Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#3115
  1. A hash function takes a unique input and produces a unique output, there are different hash functions but the main point is that the input can never be determined from the output, it is a one way process.
  2. Hash functions are used in cryptocurrencies to record transaction details without exposing the original data, it is also used to incentivise miners to maintain the network as they get rewarded for trying to calculate the answer to complex mathematical problem involving a hash.
    3.Collision resistance could be described as difficulty of finding more than one input that produces the same output to a hash function. Its should be computationally unfeasible if a hash function is collision resistant.
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#3116

  • Describe hash functions with your own words
    Hash function is a one way function that takes certain data input and gives a output which is unique to the input data. The out put is an encryption of input data with SHA256 algorithm.

  • 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 provide digital fingerprint of input data. This feature can be used to encrypt the transactions data and store the keys in database. Bitcoin is a database of blocks of such data that are cryptographically linked together.

  • 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).
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Hash function should not produce same output for multiple inputs.If for example some one can produce same digital signature for some arbitrary data encryptions then he/she can manipulate the block chain. Hence greater the collision resistance safer will be the block chain.

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#3117

  1. Describe hash functions with your own words
    A hash function is a one way function, meaning that with each input you should get 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).
    bitcoin takes transactions as input and run them through a a hashing function to derive and output hash.

  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 is collision resistant when you don’t get the same output hash when using two different inputs.

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#3118

Thanks for the correction :+1:t4:

#3119
  1. Describe hash functions with your own words

A cryptography function that takes any unique input and converts it into a word of specific length and base for example 256 bit and base 16 number.

  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).

The algorithm is a bit complicated to put it in one sentence but it takes previous block hash for sure, current data some counter and nonce to create a hashing computational problem to solve.

  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 means that the function is very not likely to provide the same hash output for two different inputs. collision resistance is a hashing functiona property

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#3120

Homework on Hash Functions - Questions

  1. Describe hash functions with your own words
    Hash functions take unique inputs and produce unique outputs so that even the slightest change in an input will create a completely different output. The most secure hash functions are unidirectional so you can’t crack the hash and read the decrypted 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).
    Hash functions in cryptocurrencies are used to encrypt the block header so that it’s always equal or less than the Target hash because that’s the only way they can successfully add their mined block to the blockchain and get the Bitcoin reward.

  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’s hard to find two inputs that hash to the same output.

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#3121
  1. Describe hash functions with your own words

A Hash Function processes a unique input in a unidirectional flow to produce a unique output “digital fingerprint” that cannot be used in identifying the input variable.

  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).
    Bitcoin mining uses the hashcash proof of work function; the hashcash algorithm requires the following parameters: a service string, a nonce, and a counter. In bitcoin the service string is encoded in the block header data structure, and includes a version field, the hash of the previous block, the root hash of the merkle tree of all transactions in the block, the current time, and the difficulty.

  2. 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).

The hash function must be difficult/near impossible for 2 competing inputs to produce an identical output.

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#3122

1.) Each unique input you put into a hash function, it will produce a unique output, such as a fingerprint.
2.) They are used to generate fixed-length output data which acts as a shortened reference to the original 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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#3123

Homework on Hash Functions - Questions

Describe hash functions with your own words. A function which takes any random input that is expressed in numbers, letters, alphanumeric, etc and provides a unique output which essentially becomes that inputs unique digital footprint expressed in a different manner in the output of a fixed length. In bitcoins case a 256 bit unique identifier.

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 to assign a unique digital footprint to a transaction providing a secure transaction. Time and data from the previous transactions are also tied into the footprint.

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). Each input will have its own unique output for the most part. It is not impossible just extremely unlikely for a unique hash output equal to another hash output belonging to a different input.

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#3124

A hash function is a cryptographically secure one-way function e.g. f(a1) = b1 and f(a2) = b2 then b1 and b2 is very difficult to be the same.

#3125

How is this used in Bitcoin? :slight_smile:

#3126
  1. Describe hash functions with your own words
  • A hash function converts mathematically an input (numerical value) into another value called output, where that output has a certain, fixed length. A given input will always produce the same unique output. Each extremely similar or different input in a particular hash function will always produce a completely different output. The key characteristic feature of a hash function is that the computational operation must be kind of impossible to be reversed, meaning that the input cannot be identified by applying a mathematical operation (function) on the output. The output of a hash algorithm is basically an unique encrypted map of the input.
  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).

