Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#5001

  1. Hash functions are cryptographic signatures/fingerprints. These are specific standardized outputs given an input.

  2. Hash functions are used in Bitcoin to determine who should receive an award for mining a block.

  3. Collision resistance means that two or more inputs of a cryptographic has function cannot result in the same output.

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#5002
  1. Hash function is a computation that converts data of any form and size into an alphanumerical string also called a HASH
  2. Hash functions are used in bitcoin to hide input data and create a competition of calculated guesses for the hash value range. This is called mining.
  3. Collision resistance is when no 2 unique inputs map to the same output hash.
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#5003

  1. Describe hash functions with your own words
    A: A hash function creates a unique output of a fixed lenght (64 hex charactors) for SHA-256 algorithem.
    for an input string of any length. but it impossible to derive the input from the output - the function is only one-way from input to output. The output is random, no way to have a input pattern that generates an output pattern that one can predict what the input will be.

  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).
    A: the hash function in crypto is used as proof-of-work, validation of the block, and linking blocks together.

  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: Collision resistant means the difficulty finding two or more inputs nounes that will yeld the same output hash signiture.

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#5004

1 Describe hash functions with your own words
A function that takes an input and the output is a “hash” - a digital unique output.
Hash functions can go from input to output but not output to input.

2 Hash functions are used in btc because each transaction is given a unique signature
Each block has a unique hash. If anyone tried to change the information within the block,
ie the transactions, than the hash will change and the blockchain will be broken.

3 What does it mean when we say that hash functions need to be collision resistant?
It means that each hash output is unique to the hash input. If two different inputs
produced the same hash output btc would not work.

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#5005

  1. A hash function is a cryptographic function that returns a HASH - series of numbers and signs. The output is always unique, it’s impossible to have two equal outputs, when the inputs are different. Even changing a small portion of input results in completely unique output.

  2. Hash functions are used to track and give some kind of unique ID to every transaction on the blockchain. In other words, everything on Bitcoin blockchain is a SHA-256

  3. collision resistant means that the cryptographic hash function is not able to produce same output given two different inputs. The outputs should always be unique per input given.

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#5006

  1. Describe hash functions with your own words
    A hash function maps an input of any size to a fixed-size value in a fixed-size number space, essentially converting the input data to a fingerprint in a lossy fashion, meaning that the input data is lost and that the function does not have a reverse.

  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).
    Hash functions are used in signing transactions inside the blocks as part of public-key cryptography, and for the proof-of-work mechanism when mining, where the challenge is to find a version of each block with a hash value in a specific range.

  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 collision means a case of two different sets of data producing the same hash value. Collision resistance in a hash function means that there are no known methods of finding a desired input with a specific hash value in a feasible number of computations.

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#5007

Hash function is a mathematical algorithim than translates data into a alphanumeric string of a certain size.One cannot reverse the hash to find the inputted data. Therefore the Bitcoin hash is only solved in a linear undirectional manner.

The hash is a cryptographic result allowing for security and immutability on the blockchain.

Collision resistant means it hard to find 2 inputs that hash and make the same output. If this happened the blockchain would not be secure and can be tampered with.

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#5008

1 - Hash functions are one-way functions, follow certain mathematical algorithm, with any input, get fixed size output.
2 - In Bitcoin the Hash function is used to hash transaction data. Also mining and finding a nonce requires finding a number that generates a specified hash in combination with data unique to that block.
3 - Collision resistant in this instence means that it is highly unlikely (but not mathematically imposible) to get the same output from a hash function.

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#5009

  1. Hash functions are input and output algorithms used to encrypt data.

  2. The total transactions of a block are given a unique hash input, which create a unique hash output hash for the whole block. Once part of that output hash is solved by a miner, they get rewarded in bitcoin. Every blocks hash it’s also determined by the previous blocks hash, so it’s impossible to go back and double spend on previous blocks.

  3. It means that it’s important for two inputs to never create the same output. If that were to happen, it would be in the algorithm could be broken.

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#5010

  1. Hash functions are functions who can be reversed . They are composed of 1,2,3,4,5,6,7,8,9,a,b,c,d,e,f

  2. You put an information and you use a hash function like SHA256 and then it result with an series of letters and numbers

  3. Wee can’t have two outputs for one input

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#5011

  1. Hash functions are an algorithm that converts information into a specified number of bits that is completely unique to the input which cannot be ascertained from its output.

  2. Hash functions are used to create unique addresses with crypto transactions to show their legitimacy without exposing the information of those involved with a transaction.

