Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#4179 
Describe hash functions with your own words

A process in which an input of data is scrambled up into series of numbers and letters.
This is a one way function and one cannot tell the input data from the output hash.

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).

SHA-256 is the hash function used to encrypt data. It works in a way where a has function will be connected to multiple blocks and to decrypt one block you would need to do same with the next and it goes on and on this way. It is nearly impossible to crack the data after six or more blocks have been confirmed.

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 no two different inputs should result in a same hash code as that would cause a conflict.

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#4180
  1. hash functions are the output in alfanumerical code ie sha-64 ,128 or 256 that is immutible. They cannot be changed & cannot be decrypted from reverse.
  2. hash functions in crypto are sha-256 in bitcoin. they are used for proof of work and consensus. highly secure b/c its almost impossible to guess b/c changing 1 char. changes entire hash output.
  3. collision, is the attacker. So we are trying to find the most secure hash function.
    the strong collision is harder to break than the weak one.
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#4181

1.A hash function is a one way function that gives a unique output for every unique input.
The output can only be derived from the input.You can’t derive the input from the output.

2.In regard to Bitcoin, hashes are used to verify and add new transactions to the blockchain.
Bitcoin transactions are hashed using SHA-256 (used in proof of work/mining) and
in each new block, the hash of the previous block is used as part of the input.

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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#4182
  1. Describe hash functions with your own words.

Hash functions are one way functions that produce a unique fingerprint (the output) for each given input. The mathematical calculation used to produce the output is so complex that it is impossible for any human to figure out how to go from output to input.

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

Hash functions are used to provide extra security through 3 different principles:

a. They are deterministic. Each input is connected to each output. As long as the input remains exactly the same, the output will not change. With the right structure, they are collision resistant avoiding the possibility of 2 inputs producing the same output.

b. They have a fixed output size. This depends on the type of hash function. SHA-256 hashes are always 256 bits. SHA-1 hashes are always 160 bits.

c. They are uniform. All hashes are distributed uniformly over the output space.

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

It means that the hash function is safe from a collision attack. In a collision attack, 2 inputs produce the same output.

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#4183
  1. Describe hash functions with your own words

Hash function is an algorithm that map data with variable length for data with fix length. The values returned for one hash function is called hash values/code hash/hash sums. The input data for an hash function can be anything, texts, files, images, videos, etc. Must be impossible generate the input data through the hash code done with the hash function. The hash code is represented in hexadecimal base. This code serves to ensure data integrity.

  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).

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

In bitcoin mining, the inputs for the function are all of the most recent, not-yet-confirmed transactions (along with some additional inputs relating to the timestamp and a reference to the previous block).

Changing a small part of the input for a hash function results in a completely different output. This property is crucial to the ‘proof of work’ algorithm involved in mining: to successfully ‘solve’ a block, miners try to combine all of the inputs with their own arbitrary piece of input data in such a way that the resulting hash starts with a certain number of zeroes.

Hash functions is used to for the wallet addresses, public keys and private keys.

  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).

Every time you put in a certain input on a hash function, it has to produce the same output and to be preimage resistant which means it cannot reveal any information about the input in the output.

A hash function has to be collision-resistant which ensures that it has to be impossible for two different inputs to produce the same output. It is the deterministic feature, pre-image resistance and collision-resistance that constitute the three most important properties of hash functions in the Bitcoin mining process.

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#4184

  1. Describe hash functions with your own words
    Hash functions are functions which are unidirectional, meaning the input cannot be deduced from the 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 functions are used in mining blocks to verify the integrity of received data. To solve a block miners try to combine all of the inputs along with their own data. This take a lot of computing and guessing.

  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).
    Collision resistant hash functions make sure that two different inputs will very unlikely have the same output.

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#4185
  1. Hash function it is a mathematical process that takes input of any size of data , perform an operation on it and in return will generate an output data of a fixed size and lenght , like a fingerprint .
  2. The hash functions for bitcoin are part of block hashing algorithm , are used to create new transactions into the blockchain network using mining process.
  3. Collision resistant means that it is very hard to find two inputs which merge the same output.
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#4186

1- A Hash function is based in mathematical calculation in which you insert a data (input) and the get a result (output), but the calculation is made in a progressive way and cannot be redone.
2-The hash functions in cryptocurrencies are used to calculate the block hashing algorithm which is obtained by mining and at the same time mantains the network active and secure.
3-Collision Resistant is when we have a function which the output cannot be obtained by two different inputs.

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#4187
  1. Describe hash functions with your own words.
    Hash function is a one directional function which takes the input, process it with cryptographic methods which are based on math, then gives back the output. There is no way to get back the initial input from the 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).
    For example, hash functions are used during the transactions for validating.
  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).
    Collosion resistance means that it is impossible to generate the same output from two individual inputs with the hash function.
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#4188
  1. Describe hash functions with your own words.
    Hash functions convert any sized input and converts it into a string of set-sized output ‘digital fingerprint’. This digital fingerprint can be altered drastically by something as ‘small’ as adding a period or a comma.
  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).
    Information from a block is hashed, the hash is then used to connect all the blocks. The hash of the previous block is inside the current block. To change or delete info in a block, all other blocks’ hashes must be recalculated too. This adds yet another layer of security on the blockchain.
  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 means that the likelihood of finding two inputs that give the same output is very unlikely, but not impossible.
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#4189

1.Hash functions are one-way functions, follow certain mathematical algorithm which transform input text to unique output.
2.used in mining and verify the transaction.
3. you can’t have same output from different input.

