Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#5181
  1. Describe hash functions with your own words
  • Hash function is like a computer language that has been created out from an input creating an output that can never be reversed.
  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 make it so that its impossible to crack the code. The benefit it provides bitcoin is security and immutability.
  1. 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 it makes it impossible for example two different inputs to come up with the same output. Or for the output to have the different inputs. Each one should be unique.
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#5182

Hash functions allow you to encrypt data by creating a unique fingerprint for a given input. For a hash function to be secure it should be reversible.

Hash functions in cryptocurrency are used as part of the block hashing algorithm for storing new transactions in the blockchain. The hashed data includes newly created transaction together with their timestamp and previous block.

a hash function is collision-resistant if it is hard to find two inputs that hash to the same output ;

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#5183

  1. Hash functions are used to protect data integrity. Using a specific algorithm, you take the total input of an object and calculate a single mathematical result. For example, if you wished to compare one copy of a dictionary to another, you would sum up all the digital values of the contents (including spaces and special characters) and output the result. Then perform the same function on the other dictionary. If they are identical then the results would be the same.

  2. Hash functions are used in Bitcoin to ensure the legitimate continuity of the chain. Nonces, plus PoW makes it almost impossible to corrupt a chain such as Bitcoin.

  3. Hash functions must be collision resistant in Bitcoin because if two different inputs could have the same output, it would make maintaining the integrity of the chain more difficult.

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#5184

  1. Hash functions convert input to a unique output.

  2. Hash function is used in bitcoin to pass tranfer information anonimously

  3. It means that a hash function is mathematically impossible to solve, atleast with the available technology

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#5185
  1. Hash functions compress different size and type of data into fixed length string of letters and numbers, many times as hexadecimal representation of bits (but some other numeral base / radix can be used too). This would be then a fingerprint, signature of that input data, which proofs its authenticity.
  2. They are used in more than one way: generating wallets and accounts in those wallets - generating private and public keys, mining in PoW by sealing already validated transactions into blocks, for adding those blocks into an immutable blockchain, etc.
  3. One input should always only have one unique output, in a collision 2 different inputs create a one, same output (hash). So, hash functions need to be collision resistant in order to such event does not occur!
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#5186
  • Describe hash functions with your own words

Hash function is an mathematical equation that takes in some kind of input and it transforms it in set of hexadecimal numbers of certain length.

  • 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 blockchain hash number represents the number of block, previous transaction data, transaction data to be made (qty of money from address x to address y), current balance and other number for hash number to be even more difficult to be generated.

  • What does it mean when we say that hash functions need to be collision resistant?
    It means that it has to be practically impossible to find hash number with different block data, that is the same to the hash number of the block in which we have changed something.
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#5187
  1. Hash functions are unique inputs which always gives an unique output. This gives the power and security of the network because nobody can reverse an input in the network.
  2. They are used to permanent record the transactions in the blockchain.
  3. Hash functions need to be collision resistant because this provides the security and the trust that users have in the network.
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#5188
  1. Hash functions are functions that turn a unique input into a unique output. You canā€™t determine the input based on the output.
  2. Mining becomes more like a lottery when using these hash functions, you cannot calculate the winning input based on the output. Instead what you can do is use more computer power (buy more tickets) to increase your chance of winning. This gives miners the incentive to mine with more machines, but everyone still has the same relative chance of finding the winning input.
  3. Collision Resistant means that thatā€™s itā€™s hard to find 2 ore more different inputs to produce the same output. So a function should be Collision Resistant to minimize the chance of this happening
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#5189

describe hash functions with your own words?
is a universal translator for computers, it is able to receive any form or size of data , incl digits, letters or longer media files and translate them in a alphanumeric string of a certain size, standard size of a hash function in use: 64 bit- 128 bit - 256 bit, with cryptocurrency and btc is used the SHA256
How are hash functions used in cryptocurrencies like bitcoin?
every transaction (input) is put in a hash ( output ) and these hashes are saved in the blocks and every new block of the transaction of this hash will have the data of the transaction from the block before. So it makes that it cannot be changed through the SHA 256
hash functions has to be collision resistant?
That each input will have always his unique hash algorithm, that is almost impossible to generate the same output hash if the input is not the same

