Homework on Hash Functions - Questions

[FOSSCrypto]

1. Describe hash functions with your own words.

A hash is a function that produces a digital output or fingerprint from an input.

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

Unconfirmed transactions along with previous transactions are the input information that miners use to perform numerous computations to guess the solution for the next block in hashing.

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

Hash functions need to be collision resistant as in they need to be hard to find two inputs that hash or produce to the same output.

[Tomaage]

1. Describe hash functions with your own words

Hash functions takes an unique input and produces an unique output. The same input will always produce the same output. But there is now way to 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).

The input to the hash function is all the recent, not yet confirmed Tx and some other stuff needed. To get these Tx into the new block you need to use massive computer power to try to guess the answer with your own arbitrary piece of input data added that gives you the required hash answer that the protocol is asking for

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).

a hash function is collision resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b such that H(a) = H(b).
Every hash function with more inputs than outputs will necessarily have collisions. Consider a hash function such as SHA-256 that produces 256 bits of output from an arbitrarily large input. Since it must generate one of 2256 outputs for each member of a much larger set of inputs, the pigeonhole principle guarantees that some inputs will hash to the same output. Collision resistance doesn’t mean that no collisions exist; simply that they are hard to find.

[Jack126]

1. they give an unique output on a certain input via a 1-way calculation.

2. They are used to verify the transactions on the blockchain and to mine the blocks which gives out rewards in the form of BTC.

3.It means it hard to find two inputs that hash to the same output.

[TylerGardner]

1. Describe hash functions with your own words
   Each unique Input gives a unique Output aka Fingerprint of the 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).
   (to the best of my limited knowledge, here’s what I sort of understand, i think)
   Hash functions are used as a way of verifying multiple items of a previous block, such as time, nonce, merkle tree, etc, in addition to new info given for the new transaction. These inputs are sent as a hash themselves and translated into a 256 bit hashed output. These hashes ensure that the original information is kept private, like a password, while computing the same output that the other blocks in the chain have computed in order to achieve a “consensus” or the same answer.
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 is to ensure that two inputs will not get the same output

[angnimasherpa]

1. Describe hash functions with your own words

• Hash function is a computational function that computes the given input value/parameter and transforms each unique value into a different output value.

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 is used to send the transaction anonymously and only the intended party can see the full transaction data. The mining also computes to get a unique value in each block which starts from 18 zero values that must be done through hashing as well.

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 refers to the case where no two input has the same output.

[Padma-Suta]

1. A Hash function is taking raw data and translates it into Alphanumeric strings of different sizes, which are all unique in themselves and can therefore serve as a “digital fingerprint”.

2. Hash functions enable Bitcoins to run the consensus mechanism and be verified as a unique and irreversible unit, for each bitcoin has their very specific digital-fingerprint (required for PoW). Also the “blockchain hashing algorithm” is required for mining and new transactions.

3. (Took me a while to get my head around it - but here we go)

a.) If I understood correctly, then every hash is meant to produces a unique output.
b.) It is based on mathematical equations, that generate an output, which are according to the Hash that has been used of a particular size, like SHA-256 (256-bit sizes)
c.) Looking at the example a ≠ b and H (a) = H (b), I don’t know why it troubled my brain, but I understood that in words it means: A and B are different inputs(numbers, letters novels, whatever), but they produce the same Hash, that is not meant to happen.
d.) The above c.) is so rare that it’s not even taken into consideration, imagine you have numbers and are formulation as many varieties of passwords as possible. With 1 digit, got 1 variable, with 2 you got 4 options, 3 - 9, 9 - 81 and so forth. Now add letters to that and then for example say size of the numbers and letters are 256. How many potential passwords could you create from that ?

I am quite new to most of this stuff, but I assume (hopefully understood this right here) the hash to be even more variable and extensive then my simple example.

Every hash function has it’s unique number and collusion resistant simple means, that the technology and maths used herein are highly secure and flawless in terms of encrypting. The chance for the same potential outcome from different inputs is ridiculously small.

[patrickbrouwer]

@ivan

• Describe hash functions with your own words
• 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).
• 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).

1. Hash function takes an input and gives the output as a unique string of data (fingerprint) that is one-way. The output cannot be reversed back to the input.

2. To anonymize transactions, and to verify that every transaction is unique.

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

[jordanv]

1. Hash functions are a one way encryption method, In which one can not use a key to decode the data back to its original state.

2. Hash functions are the core component of crypto mining. miners process blocks and attempt top generate a hash with x amount of leading zeros. (Dependent on current difficulty)

3. hash functions need to be collision resistant so that we reduce the chance of multiple miners creating the same output hash from different inputs.

[Pawel_Jez]

1. Hash function is digital fingerprint. Its purpose is to ensure data integrity and authenticity. It is one way function from input to 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.
3.    Hash functions need to be collision resistant what is needed for very low probability of two inputs generating the same output hash.