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#4190
  1. Describe hash functions with your own words.
    A hash function is a mathematical algorithm that converts a numerical input value of any size into another compressed numerical value of a fixed size.
  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash Functions are used for transactions into the blockchain through the mining process.
  3. What does it mean when we say that hash functions need to be collision resistant?
    A hash function is collision resistant if it is difficult to find 2 inputs producing the same output.
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#4191

  1. Hash functions are part of cryptography, and they are the mathematical equations that help a blockchain stay safe & secure. In Bitcoin this happens through SHA-256, because this hash function is able to produce a unique output (unique fingerprint) when given a unique input. What makes it so secure is that you can´t trace back to the original RAW data through the output (unique fingerprint)

  2. In Bitcoin hash functions are used in the process of mining. These functions are what the miners have to solve in order to confirm transaction and to receive the reward of solving the equation.

  3. What we mean when we say that hash functions need to be collision resistant is that, it´s extremely hard to find 2 inputs that will produce the same output in a hash function. If we could find 2 inputs that produced the same output, than the technology wouldn´t be safe because we could get to the input from the output.

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#4192

  1. A hash function is a computational algorithm that takes characters as input of any length and format, and the output is a fixed length hexadecimal string that will always be the same for the same input. The length of the output is always the same for all inputs (i.e. 256 bits for SHA-256). The output can therefore be described as a “signature” for the input data. Any change to the input, will generate a different signature. The algorithm is “one way” which means it is near impossible to compute the input from the signature.

  2. Hashes are used to sign the blocks, in blockchains to make sure they can never be changed or deleted. Blocks are the additions to the ledger which contain transactions. Each time a block is added, it contains a hash of the previous block, and of the whole block chain. So if a block were changed or deleted, then the hashes would become invalid. Hashes are also used for PoW (mining) and PoS (consensus).

  3. Collision resistant means that the function used to generate hashes should be resistant to producing the same hash for different inputs. If different inputs produce the same hash, then this is called a collision. The hash function is more resistant to collisions the greater the number of possible hashes that can be produced by the function. SHA-256 can produce 2^256 possible hashes - which are sufficient combinations to be considered to have good collision resistance.

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#4193
  1. Special functions that give a unique finger print.
    2.You can hash transaction data to get a unique identifier the same applies to block header to get a block hash and public keys to create bitcoin addresses.
  2. collision resistant means no 2 inputs should have the same output (unique fingerprint)
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#4194

1. Describe hash functions with your own words

The hash function is the function that creates a unique representation (signature) of input data. It is done in such a way that it is just one way. Input can’t be recreated from the output of the function. The result is created as a 256-bit long number, which is conveniently displayed as series of hexadecimal digits, where one hexadecimal digit represents 4 bits. That is why a result is 64 hexadecimal digits long.

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 is used to uniquely signs one block of data in cryptocurrency’s blockchain.

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 means that it is very hard to find two different inputs resulting in the same output. If that would be easy to find and index, breaking the function and recreating input based on output would be easier and therefore not secure.

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#4195

  1. A hash function is a one way function that takes an input and produces an output.

  2. the hash function us used to hash transitional data. In mining, the hash function is used to create a difficult way for individuals to create blocks by guessing the input that created the output.

3.collision resistant means that it is highly improbable that two inputs can create the same output

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#4196

  1. Describe hash functions with your own words
    Hash functions are complicated mathematical one-way functions that receive any kind of data as input and produce a unique key (fingerprint) of the data as an 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).
    Produced hashes are crucial to the ‘proof of work’ algorithm involved in mining. To successfully solve a block, miners try to combine all of the inputs with their own arbitrary piece of input data so that the resulting hash starts with a certain number of zeroes.

  3. What does it mean when we say that hash functions need to be collision resistant?
    Collision resistance in hash algorithms is the principle that the hash will never be the same for different inputs.

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#4197

  1. Hash functions are one-way mathematical equations within which each unique input gives a unique output. Unlike standard functions within which knowledge of the output can allow us to determine the input, knowledge of the output of a hash function will not enable us to determine its input.

  2. In cryptocurrencies like bitcoin, hash functions are used to keep the blockchain upon which the cryptocurrency 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. In essence, a hash algorithm is a 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. This size can vary depending on the hash function in use. Standard and popular sizes include the 64-bit, 128-bit and the 256-bit.

  3. When we say that hash functions need to be collision resistant, it means that it needs to be hard to find two inputs that hash to the same output; that is, two inputs x and y where x does not equal y but H(x) = H(y).

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#4198
  1. Describe hash functions with your own words
    Is a computation that takes an input string and creates a unique hexadecimal output for each unique 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).
    Is used to generate private keys from public keys, blocks are given a hash output which are then validated by other nodes.
  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).u research information on your own, that’s how you learn best).
    A collision resistant hash function is one which has no equal outputs with non-equal inputs i.e. all outputs are completely unique given different inputs.
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