Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#3979

  1. A hash function is a function that gives a unique digital fingerprint to any type of input data in the form of a number. If any part of that input data is changed, the hash function will produce a completely different fingerprint. Hash functions are one way functions which means that you cannot find the original input data using the output.

  2. Bitcoin uses hash functions to add new transactions into the blockchain by mining. Miners use new transactions that haven’t been confirmed yet as input for the hash function and arrange them a certain way to try to get a hash that begins with a certain number of zeros.

  3. Collision resistance means that it’s hard to produce the same hash with more than one unique input.

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#3980

Hash functions are functions that take any sized input and maps it to a specific sized outout. This is done using a one way equations that is practically impossible to reverse except by trial and error/ brute force.

Hash funtions are used inn crypto currencies to like bitcoin to validate the ledger. Every time a block is to be written in bitcoin a sha 256 hash must be performed with a specific output with its target. this also includes all previous data in the header of the information of the input.

Collision resistence is the liklyhood of 2 inputs creating the same output. For a hashing fucntion to be considered good it needs to have high collision resistence. If two inputs can make the same output the hash fucntion can be broken down and reversed.

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#3981

1 The hash function is a one-way input and a non-returnable unique output as a fingerprint.
2 Transactions take place on the bitcoin network, which are verified by the Hash function. Miners receive rewards for verification.
3 It is impossible for two inputs to reach the same output.

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#3982
  1. Describe hash functions with your own words

Hash Functions convert an input to a unique alpha numerical output of a set length determined by the encryption method ie SHA256 is always 64 characters long

  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 heavily used in the Proof-of-Work blockchain consensus algorithm that is used by the bitcoin algorithm as hash functions, are an efficient way to secure data integrity and reduce file size. Hash functions are used to convert input data of any length into a compressed unique fixed length string of characters (also known as a bit string). This output data serves as a unique reference code or digital fingerprint to verify the authenticity of some underlying dataset without the need to actually check the entire dataset.
The hash function is a mathematical algorithm that maps data of arbitrary size to a bit string of a fixed size (also known as a hash). It is designed to be a one-way function, meaning a function which cannot be inverted and recalculated backward to get to the input data.

  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).

It is collision-resistant. A collision happens in a hash function when two different inputs generate the same output. Since inputs can have any length but outputs are fixed-length, obviously, there will be collisions. In other words, there is a finite number of possible outputs for an infinite number of inputs. Collision resistance means that finding two different inputs for the same output should not be possible using smart algorithms or strategy but only by trying every possibility. This is what we call brute-force.

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#3983

  1. Hash functions is a formula created by unique and distinct characters that make up an output from every input which gives it a one way function.

  2. Hash functions are used in cryptocurrencies because it is one of the ways it enables security during the process of messages/processes intended for particular recipients only. A formula generates a hash functions which then helps protect the security of the transmission against tampering.

  3. Collision Resistance requires that two different input messages should not hash to the same output. Due to their very nature hash functions will always have some collisions, meaning two different messages hash to the same output. However, this should be computationally impractical to find.

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#3984

  1. Hash functions are one way functions where each unique input will produce a unique output. If the input is changed in the slightest than the output will be completely different. The input gives you the output but you can never go from the output to the input.

  2. Hash functions are used in cryptocurrencies like bitcoin to reach consensus and to preserve integrity of the blockchain. Miners use hash functions to approve transactions and create the next block. Hash Functions are used to easily double check previous blocks to make sure that nothing has changed.

  3. Collision resistance means that it is hard to find 2 inputs that hash the same outputs.

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#3985

  1. Describe hash functions with your own words
    A hash function is a mathematical process that takes input data of any size , performs an operation on it, and returns output data of a fixed size.

  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).
    In the bitcoin, hash functions are part of the block hashing algorithm which is used to write new transactions into the blockchain through the mining process.

  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).

If two separate inputs produce the same hash output, it is called a collision. If a hash function is collision resistant it’s difficult to find produce the same hash value/output from different inputs

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#3986
  1. An hash function take a piece of data as a input and create a sort of digital fingerprint of that data.
  2. The hash functions are used to confirm transaction and add block to the blockchain. A miner take all the transactions as input and adding his own arbitrary piece of input data (nonce), he used the SHA-256 in such a way that the resulting hash starts with a certain number of zeroes.
  3. It menas that using that hash functions, is infeasible to find the same output for x and y, that is Hash(x)=Hash(y)
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#3987

  1. Describe hash functions with your own words
    A function with 1 unique input that creates a unique output.

  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 hash function can take a unique input and convert it using an algorithm to a unique output, if anything in the input is changed , it will change the output. This can be used to verify that the data from original input has not been changed, if it has, then the output will not be the same. This can be used to verify data on a ledger, a password or any other information inputted before hashed has not changed.

  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 is difficult to find 2 inputs that hash to be the same output. If collisions are easy to find they allow hackers to take an authentic signed message , and substitute it with a different message that produces the same collision but keeps the same signature value of the original.

