Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#161
  1. They are like “the most reliable and restrained fingerprint” of every input.
  2. They are used to create Merkle trees in order to make the data easily accessible.
  3. It means that for the most part, two inputs will have its own unique hash. On this regard, we should take into consideration “The Birthday Paradox”.
#162

A hash function is a mathematical equation that encrypts data into a designated amount of digits which resemble the data stored.

Hash functions are used in bitcoin to create each block on the block chain. sha256 algorithm used in bitcoin is a gpu mined hash function with a 10min est block time of creation.

Hash functions being collision resistant equates to the idea that 2 similar bits of information will not return similar hashes. another words if block 2 is n+1 and block 2 is N+1 the hash will be completely different with the messages being very similar. although they occur they are meant to be rare. Some are also know as “provably secure.”

#163

  1. Hash function is a way to create a cryptographic output for data on the input side.

  2. The hash function is used in bitcoin to convert all the information in the transaction into a hash which will be added to the block.

  3. The collision resistant is a property that explains how hard it needs to be to find two different inputs for the same hashed output

#164
  • Describe hash functions with your own words

A hash function is like a fingerprint for a string of data. Data is converted by a hash function into a unique series of numbers.

  • 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 the liked list joining a block to its predecessor. The current block contains a hash of the previous block.

  • 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 happens when two different inputs are hashed and result in the same output.

#165

1)A hash function takes an input of any length and returns it to an output of a fixed length. It is important to note an output can not be converted back into an input it is a one way process.

2)Hashing is used by miners but also to encrypt all transaction data which is part of what makes bitcoin so secure.

  1. We must ensure that different inputs cannot generate the same output therefore creating a “collision” in Bitcoin this is very unlikely because the hashing algorithm used is SHA-256 which has a fixed 256 bits length thus making it pretty much collision resistant.
#166
  1. Describe hash functions with your own words
    String functions that once computed can not go back
  2. How are hash functions used in cryptocurrencies like bitcoin?
    As hash pointers, which basically store the address and hash data from the precious block.
  3. What does it mean when we say that hash functions need to be collision resistant?
    Two different inputs will never be the same
#167

  1. A hash function is a unique input that produces a unique output. It is a one-way function that can never be revised from unique output to unique input.

  2. Hash functions are used by miners when searching for a new block in the blockchain.

  3. Collision resistant means it’s difficult to find two inputs with the same output.

#168
  1. Hash functions provide unique outputs from unique inputs - a fingerprint for data. The SHA-256 hash function is very secure because the input cannot be determined from the output. The fixed size of the output is also a big part of this security because all data - regardless of how small or large - will be hashed at the same length.
  2. Bitcoin and other crypto currencies use hashing to secure transactions and create new blocks via mining.
  3. It means that the hash function should be difficult enough so that it is infeasible to find two inputs that equal to the same output.
#169

1 Hash functions are digital finger prints that goes from input to output, it is a one way function.

2 Hash functions are used in crypto currencies because once the transaction has been entered onto the blockchain it cannot be altered, it’s secure and trustless.

3 Collision resistant means that it is virtually impossible to find two inputs that hash to the same output.

#170

1,It’s a one way encryption that can’t be reverse engineer.
2, to encrypt private keys.
3,it means two different inputs can’t create the same output

#171

  1. Describe hash functions with your own words
    Hash functions are digital fingerprints. Each input gets a unique fixed length output.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions is bitcoin are used as cryptographic protection to ensure that all transactions are real and no fake bitcoins can be created. Miners calculate the input (previous transaction data+time data and new transaction data) to add new blocks onto the chain which confirm transactions.

  3. What does it mean when we say that hash functions need to be collision resistant?
    That the likelihood of two inputs producing the identical output is mathematically infeasible

#172
  1. Hash fonction consist of creating a unique digital fingerprint output from a unique input.
  2. Transactions in bitcoin are signed and completed by the unique digital fingerprint output. And because the hash function only goes from input to output that show that results can never be altered
    3.“collision resistant” because it impossible for two different input to give the same output.
#173

1 Hash function is data going in and getting a unique fingerprint and going out without being able to reverse the process.

2 A hash function is used as a unique finger print that connects the blocks together in the blockchain.

3 Collision resistant means that two different functions shouldn’t come up with the same hash.

#174

1 Hash function is data going in and getting a unique fingerprint and going out without being able to reverse the process.

2 A hash function is used as a unique finger print that connects the blocks together in the blockchain.

3 Collision resistant means that two different functions shouldn’t come up with the same hash.

#175
  • Hash functions take an input and produce a number output
  • Hash functions in Bitcoin are used to produce and authenticate information and the creation of new blocks on the blockchain.
    Collision resistance refers to the difficulty in producing the sam output from the input.
#176
  1. Describe hash functions with your own words.

Wow. Let’s try. Hash function basically is some complex calculation that takes any input and turns it into a deterministic output with a fixed length. It is supposed to be unreversible (although apparently some hashes have already been cracked).

Any small change in the input will change the output completely.

  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).

Ok Just searched a bit. It’s still too much for my mind. Ohhh. What I can kind of get is that the hash functions is used in a few ways in bitcoin. It is used to give a good challenge for the miners. And also it’s probably used for the blockchain itself as a means to keep the chain going without putting all the data all the time but keeping the connection with the “hashing fingerprint”. That way all the transaction are connected in a way that any small change will be noticed easily. Something like that?

  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).

Collision resistant means that two hashes outputs to different inputs are hard to find. Beacuse the hashes can generate a specific number of outputs (and not more than that), and the number of inputs is much greater (or is it infinite?) - then there must be different inputs that give the same output. The question of collision resistant is - what is the probability of that happening.

#177
  1. Hash function takes input and provide unique output. And it is almost impossible to calculate back the input from the output
  2. Hash function is used to record new transaction in the blockchain through the mining process.
  3. Collision resistant means the status that it is unlikely that 2 random input gives same output through a given Hash function.
#178

  1. Hash functions take input data (of variable length) and run it through an algorithm to create an illegible output data of a fixed length. This Hash of the data is near impossible to reverse calculate.

  2. Bitcoin uses Hash functions for various features of its code. Hashing is used to proving ownership of unlocking keys on a public ledger without revealing private key data. Hashing standardizes varying input data to a unified manageable data size. Hashing of current and previous blocks is used to ensure data integrity as any slight charge would create a completely unrelated Hash.

  3. A collision resistant Hash function infers a low likely hood of identical output Hashes being created from different input data. Implementation of a high minimum entropy nonce greatly increases the possible Hash outputs by orders of magnitude.

#179

  1. Hash functions are a system where a certain input produces a certain output. The output is the unique fingerprint of the input. It is a one way function, whereby input can produce an output and not the other way around.

  2. Bitcoin uses a hash function whereby the transactions are the input which then goes into the hashing algorithm (SHA 256) to give an output of a fixed length bit string. The hash contents are then added to a block to go onto the blockchain.

  3. Collision resistance in hash functions means that it is highly unlikely for one hash output to duplicate another hash output. Each input has a unique hash, so the output string will never duplicate the output string of a different input.

#180

  1. Describe hash functions with your own words
    Each unique input produces a unique output (unique fingerprint).

  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).
    In a blockchain, the hash of a previous block in a sequence is a tamper-proof sequence. Because as a function of the design, a hash is very sensitive. So, to change any variable of any one of the hashes in a given block would cause a domino effect. Subsequently, it would alter all of the previous transactions in the block. Blockchain hashes are deterministic because the input data will produce the same result each time.

  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 highly unlikely to get two inputs that will produce the same two outputs.