Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#5392
  1. Describe hash functions with your own words

Hash functions are functions that are capable of accepting inputs and returning a unique output for each unique 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).

It is used to pass transaction information anonymously which helps to achieve the consensus mechanism of Bitcoin.

  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).

This means that Hash functions should always produce a unique output for every unique input.

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#5394

  1. Hash functions are functions that take in an input and produce an output, but has no reciprocal function. That is, given an output to a hash function, there is no function that can take you back to the original input value.

  2. All transaction information (as well as the hash for the previous block) for a particular time period is hashed. This hash becomes the new block on the blockchain.

  3. Collision resistant is the measure of how likely two or more hash inputs will generate the same hash output.

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#5395

1.Hash functions are one way functions where each unique input produces a unique out put
2. Hash functions encript the data so its secure for transactions to be made
3.It is very dificult to find tow inputs that produce the same output in a hash function

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#5396
  1. Describe hash functions with your own words.

Hash function is software algorithm that produce a unique digital fingerprint, a sort of computational digital signature. It’s the result of any given data inputted. Any altercation to the original data will give a different hash output. Each input data will result in a distinct hash signature. Hash functions is one way mechanism. Any output data cannot be used to reverse and recalculate the back to the original raw data. Only input data can generate the output hash.

  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 64 bit string of numbers and letters is a cryptographic result of SHA 256 is called the hash. A hash function is a type algorithm used in bitcoin called SHA 256, created by NSA, it’s function is sort of a universal translator, in which any data of any size can be input and translate them into 64 alpha numeric strings (can be 128 bit or 256 bits as well).

It’s imperative that the bitcoin blockchain is safe and secure. Each block on the blockchain is cryptographically linked together through the hash function, which unique and cannot be altered. If anyone attempts to alter it the current hash will change.

In order to Mine bitcoin successfully one needs to keep solving a cryptographically puzzle in while in competition with other miners for one’s block to be apprehended to the blockchain network. There are financial rewards and incentives the miners to mine.

  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).

The hash functions need to be collision resistant in order to avoid to different inputs to produce the same output.

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#5397

  1. Describe hash functions with your own words.
    Each unique input gives a unique output, a fingerprint. When you change something you get a different fingerprint. You can go from input to output, but you can’t go from output to input. It’s a one way function.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    They are primarily used for generating public keys and block hashing. Block hashing is a core concept of Bitcoin mining.

  3. What does it mean when we say that hash functions need to be collision resistant?
    Collision resistance is the property of a hash function that it is computationally infeasible to find two colliding inputs.

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#5398

  1. Describe hash functions with your own words
    Hash functions are an input of data that will be recorded and given its own unique output. The output will have a unique # matching that particular data entry.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions are used when new wallets are generated and the private keys that go along with the ownership of the wallet. These unique sets of numbers show property or ownership of the wallet and funds.

  3. What does it mean when we say that hash functions need to be collision resistant?
    Collision resistance is computationally infeasible to find two colliding inputs. It is very hard to get the same output for two different data entries.

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#5399
  1. Hash functions are functions that take an input and create a unique output.
  2. Hash functions are used to create wallets and assign them a wallet ID. Hash is also used to encrypt transaction data so it is secured. They are also used to aid the consensus process.
  3. To say hash functions need to be collision resistant means that hash functions need to be able to consistently create new unique outputs for every input. Essentially, if two identical outputs were created, the function could be compromised.
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#5400

  1. Mathematical equations designed to give unique irreversible outputs.

  2. They are used to encrypt input information into blocks.

  3. It is computationally difficult to find matching Inputs.

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#5401

1). Hash functions are adding a unique set of numbers or letters that will produce a unique set of binary linear non-directional output. Input a set of numbers I will get a digital finger print of that number. The input can be any amount of numbers/ letters or different lengths, but the output will have a fixed length. The output is called the hash. Also, you can never go from output to input, hash function is a one-way function. There are many hash functions, but for bitcoin the algorithm is SHA 256. The only way to recreate the input value from a complex hash function is to brute-force search all possible inputs, but this is nearly impossible.

