Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#5101

1.make a unique finger print
2.they are used in writing new transactions on the blockchain.
3.each input should have its own unique hash.

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#5102

a hash function is a data string of any length that is uniquely scrambled and converted into a one way irreversable fixed length string or digital fingerprint.

hash functions are used in bitcoin to scramble the transaction data (which creates transaction ID), block headers (for mining blocks on the blockchain), and public keys (which provides an address where the transaction points to).

collision resistant in bitcoin terms is more based on security to make sure that each hash is unique and does not create multiples.

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#5103
  1. Hash functions are one way. Each unique input has a unique output. The function works from input-output never other wat around

2.Hash functions are used in bitcoin especially mining. This one-way mechanism is guaranteed through mathematical equations which do not allow the reversal of a new hash.

  1. Two different inputs will never have the same hash output or its highly unlikely to achieve.
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#5104
  1. Hash Functions- cryptographic inputs that solve an equation leading to an output
  2. Hash Functions are the building blocks of Bitcoin. It is from the computation of these that Bitcoin is ā€œbackedā€ by mathematics
  3. Collision Resistant means that two different inputs will have a high probability of not having the same output- while possible, it would be difficult to find
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#5105

  1. Hash Functions are unique functions that only work towards finding an output. They canā€™t be reversed to decipher inputs. They also create a unique digital fingerprint for each and every input and they continue to create unique fingerprints for every subtle change to each and every input.

  2. Hash Functions in cryptocurrency very securely encrypt the data of transactions providing benefits like Provenance, Security and Immutability, and Finality.

  3. ā€œCollision Resistantā€ speaks to the unlikely chance of two different inputs achieving the same output hash.

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#5106

  1. Hash function is a method in which by inputing data you obtain an unique code (finger print) as an output.

  2. Transaction information (input) are ran through a hash algorithm to get a code (output) by which the transaction can pass anonymously.
    Hash functions are also used to generate private keys.

  3. Collision resistant hash function refers to the the fact that for two different inputs the outputs should not be the same.

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#5107

  1. Hash functions is a computation to go from an input to output, but you canā€™t go from an output to input.

  2. Probably in mining, to reward people (computers) who create a new block in the blockchain.

  3. Each input has it own output, and two differents outputs canā€™t have the same outputs and vice versa. It means that it is unique and very safe.

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#5108
  1. A hash function is a cryptographic calculation that results in a specific output (digital fingerprint) from a specific input. This calculation can only go one-way and canā€™t be reversed.
  2. Creating addresses, public- and private keys. To create transactions the data also goes through the hashing algorithm.
  3. Different inputs shouldnā€™t result in the same hash (output).
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#5109
  1. Describe hash functions with your own words
    A: Hash functions are computational equations that take an input and create a completely unique output that can only be duplicated by entering the exact same input again. It is not possible to deduce the input from the output; the function only goes one direction: input to output.
  2. How are hash functions used in cryptocurrencies like bitcoin?
    A: Iā€™m guessing that the hash function creates a unique output from the input of wallet addresses the transaction the BTC is moving to and from, as well as the amount. And maybe a timestamp? This gives a unique record of the transaction without disclosing any data about the sender, recipient, or amount of BTC transacted.
  3. What does it mean when we say that hash functions need to be collision resistant?
    A: No two inputs to the hash function can create an identical output. Every input has a completely unique output - 1:1
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#5110

  1. Describe hash functions with your own words
    Hash functions is this application which used to create a unique output from input

  2. How are hash functions used in cryptocurrencies like bitcoin?
    It used to write the transactions into the blockchain

3.What does it mean when we say that hash functions need to be collision resistant?
It means that no two inputs hashes must match to the same output hash

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#5111

Number 2 is written perfectly :hushed: you really are something

#5112
  1. Describe hash functions with your own words:

A function that converts any string of data (can contain letters, numbers, comma etc.) into a nonreversible 256 bits data (like a fingerprint).

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

Hashing data converts it into a unique kind of Fingerprint, which is nearly impossible to trace back to the original input. Each block in the blockhain has its own Hash and contains the previous blockĀ“s hash.

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

Finding 2 different inputs for the same output is known as a collision. A hash algorithm is collision resistant, if it is hard (nearly impossible) to find two inputs that hash to the same output.