  3. Collision resistance is the difficulty to find two distinct inputs that lead to the same output. The more collision resistant a hash function is the more secure it is. MD5 and SHA1 were found to have low collision resistance and are thus no longer used.

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#5012

  1. Describe hash functions with your own words
    Hash functions are specific formulas based on complex math to transpose information/values into an alphanumerical code in “one way”

  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).
    The function is to securely transfer a value from one point (for example John’s wallet) to another point (Jane’s wallet). To complete the transaction successfully its necessary to be confirmed and put into the blockchain (after the block of the transactions is mined - hashed)

  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).
    [/quote]

“Collision resistant” means that two inputs don’t generate the same hash output

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#5013

1- Hash Function is a one way function that process an input to get an output that should be lower than the target value the miner is trying to find.

2- There are many uses of the hash functions in the crypto world including, but not limited to, encrypting function header which contains the transaction data like (version number, time, merkle root, previous block hash) so that no one can decrypt it but the meant recipient.

3- It means it is too hard to find 2 inputs sharing the exact same output in a hash function.

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#5014

Hash function homework

  1. Hash function is a way of uniquely identifying a data input by giving it its own unique output, any change even in the slightest will alter the output dramatically, conversely if the data is changed back to the original input, the output will also return to the original provided the same hash algorithm is used.
  2. Hash functions in cryptocurrencies are used to detect any attempts in changes of data, the hash pointer points to the transactional data/ledger in the previous block. Any attempt to change or hack the data would be immediately noticed by the preceding blocks and nullified due to the changing of the outputs using hash functions.
  3. Collision resistance means each input will have its own unique hash, having 2 different inputs that result in the same hash.
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#5015

Hash function is a mathematical one-way function that creates an unique hash, “a fingerprint”, from a given input.

One-way function means that outcome can be created and verified but it is impossible to generate or find out the input from the output.

Hash functions always produce same unique output from same unique input, kind of like a fingerprint. But even a slightest change will produce completely different hash.

Hash functions are used to link blocks together, making them a chain of blocks.

“Hash functions constitute the backbone of the Proof of Work process. Without confirmation and production of hash transactions, the blockchain would not be tamper-proof and inalterable and it would not be possible to prove who owned which amount of Bitcoin at what time.”

(A take from an article “What is a hash function in a blockchain transaction?” on BitPanda.)

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

“Cryptographic hash functions are usually designed to be collision resistant. However, many hash functions that were once thought to be collision resistant were later broken. MD5 and SHA-1 in particular both have published techniques more efficient than brute force for finding collisions.[3][4] However, some hash functions have a proof that finding collisions is at least as difficult as some hard mathematical problem (such as integer factorization or discrete logarithm). Those functions are called provably secure.[2]”

(https://en.wikipedia.org/wiki/Collision_resistance)

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#5016

  1. Hash functions are a unique finger print created from a function creating an output from an input. It becomes a unique finger print.

  2. They are used to secures the network by encrypting transacton data, as well as creating private keys and public keys and address.

  3. It is statistically insignificant in real world cases that the same input would equal the same hash output.

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#5017

  1. A hash function takes data input and converts that data into a unique output that would be difficult to guess the data input from that output.

  2. Hash functions are used to pass a transaction information anonymously. Bitcoin uses SHA-256 hash function in its algorithm. A private key is generated, a public key is produced from the private key and a bitcoin address is created from the public key. This system provides security by making it extremely difficult for hackers.

  3. Collision resistance is an attribute of a cryptographic hash function. A hash function is collision resistance if it is hard to find two inputs that hash to the same output. Every hash function with more inputs than outputs will have collisions.

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#5018
  1. Hash functions are one way functions where each input produces an output or digital fingerprint.
  2. Hash functions in Bitcoins are using in mining for new transactions on the blockchain.
    1. Collision resistant means two different things not getting the same hash.
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#5019

  1. Describe hash functions with your own words.
    A hash function takes a unique input and created a unique non reversible output. The Hasb function that is most widely used is SHA 256 as this was deemed / has proved to be successfull and provided sufficent security.

  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).
    Hash functions are used by taking the input parameters ( walled address, currency type, amount, timestamp, reciepient address and creaing a unique hash out put that contains the proof of transaction confirmation.

  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 collision is when the algorithm produces the same output with 2 different inputs

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#5020
  1. A hash function is a function that produces a one-directional output that is unique to the input.
  2. Hash functions are used by miners to create new blocks on the blockchain in exchange for newly mined Bitcoin.
  3. Hash functions need to be collision resistant which means that two different inputs should not result in the same output.
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