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#3988
  1. Hash functions is a one way function that cannot be reversed. It is generated by number of unique inputs into one unique string of output.
  2. In bitcoin protocol hash functions are part of the block hashing algorithm, which is a used to write new transactions into blockchain through the mining process. In bitcoin mining process the inputs are the most recent, not confirmed yet transactions. Any change to the input in hash function will result in a different output. This property is crucial to the proof of work algorithm involved in mining. Source: Coindesk.com
  3. A hash-function is a collision- resistant it is hard to find two inputs that hash the same output. Any function with more inputs that output will have those collisions. The harder they are to find the more secure the hash function is.
    Source: Crypto Wiki
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#3989
  1. Hash functions take any input variable of any size and outputs a unique and fixed length output.
  2. Hash functions are used in bitcoin by miners trying to solve blocks to be added to the blockchain. They use the hash function to generate verifiably random numbers until the block is solved.
  3. Collision resistance is the highly unlikely probability that any input will have the same output. However, it is not mathematically impossible.
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#3990

Hash functions have unique input, which produces a unique output.

Each bitcoin transaction uses encrypted hashes to identify the transaction, and place the transaction on the blockchain ledger.

Collision Resistant means that no two inputs will create the same output.

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#3991
  1. For a unique input a hash function creates a unique output
  2. Uses SHA-256, PoW function and Miners adding new blocks to the blockchain following successful verification of the hashes within them.
  3. Two distinct values can’t have same output
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#3992
  1. Hash functions take any input and create a unique output with a fixed length.
  2. In BTC, hash functions are used during the mining process to enable security. The input would be your transaction request which is already encrypted. Miners use that as input, hash it, and the output serves as a unique identifier on the blockchain. This is more commonly known as a digital fingerprint and miners can use this to verify the authenticity of the dataset its verifying without the need to decrypt the original input. The quickest miner to update the transaction and verify the ledger (per transaction) gets rewarded.
  3. Collision resistance is the term used to describe an outcome that is mathematically NOT impossible but the likelihood of the outcome occurring is arguably impossible. For a collision to occur, two different inputs would have to hash the same output. Since the output is a fixed quantity of characters, there is a mathematically defined limit of different iterations. However, that number is so large that you have a better chance of winning the lottery multiple times a day every day for more years than your traditional calculator can fit on its screen. (figure of speech)
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#3993

1 - Describe hash functions with your own words

Hash Functions are complex mathematical functions that allow to assign to an input, of variable size, a single output, such as a digital print, of fixed size. Each change in the input would result in a completely different output. It is a one-way function, that is, it is not feasible to start from the output to reach the 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).

The cryptographic hash function is a special function class that has several properties ideal for encryption and certain properties need to be in order to be considered secure, such as: Deterministic; Quick Computation; Pre-Image Resistence (“brute-force method” / 2 ^ 128 = 3.402823 x 10 ^ 38 times / 2 ^ 127 = 1.701411 X 10 ^ 38 times); Small Changes In The Input Changes the Hash and Collision Resistant.

Bitcoin uses the SHA-256 hashing algorithm (Secure Hashing Algorithm 256); and

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).

Given two different inputs A and B where H (A) and H (B) are their respective hashes, it is infeasible for H (A) to be equal to H (B).What Is Hashing? [Step-by-Step Guide-Under Hood Of Blockchain]

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#3994

  1. Describe hash functions with your own words
    Hash functions is an one way mathematic algorithm that map an input to a totally unique output.

  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 function use as a cryptography which take the input and generate a hashed value of the output in a way that can’t be reversed. This make cryptocurrencies data integrity, and secure against unauthorized modifications. Bitcoin use hash function to encrypt the transaction so that each transaction is unique and not able to modify and remove.

  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 occurs when two input result to an identical output, hence, a good and trustworthy hashing algorithm just as SHA256 is one that is resistant to these collisions. However, every hash function with more inputs than outputs will necessarily have collisions. Collision resistance does not mean that no collisions exist, just that it is simply that they are hard to find.

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#3995
  1. Irreversible (one-way) data transformation device.
  2. Ensure that a transaction from a wallet can be validated using only the private key in the hash function.
  3. The property that a function is so sensitive/chaotic to its input, that it is impossible to have the same output from different inputs (kinda like 1-1 mapping in mathematics)
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#3996

Q1. Describe hash functions with your own world?
A. Hash functions is a process of encrypting an input data with an output that is unique to the unique input.

Q2. How are hash functions used in cryptocurrency like bitcoin?
A. Bitcoin is on a public irreversible ledger called blockchain. When a transaction is initiated(input) a hash function called SHA-256 takes the unique input data and gives us a encrypted unique output that can not be duplicated without the exact unique input. Giving a trustless public ledger using a mathematical algorithm called SHA-256.

Q3. What does it mean when we say that hash functions need to be collision resistant?
A. To be collision free like SHA-256. Two different input can not give the same output.

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#3997
  1. Describe hash functions with your own words

Hash functions are mathematical functions that take input and generate a unique output.

  1. How are hash functions used in cryptocurrencies like bitcoin?

Hash functions are used to encrypt transactions. They are used in the verification of transactions and the addition of blocks to the chain through mining.

  1. What does it mean when we say that hash functions need to be collision resistant?

They need to produce a unique output for each input, ie. two inputs do not produce the same output.

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#3998

1- A hash function is an irreversible function that gives a unique output “digital fingerprint” for a different input.
2- In the bitcoin protocol, hash functions are used in the block hashing algorithm which is used to write new transactions into the blockchain through the mining process. The same goes for other cryptocurrencies.
3- When we say hash functions have to be collision resistant, that means that it should be that no two, or more, inputs result in the same output. That way the output is unique for any input.

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