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#5113

  1. A hash function is a function where an unique input gives you an unique output. Itā€™s impossible to do it the other way around.

  2. We use hash functions to store and secure data, transactions, files or whatsoever on the blockchain.

  3. It means that two different inputs canā€™t have the same output.

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#5114

1- Describe hash functions with your own words

Hash functions convert an input to an output, where the same input always will lead to the same output. The output normally is a Hex Value (where the length depends on the hash function type md5, nltm, sha256ā€¦)
Hash functions are one-way functions. You cannot go back from output to input. If that happens the hash function becomes worthless.

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).

They are used to incentivise miners. Miners are solving mathematical problems with time liit and produce hash codes. Like in a lottery only one haashcode will win to produce the next bitcoin block which is rewarded with bitcoins.

3- What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).

collision resistant means that is is nearly impossible (computer power / time / needed iterations) to find 2 inputs that lead to the same hashcode.

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#5115

  1. Describe hash functions with your own words
    A hash function is a mathematical function that converts a numerical input value into another compressed numerical value. The input to the hash function can be of any length but the output is always of fixed length. It is a one-way function, meaning that is impossible to reverse the hash function. By looking at the output we cannot know what the input was.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    In cryptocurrencies like bitcoin hash functions are used to avoid counterfeiting of transactions and prevent malicious actions. One of the most common uses of the hash function is in the process of generating the Bitcoin address. Secondly, hashing is a key process in the proof of work mechanism in Bitcoin: it is used for block creation.

  3. What does it mean when we say that hash functions need to be collision resistant?
    Collision resistance means it should be hard to find two different inputs of any length that result in the same hash. This property is also referred to as collision free hash function.

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#5116
  1. Vital in keeping the blockchain upon which Bitcoin exists safe and secure. They are the building blocks upon which the technology was developed, and without them, the entire cryptocurrency ecosystem would cease to exist.
  2. Universal translator for computers. It is able to receive any form and size of data, including digits, letters, or even larger media files, and translates them into an alphanumeric string of a certain size.
  3. Collision resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b such that H(a) = H(b).
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#5117

  1. Hash functions are unique digital fingerprints that only go one way; each unique input produces unique output.

  2. Hash functions are used to pass transaction information anonymously. For example, Bitcoin uses the SHA-256 cryptographic hash function in its algorithm.

  3. Collision resistance: is a property of cryptographic hash functions: a hash function is collision resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b such that H ( a ) = H ( b ). Ultimately we need a unique output for every unique input.

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#5118

  1. A hash function is an algorithm or an equation that transforms any given input into a specific and unique output. Even the slightest difference in input will produce a totally different output from this hash. Furthermore, Bitcoin hash functions cannot be ā€œreverse-engineeredā€ in the sense that you can derive an input from a given output. In other words, the function is a one way street.

  2. Hash functions are used in Bitcoin mining, where miners try to create new blocks by solving increasingly difficult strings of hashes or equations. Using SHA-256, miners try to arrive at a target number that is equal to or less than a blockā€™s ā€œheaderā€ (idk what this is btw), which can be a number anywhere between 1-256. If a miner does not arrive at a ā€œwinningā€ number, it must begin calculating again from scratch.

  3. Collision resistance refers to the likelihood of any two inputs resulting in the same output for a given hash function. For bitcoin, it is important for this likelihood to be as close to zero percent as possible. Otherwise, itā€™s like having two correct answers to one questionā€¦
    I do have a question thoughā€¦
    Is this possible? like - can there be a new block formed twice from two different locations?

#5119

Each block within the blockchain is identified by a hash, generated using the SHA256 cryptographic hash algorithm on the header of the block (block header contains previous hash, Merkel root, timestamp , difficulty target and nounce), what I am trying to say if new block to formed twice at different location the inputs should be the same and that is not possible.

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#5120

  1. A hash function is a one way function where the input is a unique fingerprint that produces an unique output or as we call it, digital fingerprint.

  2. The work required to secure a block cannot be copied, erased, or reversed. Hashing also keeps Bitcoin secure by encrypting transactions data through SHA-256.

  3. Collision resistant mean that it is very hard to find 2 different inputs that produce the same output.

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