Homework on Hash Functions - Questions

[Taishi_Nammoto]

1. Describe hash functions with your own words

Hash functions gives unique outputs based on inputs.
You cannot calculate or guess the input based on 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).

It is used for transaction records.

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 means preventing to find same output based on different inputs.
Hash function always gives the same output if you input the same content.

[SuperiorBlocks]

Describe hash functions with your own words
Hash functions are one-way taking a unique input and producing a unique output.

How are hash functions used in cryptocurrencies like bitcoin?
to pass transaction information anonymously, for password verification, signature generation, and verifying file and message integrity.

What does it mean when we say that hash functions need to be collision resistant?
When it’s highly unlikely for the hash function to produce the same output from two or more different inputs.

[Rahul_Kumar]

@ivan

Homework on Hash Functions - Questions

1. Describe hash functions with your own words
   [Ans] Hash functions are advanced functions that provide a unique digital fingerprint for any kind of content. It takes data of any length and gives output in 256 bits. It has the unique property that it’s one-way. we can get go from input to the same output for a given content, but we cann’t derive input from a given 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).
   [Ans] These hash functions are used for transaction records as way to verify and validate that the transaction data has not be altered in chains of block. In blockchain the blocks of transactions uses hashes and signature and these blocked are interlinked along with hash of previous. If any block is tampered/altered by any node, it can be break the codes in other blocks.
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).
   [Ans] It basically means two input should never result in same output hash

[JComes]

1. A hash function is where data or an input, in our example a sentence, is converted into an alphanumeric string that represents that exact input. If the input changes slightly, a new string is created. This i think falls under provenance and immutability

2. If all transactions are recorded on the blockchain using hashes each transaction will have it’s own irreversible string that represents that specific transaction which can be identified and traced to it’s origin.

3.Collision resistance means that two different inputs will never, or it would be extremely unlikely, produce the same output.

[prakashmech1]

1. Hash functions are like for a unique input it has unique digital output achieve through SHA256 algorithm. This is linear or unidirectional, means its not possible to decode the output value to retrieve the input and this proves to be more secured.
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, not-yet-confirmed transactions along with a reference to the previous block. To successfully ‘solve’ a block, miners try to combine all of the inputs with their own in such a way that the resulting hash starts with a certain number of zeroes.
3. Collision resistant in hash function means the output hash has the same value for 2 different input

[Mirthis]

1. An hash function is a function that given the same input always produce the same output but where is not possible to derive the input from the output (one way).

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’re used as a fingerprint for each block. The block content and pointer to previous block are hashed and when the hash meet a specific criteria the block is mined and added to the blockchain. Everyone can recompute the hash and verify the block hasn’t been tampered with.

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).

We mean it’s really hard (not impossible) to find different inputs that produces the same ouput

[rebeccawatkins16]

1. Hash functions is a mathematical function that converts a numerical input value into a compressed numerical value.

2. Hash functions are used in actions such as authentication, document signing, and validation.

3. Hash functions is computationally infeasible to find two colliding inputs.

[Jedi06]

Describe hash functions with your own words

A hash function is a specialized function used for data storage, retrieval, & security. A hash function takes an input (data or a message) and returns an output (hash value), usually as a string of bits. A good hash function is fast and easy to compute, difficult to reverse, and collision-resistant.

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 take transactions and turn them into a fixed string of letters and numbers.

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 if it is hard to find two inputs that hash to the same output

[skleinheny]

Hash Functions:

1. Describe hash functions with your own words
   It is a function which outputs an hexadecimal phrase calculated based on the input information. It doesn’t vary if the input is the same and is very different even with very slight changes in the input. It is not possible to find out the input based on 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 within blockchain blocks. A miner needs to find the correct hash output based on the previous block in order to validate a new block and write it in the blockchain. This complex calculation is the proof-of-work mechanism.

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 should be almost impossible to get the same output with two different inputs.

[edagili]

1. Hash functions unidirectional functions where each input is unique and produces unique outputs.
2. Hash functions in bitcoin turns text inputs into a string of bytes with a fixed length and structure. They are always one way and cannot be reversed.
3. Collision resistant means two different inputs not getting the same hash.

