function is a one-way function that implements a mathematical algorithm that maps input data of any length to fixed-length data as output.
  2. Blockchains rely on hash functions for generating cryptographic keys and hashing the transaction blocks.
  3. A hash function is collision resistant if it is hard to find two inputs that hash to the same output value.
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#5179
  1. A hash function is an algorithm performed on some kind of data that produces a string that can only be produced by the original data, and yet can’t be reverse engineered to find out what the original data was
  2. Mining is done by brute force guessing numbers until they have find one with a has function that meets certain criteria, at which point the block’s transactions are added to the ledger and the reward is distributed
  3. It is the rarity of two possible data sets having the same hash, therefore the infeasibility of brute force guessing
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#5180

  1. Hash functions are mathematical functions which only give an unique output given an unique input. It is not possible to obtain the input of a hash function given an output.

  2. The input of a hash function gives an unique output of a fixed length which is used to find a suitable block to be added as next for the next block of the blockchain in question. If the block is accepted by the network’s consensus mechanism we call it block mining. Each hash of any suitable block is linked to that of the last block in the given blockchain and impacted on its actual digits and their orders.

  3. This is the probability of two inputs hashing the same output being extremely low. If functions are not collision resistant the safety and trust of the network containing them would be severely compromised.

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