Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#441

  1. a math equation that takes an input and creates a digital fingerprint as an output

  2. to makes sure none of the blocks have been tampered with

  3. we dont want duplicate transactions

1 Like
#442

  • Basically, it is an encryption of an input.

  • Hash functions are part of the block hashing algorithm used for new transactions to be written into the blockchain via mining. input = output of new transactions - written in the blockchain along some data of the previous block.

  • if I understand correctly, being collision resistant; means that the encryption of the input must be strong enough to basically make it infeasible to find what the actual input was.

#443

  1. Hash function involves a unique input and a unique output. It is a one-way function. The output could be deduced from the output, but not the other way round.

  2. In the bitcoin protocol, hash functions are part of the block hashing algorithm. The inputs for the function are the most recent but not yet confirmed transactions along with some additional inputs relating to the timestamp and a reference to the previous block.

    In bitcoin “mining” , the miners try to combine all of the inputs with their own input data in
    such a way that the resulting hash starts with a certain number of zeroes. By earning
    bitcoin through mining, you’re locking in the new transactions to the block, which is added
    permanently to the blockchain record.

  3. A hash function is collision resistant if it’s hard to find two inputs that hash to a same output.

#444

1 each will produce a unique output and is additionally safeguarded by being a one way function
2 hash function is used for each transaction and the record is kept in the blockchain
3 makes it impossible for any input to ever share the same output

#445
  1. Describe hash functions with your own words
  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).
  3. What does it mean when we say that hash functions need to be collision resistant?

1A, Hash functions are like a train on a single track with nowhere to turn around, and as soon as reverse is engaged an electrical diode is inserted onto the track.
2A, Data is sent thru a hashing process which gives only the originator (holder of the hash) returning a string of data that has been checked by many nodes. This string cannot be altered in any way without detection
3A, Collision resistance means two outputs detected (very rare)

#446
  1. Hash function takes an input string of any length and giving out an output of a fixed length.
  2. Hash functions are used in cryptocurrencies (like Bitcoin) by taking the transactions as input and running the hashing algorithm (SHA-256 in Bitcoin) which gives an output of a fixed length.
  3. Collision resistant means hash function should have more than one input which all used by that function to generate the hashed output. It is a property of cryptographic hash functions.
#447
  1. Hash funtion its a one way fuction like a non return valve and produce its own finger print .No hash its equal to another .Takes data and convert it to 256 bits.
  2. Hash fuction uses information from the last block/Ledger created and validate the new block/ledger with a new hash
  3. Hash fuction its collision resistance if it has two inputs with the same output because the inputs to a hash can have any length (Infinite) and the output its fixed lengh (finite).
#448
  • I think i made a mistake here, to be collision resistant is to basically make it hard for 2 inputs to have the same output.
1 Like
#449

  1. A Hash function is a complex mathematical equation that computes in alphanumerical terms when it computes an answer which is fundamental in the security of bitcoin

  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.

  3. A hash function is collision-resistant when the possibility of finding a collision is so low that it would require millions of years of computations. So despite the fact that there are no collision-free hash functions, some of them are strong enough to be considered resistant (e.g., SHA-256). So their purpose is complete security

1 Like
#450

You are talking about brute forcing sha256. Collision resistant means that no 2 inputs can produce the same output

#451

You are describing brute forcing sha256, collision resistance means that no 2 different values can produce the same hash (output)

#452

1.Any input converted to a hash
2. hash functions are used to add to the blockchain.
3. What i under stand is that a hash could have the same hash by two different people. just like the birthday paradox where two people in a large group are more likely to share the same birth-date.

1 Like
#453

  1. A hash function is a function that uses cryptography to convert a unique input value of any length into a unique output value of fixed length. It’s theoretically impossible to figure out the input value from the output value

  2. Hash functions are used to create public and private keys, digital signatures and Bitcoin mining

  3. A collision takes place when two different inputs produce the same output. If the hash function is strong enough to prevent this from happening it is considered collision resistant.

1 Like
#454

Hash functions are phrases or numbers inputted and computed to obtain a secure output which is a unique digital fingerprint.

Hash functions are used in Bitcoin by miners to make transactions secure on the blockchain. A private key can be inputted and outputted as a public address to make transactions secure, or a public address could be inputted and have a private address generated as output to facilitate sending and receiving transactions.

Hash functions need to be collision resistant for security and this means that whatever you input cannot get the same output if something else was inputted.

1 Like
#455

  1. A hash function prints out a unique output for every possible input. (until the unlikely event of a collision) When an input gets hashed it gets converted into a predefined length of bits. But the fantastic part about it is, that you can´t know what the input is based on the output. comparing the outputs of similar inputs is not usefull as the outputs are totally uncorrelated to each other. the best you can do to try and find out which input equals which output, is to just brute force until you found the same hash which can take you an eternity with today´s hardware.

  2. Hash functions in bitcoin are used to make sure no one can change a past transaction as other nodes and miners would be able to detect at which timestamp the hashes inside the chain began to be different showing where the fraudster tried to change any data.
    hash functions also are used in bitcoin mining as miners have to solve a random puzzle by hashing random inputs until an output is found, that meets the criteria, to be rewarded with new bitcoin.

  3. a hash function cannot be collision resistant because of the infinite ammount of unique inputs but the set number of possible outputs. a hash function can be considered collision proof if it simply is way to hard to find identical hashes. and by hard I am talking about millions of years using astronomical ammounts of proccessing power to find a single collision. (based on todays hardware capability)

1 Like
#456

  1. A hash function is a function that takes the input and gives an output with a fixed length. A certain input will always give the samer output, but the slightest interference in the input will result in a totally different output.

  2. Hash functions are used hash bitcoin transaction data and therefore create new blocks on the blockchain.

  3. A collision is when two different inputs create the same output. Because the output has a fixed length it is impossible to find a hash function that is collision-free. But it is important that it is as collision-resistant as possible.

1 Like
#457

  • 1. Hashing is generating a value or values from a string of text using a mathematical function. Aformula generates the hash, which helps to protect the security of the transmission against tampering.

  • 2. Hash functions are used to calculate public addressed from private keys and seed phrases, to find nonces and to calculate unique identifiers for every block.

  • 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; simply that they are hard to find.

1 Like
#458

1.) Hash function is the process of turning an input into an output that has 6 characteristics like collision resistance, quick comutation, determinism, pre-image resistance, small changes in inputs change the outputs, and being puzzle friendly.
Most importantly, it insures that an input can never be discovered based upon the output.

2.) Hash functions are used in Bitcoin to protect data through encryption. It allows data to be transparent without being accessible to manipulation.

3.) Collision resistance just means that two different outputs will never be the same.

1 Like
#459
  1. Describe hash functions with your own words
    A hash function is a mathematical calculation that takes input with variable length and produces a unique output of fixed length
  2. How are hash functions used in cryptocurrencies like bitcoin? Cyrpto has two keys, the keys are encrypted and the hash function allows the transaction to match the one key with the corresponding key. So the input is one key then hashed matches the output/key.
  3. What does it mean when we say that hash functions need to be collision resistant? It’s hard to find two inputs that deliver the same output.
#460

  1. Hash functions are one one way functions in where every unique input will out get a unique output of fixed length.

  2. Hash functions in cryptocurrencies are used to identify each unique transaction and also in the process of mining the cryptocurrency and creating new blocks.

  3. Hash functions need to be collision resistant in order to be considered secure. This means that it will be very improbable that two input values will result in the same output.

1 Like