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#5190
  1. Computational algorithm to retrieve a ā€œfingerprintā€ or an output of the given inputs.
  2. Hash functions are used in Bitcoin mining. Previous hash in an attribute in the current block along with the current block hash.
  3. Collision resistance refers to the ability to find two separate inputs that when hashed, each produce the same output. If they produce the same output, they are not very collision resistant.
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#5191
  1. Describe hash functions with your own words
    hash functions is a one way function, in which you cannot go from output to 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 takes all transaction data from a block and make a hash from the data as an input.
  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).
    that it is rally hard to find two inputs that gives the same output.
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#5192
  1. Each input will get a unique output. That output can not be reversed.
  2. Is used to write new transactions into the blockchain through the mining process. Inputs for the function are all of the most recent transactions along with some additional inputs relating to the timestamp and a reference to the previous block.
  3. If its not collision resistant than the system can be cheated therefor compromised.
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#5193

  1. Describe hash functions with your own words?
    Hash function is a function which takes an input of any length or object and in return creates a string of alphanumeric characters of fixed length. Length of hash depends on the algorithm you used such md5 , sha 64 sha256.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Every transaction is saved as a hash and address of the previous block is also saved in the block. Hash function and decentralized database are the two base pillars of blockchain.

  3. What does it mean when we say that hash functions need to be collision resistant?
    It means that no two different input can have same hash. Hash function should have such algorithm that every unique input should have unique output.

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#5194

  1. hash-functions make from every data-input a unique output.

  2. They are used to codify the input of a transaction and so produce a new hash as output.

  3. A hash has to be unique. Impossible to find 2 of the same.

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#5195

  1. Hash functions are functions that take a unique input to give a unique output. What makes hash functions different from regular functions is that the output or the hash canā€™t be used to identify the raw input.

  2. They are used to create Bitcoin addresses used to identify who the owner of a particular amount of bitcoin is that cannot be hacked into. In other terms, owners of bitcoin addresses will have a 256 digit binary code corresponding to their address which canā€™t be reversed back into the raw input.

  3. means that itĀ“s close to impossible to get different outputs for the same input in a hash function

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#5196

  1. Hash functions allow for text, numbers, or files to be converted through an algorithm into a string of numbers and letters that is always the same for the same input

  2. When a new batch of unconfirmed transactions is made on the btc network, all miners then try to combine that information with an input of their own in order to find an output that begins with a specific number of zeros

  3. To be collision-resistant means that it is extremely difficult to fins another input that could match the specified output

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#5197
  1. Hash functions take an input and use an algorithm that changes the input bits into a specific output of, say 32-bytes in the case of SHA256.
  2. Hash functions in bitcoin are used by taking the transaction data and running it through SHA-256, then taking that output with the header data and running it through SHA-256 and once again taking the output and running it through SHA-256 in what is called a merkle tree which makes it impossible to crack.
  3. Hash functions are considered collision resistant when there is no way to get the same output with two different inputs.
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#5198

  1. Hash functions are one way functions where each input produces an output.

  2. Hash functions used in mining blocks and eventually verify new transactions in bitcoin.

  3. A hash function is collision resistant if it is hard to find two inputs that hash to the same output.
    Collision resistance does not mean that no collisions exist however they are very difficult to find.

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#5199

a hash function is just a method of encrypting data i think.
sha 256 i guess. it makes it take 0 and 1 and turns them into unique patterns to ouput a specific set of sybols. like if i put hello world into a sha 256 hasher i will get ldsiruhfsieouhvcwu4h9837wm087cymf8wvuhnecu9nw4087hc084hdwhcx0uihb430uxyc3x8eha08wuxd8y3whc n0843rfjhf
make sense. encrypted means no find meaning
collision resistance is just the need for one input to equal one output no more no less i need to be able to have a unique output for each input thats the sucurity portion i think?

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#5200
  1. One-way functions with bit sensitive inputs that cannot be reconstructed from output to input/unique input, unique output.
  2. One way that comes to mind right off the bat is wallet addresses and seed phrases. Hash functions are also used to solve blocks as different transactions take place.
  3. Collision resistance basically means that no two inputs should ever be able to produce the same output.
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