-By doing a beginner research, I’ve learned:

  • In cryptography, the hash function is part of the block hashing algorithm that is used for writing new blockchain transactions through the mining process. In cryptocurrency mining, the function’s input is the most recent and not-yet-confirmed transaction. The input also contains small additional binary data related to the timestamp, plus a reference to the previous block.
  • The property of a unique input giving a unique output as a result of a hash function is critical to the mining proof-of-work algorithm; in order to obtain a valid block, the resulting hash has to start with certain digits of zeroes.
  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 means it is hard to find two different inputs of any length which can result in the same hash. In other words, for a hash function h, it is hard to find any two different inputs x and y where h(x) = h(y). Another used term for this property is collision-free hash function.
    Since a hash function has a fixed hash length (compressing function), it is impossible not to have collisions. The collision-free only confirms that these collisions should be hard to find (creating increased difficulty for an attacker who tries to find two input values with the same hash). If a hash function is collision-resistant then it is also second pre-image resistant, which means that for a given input and its hash, it should be hard to find a different input with the same hash.
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#3127
  1. hash functions are creating a unique output from an input and they are irreversible
    2, hash functions are the back bone of mining because they offer an unique output and this output is permanent
  2. collision resistant means that two inputs can`t never create the same output
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#3128

Describe hash functions with your own words
It is a function that gives every input a different output. Everything is in numbers and the specific hash function being used gives a certain value to the input. Small input changes result in a totally different output.

  • 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 mining is the use of the SHA-256 hash function. This is where they need to get either equal to or less than the target hash in order to add a mined block to the blockchain.

  • 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).

This means that every output is different for every input. Two different Inputs cannot have the same output and this is good because it decreases the chances of getting hacked and is good for security.

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#3129

How are hash functions used in cryptocurrencies like bitcoin?

They’re used to encrypt a information that is private

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 is that two different inputs can’t have the same output. Even though collisions

exist, they are tolerated because of the highly improbable likelihood of occurring.

#3130

Describe hash functions with your own words

It’s a function that can transform arbitrary-sized data into a fixed value.

How are hash functions used in cryptocurrencies like bitcoin?

They’re used to encrypt a information that is private

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 is that two different inputs can’t have the same output. Even though collisions

exist, they are tolerated because of the highly improbable likelihood of occurring

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#3131

  1. Hash function is the algorithm used to run a blockchain network. It consists of an input which produces an output in a one way direction. Ie an output cannot be used to calculate what the input is. If this can be done, then the blockchain algorithm isn’t secure.

  2. Hash functions are used in cryptocurrencies like bitcoin by creating new blocks whenever a successful verification of a hash function occurs. Which in turn verifiers are then given mining rewards.

  3. Hash functions need to be collision resistant meaning that no set of two different inputs should ever produce the same output. If a network isn’t collision resistant, then it is not secure and can be attacked.

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#3132

  1. Hash function is a unique set of output characters used to identify a unique input. The output will have the same amount of fixed characters regardless of the input. If the input changes slightly, that then is recognized as a unique input, and will result in a unique hash function.

  2. In bitcoin the hash function is used to write new transaction on the blockchain through the mining process.

  3. Collision resistance, no two data set should generate the same hash output, and to be collision resistance is to generate unique hash output from unique inputs. If separate data set generate the same hash output, it means that data can be compromised.

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#3133
  1. Hash function is the coversion made from an input
  2. Helps broadcast transactions through the chain
    3.no two data set should generate the same hash output
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#3134

  1. For each unique input, it will produce a unique output. (Basically if you give this function a number, you will get a fingerprint for this number. If you give another number, you will get a completely different output). You cannot go from output to input.

  2. Multiple things such as deriving keys to block signatures. The inputs of the hash functions are none confirmed transactions, which miners try to calculate the hash to add new blocks in the chain.

  3. Basically making it very difficult or almost impossible for two inputs to result in the same output.

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