2). In the Bitcoin protocol, SHA 256 mining is used to solve a mathematical formula. Hash functions use data structures in computing tasks, that check the integrity of the message and to verify the information. Hash functions add security to the data/information to make more difficult to see the information being sent or received. Cryptographic hash functions provide three properties: They are collision free, can be hidden one way transaction difficult to guess input from output. Also, difficult to select an input that will provide a pre-fined output. Password verification can also be stored as a hash function, along with signature generation and verification, which means you can verify signatures to authenticate digital documents and messages. Three algorithms are used: key generation algorithm, a signing algorithm and a private key algorithm all produce a digital signature. Merkle trees is a technology used in cryptocurrencies, as kind of digital signature.

3). Collision resistant means it is very hard to find two same inputs to produce the same output.

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#5402

  1. A hash function takes an input of digital information of any length and creates an output of a fixed length. This is a one way function.

  2. Hash functions are used to secure transactions, create cryptographic public and private keys, and are also used for block hashing.

  3. Two different inputs will not create the same hash function output.

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#5403

  1. They are functions that, given a set of inputs, generate another output of fixed length.

  2. They are used to create a digital footprint, therefore unique, in the processing of data or transactions.

  3. That the same output cannot be generated from two or more different inputs.

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#5404

  1. Describe hash functions with your own words- Creates a unique input that can never be reversed, can go from input to output but never 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). They are used in cryptocurrencies to pass transactions information anonymously and to pass information securely

  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).
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" 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" not all has functions have collisions as well.

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#5405
  1. Hash functions can convert strings into data.
  2. Hash functions is used for security purposes.
  3. Because it is impossible to get the save hash function twice.
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#5406

Hash functions take data and morph them into unique strings of numbers and letters. There is no way to go back from this output to the input.

In the case of Bitcoin, the hash is based on the SHA-256 function that creates unique alphanumerical outputs of 256 characters. The outputs are used to ‘save’ the transactions in blocks, and are also used to link the blocks together. If someone tries to change a block the slightest, the SHA-256 output will be radically different.

Hash functions need to create unique outputs. If two different inputs led to the same output, there would be a ‘collision’. Therefore, ‘collision resistance’ means the degree to which a hash function creates unique outputs.

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#5407
  1. Describe hash functions with your own words

Hash Functions are used to make the blockchain secure. They take different type of input and ensure the output always has a uniform length. This helps with security as hackers won’t be able to correctly guess the length of input.
It is also a linear way interaction between input and output in that a generated output can not be reversed to reveal the input.
Finally, different inputs can never result in the same or even similar outputs. A slight change in an input will result in a totally different output.

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

Hash functions are used to pass transactions in the blockchain anonymously. They help to secure the blockchain and to prevent double transaction - selling the same bitcoin to multiple people. (I don’t understand the process well enough to write about it. I will wait for better lessons from the course materials.)

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

it simply means no two separate input can result in similar output. The output will always be unique as long as the input are not exactly the same.

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#5408

A1. A means of encryption
A2. To encrypt the transaction in a way that it can be validated but cannot be read inside.
A3. Hash value shouldn’t be same as a previously generated hash with different data.

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#5409
  1. Hash function represent input of any kind of data and as output delivers a unique string of numbers and letters.
  2. Hash function in Bitcoin is used to produce the private and public key that represents the input data and its validated by the miners using protocol called Proof of Work.
  3. Collision resistant means that is almost imposible to get same output for two diferent sets of data.
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#5410

1 a hash function is something that takes any type of input and gives back a series of digits and letters as output.

2 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 transactions

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; In some proof-of-work systems, users provide hash collisions as proof that they have performed a certain amount of computation to find them. If there is an easier way to find collisions than brute force, users can cheat the system.

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#5411
  1. A hash function provides a unique fingerprint and can be used to confirm data integrity
  2. Hash functions are an integral part in keeping the Bitcoin and other crypto currencies safe and secure.
  3. Hash functions need to be collision resistant in order to ensure that 2 individual inputs do not produce the same output
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#5412

  1. Describe hash functions with your own words
    Any form of input data gets converted with a type of hash algorithm (i.e. SHA256) into a hash output which represents the input data. This is irreversible and can be verified for any changes of the input data.

  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).

Once a new BTC block has been mined it is hashed through SHA256, this is then used to verify and check that previous blocks have not been tampered with or changed.

  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).

A Hash collision is when 2 strings of hash input result in the same output. Meaning that you could duplicate an output hash but the inputs are different, apply this to a block on the blockchain and you could technically change the transactions of the block unnoticed. Hash functions need to be resistant to this to secure the input and output data, minimizing the chances of fraud/mistakes etc. Therefore collision resistance means the degree to which a hash function creates unique outputs

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