[Magnos]

1. Hash functions it a way to encryp the data and make it unique and inmutable must to yo can only go ahead. The data who produce the hash, can’t be reconstructed from the hash.
2. It’s the way to be a transparen ledger and can garantize the value of your wallet and the chagen of value must to transacctions.
3. Means that a kid of input has only one hash output.

[Nadia]

• Describe hash functions with your own words

It is irreversable deterministic function which encripts any information in to a fixed size alfanumeric code.

• 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 write new transactions into the blockchain through the mining process.

• 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 two bitcoins with the same hash are better to not exist.

[ralphwilburnjr]

1. Describe hash functions with your own words
Hash functions are unique, digital fingerprints that cannot be reverse engineered.

2. How are hash functions used in cryptocurrencies like bitcoin?
Cryptographic has functions are widely used in cryptocurrencies to pass transaction information anonymously. It is also used to mine bitcoin.

3. What does it mean when we say that hash functions need to be collision resistant?
In cryptography, collision resistance is a property of cryptographic hash functions: a hash function H is collision resistant if it is hard to find two inputs that hash to the same output.
A collision is where two different messages hash to the same output.
Collision resistance is important when you’re relying on hash functions to ALWAYS map two inputs to two different values.

[btcbrandon]

1. Hash functions are computer translations of computer files into fixed size strings of characters using mathematical functions.

2. Hash functions are used in cryptocurrencies to encrypt data (digits, letters, or media files) on the blockchain that are only accessible with a private and public key. In the case of cryptocurrencies all of the information (time stamp, amount, address) is hashed into a transaction ID. The blockchain “computes” blocks that store Tx IDs and then the blocks are hashed. With each consecutive block the information on the previous block in also hashed – thus creating a secure, immutable, and transparent network.

3. Collision resistance is the difficulty at which it is possible for two inputs to have the same outputs (AKA: given 2 inputs, input a and input b, where h(a) = h(b) )

[Dawid_Lynch]

1. Hash functions are sentence inputs that are turned into a 64-bit code of a digital fingerprint.
   2.Hash functions are used as digital signatures as well as message authentication, they are also used by mines to prove that thy indeed received transactions correctly.
2. This means that It is very difficult or nearly impossible to find two inputs that produce the same output result.

[SGG]

1. is sha 256 equivalent
2. they are used in proof of work
   3.i’ll wait to learn on this one

[Jorgevargas]

1. Describe hash functions with your own words

They are mathematical functions that convert any text, number or image into a hash that’s standard in size.

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 allows to make information anonymously. In Bitcoin it is used the Sha-256 hash function in its algorithm. There is a signature algorithm called “Merkle Tree” used to encode blockchain information more efficiently and 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).

It means that is it impossible to two transactions that gives the same result and that every single one of them will be independent, so no collision of information is possible. In reality, it is possible for a collision to exist, but the time it will take is so long that it does not matter

[adoni]

1. Describe hash functions with your own words
   They are algorithmic operators “take X convert to Y” the same way a vendine machine takes $1 and gives you 1 coke, but much more complex mathematically.

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).
   Consensus is achieved through nodes agreeing on what the next block should be added. Who of the 100000s of nodes gets to add the next block to the chain? Nodes compete with each other for the ability to do that: they have to solve a random computational problem based on hash functions. Since they can’t hack the hash function, they have to do trial and error to solve the problem. This requires computational effort, and it is this computational effort that secures the blockchain. Game Theory + the unhackability of the hash functions make this possible.

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).
   Two different inputs cannot have the same output.

[IrishDevlin90]

1. A hash function is a one-way function where each input produces an output or digital fingerprint.
2. On the bitcoin protocol, hash functions are used to write new transactions on the blockchain. This is done through the mining process, where the input of a function is the most recent one and the not confirmed yet transaction. To solve the block miners will try to combine all the inputs along with data of their own to get an output starting with zero.
3. Collision resistant means that it is nearly impossible to find two inputs that produce the same output in a hash function

[Vanhait]

1. Describe hash functions with your own words
These are a one-way function when given the output it is impossible to determine the input.

2. How are hash functions used in cryptocurrencies like bitcoin?
Hash functions are used in bitcoin mining. All of the not-yet-confirmed transactions along with some other data are run in the hashing function until the hash starts with 18 zeros.

3. What does it mean when we say that hash functions need to be collision resistant?
Collision resistant means that two inputs to the hash function do not yield the same output.

[MichaelAudire]

1. Hash functions are a one-way function that takes unique string of data input and returns a fixed length output.

2. Hash functions are used to create digital signatures and link together blocks.

3. Collision resistance is the property that any two inputs should not hash to the same output.