[nisaac21]

Hash functions are one-way mappings that create a unique, fixed-sized output for any size input.

1. How do cryptocurrencies use hashing?

2. Cryptocurrencies use hashing in order to validate a block. Each block has certain identifiers (version number, timestamps, hash pointers, etc.) that are hashed together to create the output. By solving the hash, a miner validates the block and is rewarded in coin.

3. Miners solve complex math equations nad must come up with a hash that is less than or equal to the target hash.

4. How is a hash function collision resistance?

5. Collision resistance is a property of a hash function where it is hard to find an a,b where a ≠ b and H(a) = H(b). This is to say that finding two unique inputs that hash to the same output is extremely difficult, making the hash function collision resistant.

[JonBal]

1. Hash functions allow someone to provide a unique input and get a unique output. It is impossible to figure out what the input was from the output.

2.Hash functions in bitcoin are used to pass transaction information anonymously. They are used for generating public keys and block hashing.

3. A hash function is collision resistant if it is difficult to find two inputs that hash to the same output; That is to be H(a) = H(b)

[DelBobs]

1. Hash functions are code for coding a message or transaction Where changing anything in the original message a space, comma, letter etc… will alter the code and the original message can’t be decoded. To encrypt the inputted data.
2. Hash functions in crypto currencies are used to mine coins to build blocks, by taking any size of data then performs operation to obtain output of a fixed size. The hash must all be the same length. Thus all same size blocks on the chain.
3. So it will be hard to find two inputs that hash to the same output. Each output of pre-processing passes into its own hash function which gives the hash output. This output method reduces hash collision for unique results. Reducing chance of collision for entire process of hash outputs.

[cotts31]

• Describe hash functions with your own words
  Hash functions take inputs of any length and converts them into outputs of a fixed length

• 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 Crypto to ensure privacy and security over the network. They are also used to generate public keys and block hashing

• 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 for two distinct inputs, the output of the hash function should not be the same.

[NWcryp]

Homework – Hash Functions

Describe hash functions with your own words
A hash function is a algorithm to encrypt data into a code that can not be decrypted.

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 being used in crypto to verify transactions and add to the security, bitcoin miners have to use very high computing power to solve the equations and validate the transaction.

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 resistance means that it’s hard to find 2 inputs that hash into the same output.

[Leonardo_Almeida]

1. Describe hash functions with your own words
   => A hash function is a one-way function that maps inputs of arbitrary sizes to a fixed-size 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).
   => Miners have to find the correct input (i.e. the correct bit sequence in the block header) to earn the block reward. In order to be accepted by the network, the SHA-256 hash of a block’s header must be lower than or equal to the target .

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 means that different inputs are unlikely to generate the same output (for a given hash function).

[Si13]

1. Hash functions are one way. An input will give a unique output but can not be reversed
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, not-yet-confirmed transactions (along with some additional inputs relating to the timestamp and a reference to the previous block).
3. Collision resistance is the property of a hash function that it is computationally infeasible to find two colliding inputs.

[EdvardsVitols]

1. functions where the input cannot be deduced from the output as opposed to regular functions where by knowing the output the input can be calculated.
2. Computers use sha-256 hashing algorithm to turn incoming data into fixed outputs. The transactions are stored in blocks and each block has a hashpoint that points to the previous block.
3. Each unique input must have a unique output

[Amrit]

1. Hash functions give a unique input and unique output (unique fingerprint). It is a one way function and if anyone were ever to figure out how to go from output–>input then BTC would break.

2. Bitcoin uses hash functions for creating addresses out of public keys, and to add blocks of transactions into the blockchain.

3. When a hash function produces the same output for two different inputs, this is called a collision .

[CentralizedChad]

1. Hash functions are functions where each unique input will produce a unique output. You can’t deduce the input based on the output, but you can deduce the output based on the input.

2. Hash functions are used in mining new transactions on the chain. Inputs contain metadata of transactions that haven’t yet processed. Also used for private keys in public wallets.

3. When it’s impossible for one input to hash multiple outputs.