Homework on Hash Functions - Questions

[JimKitzmiller]

Functions, Hash Functions, Cryptography

Describe hash functions with your own words

A hash function is software that takes an input and converts it to a long string of hexadecimal characters. A slight change in the input will produce a different output. It is impossible to go from the output back to the input.

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 ensure that each miner is coming up with the same data for a 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-resistant means that it is hard to find two hash function inputs that will yield the same output.

[hamy]

1 - it is a string of data, an input of data will create an output of data, a unique fingerprint. It is a oneway function and can only go from input to output. never the other way around. If something is changed in the input the output will change as well.

2- In the bitcoin protocol for example, 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 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 ).

[Vikthor]

1. Hash functions a Proof of authenticity. You can proof that the content of something is 100% the same you wrote or send to somebody. Without showing openly what you have written.

2. Bitcoin use hashfunctions for proof of authenticity between unknown participants of the network. And as a nonce in the successive blocks of the blockchain.

3. That means that it is very hard to find a second content which get as hashing result the same hash like a second one.

[Mehdi369]

1. Blending information or data, into a sort of id.

2. every transaction is hashed and writen in the blockchain.

3. it means that the hash function can’t give the same result twice

[Nat-hathai]

• Describe hash functions with your own words

Hash function is intricate mathematical equation (algorithm) to produce a unique finger print.

• 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).

With its tamper-free quality, hash function is pretty much the backbone to the concept digital currency like bitcoin as it facilitates correct and safe system. More importantly it helps create a network that is decentralized and cannot be manipulated by anyone. Hash function is used in the mining process and to create the unique finger print for transactions.

• 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).

Hash function is a unidirectional algorithm where inputs of information whether it is number, letters or pictures are mashed together through hashing resulting in a unique finger print. Any slight alteration in anyway in the original information will yield a different fingerprint. And it is impossible to reverse the hazing process to derive at the original inputs.

[Oprea]

1. Describe hash functions with your own words
   Hash function is a function that takes the input and pass it trough a set of one way mathematical equations to give a fixed length result called hash.

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 function are used to encrypt the initial data and secure the network.

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 funtion is “collision resistant” when no 2 or more different inputs can give the same output.

[Osgren]

1. Hash functions are special functions where each input has a unique output. No inputs can have the same output. Also you cannot figure out an input based on output. It only goes one way from input -> output.
2. Hash functions enable you to pass transactions anonymously
3. There is a probability that two inputs generate the same output but it is veryveryvery low. Basically impossible but not impossible.

[Chapin]

1. A hash function is a function that takes a unique input and give you a unique output. It is a one way mechanism that cannot be broken. It it is, it is no longer secure.

2. Hash functions in crypto are used to mining (PoW), transactions and validation. In the case of Pow, miners try to solve for the value to receive crypto as reward. In transaction, a has is used for anonymity, security (trust-less) and validation.

3. When a has function is collision resistant, it means that if is very hard or impossible for an input to give you the same output. Meaning, x=y and z=w. It cannot be the case that x=w.

[jelly]

1. Has functions are intricate mathematical algorithms that produce unique data when given unique data. They are linear one-way equations that only allow for outputs to be found from inputs and do not allow for inputs to be found from outputs.

2. BTC has functions are used to hash the transactions of BTC and then write them onto the next block of the chain.

3. They must not be able to receive the same alphanumerical outputs when inputting different data.

[Urs]

1. Hash functions calculate a fingerprint of the input data.
2. In bitcoin miners generate a fingerprint of the transactions as hashes.
3. Two blocks of input data must not result in the same fingerprint.

[alonsoalvaradojr]

1. Hash functions take an input and generate what is called a digest to store information more securely.
2. Hash functions are used to encrypt the transaction data so its secure and only the intended recipient can decrypt it.
3. In order for hash functions to be collision resistant there cannot be to separate inputs that generate the same outputs.

[DeyanG]

1. Hash function is a mathematical function that is a one-way function. When you hash an input you get output but you can’t identify the input from the output

2. Hash functions are used in the PoW. By solving a hash a minor receives the reward.

3. Collision resistance means that 2 inputs can provide the same output

[Bryan]

1. Describe hash functions with your own words

A hash function creates a unique output for a given input. However, it is a one-way only function: given an output it is impossible to solve for 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).

As proof of work the miners must solve for the input to a given output for a hash function. Doing this requires many tries and lots of computation.

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 H is collision-resistant if it is hard to find two inputs that hash to the same output

[Sysmaster]

Hash functions; Manipulate input data according to a mathematical formula. The output is unique to the input data. The hash if using say SHA-256 is one way. Meaning, a given input creates a unique output. However, given just that unique output, it is, at this time, impossible to derive the input data that created it. Also if I understand it correctly; a well designed hash will always create an output of X characters no matter the size of the input data.

A hash on a blockchain is created with each transaction, the inputs of that unique hash include the hash from the previous (I’m not sure of this) transaction or block, the private key of the initiator of the transaction plus the public key of the recipient and the transaction information.

Once accepted by peer nodes it is immutable.

Collision resistant; this link provides a succinct definition; https://en.wikipedia.org/wiki/Collision_resistance , however, after it states the clearly understandable; “a hash function H is collision-resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b where a ≠ b but H ( a ) = H ( b ).[1]:136” The remaining information is mostly a supersonic jet passing overhead …… It is not crystal clear to me what makes for good collision resistance nor the consequences. Hash functions; Manipulate input data according to a mathematical formula. The output is unique to the input data. The hash if using say SHA-256 is one way. Meaning, a given input creates a unique output. However, given just that unique output, it is, at this time, impossible to derive the input data that created it. Also if I understand it correctly; a well designed hash will always create an output of X characters no matter the size of the input data.

A hash on a blockchain is created with each transaction, the inputs of that unique hash include the hash from the previous (I’m not sure of this) transaction or block, the private key of the initiator of the transaction plus the public key of the recipient and the transaction information.

Once accepted by peer nodes it is immutable.

Collision resistant; this link provides a succinct definition; https://en.wikipedia.org/wiki/Collision_resistance , however, after it states the clearly understandable; “a hash function H is collision-resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b where a ≠ b but H ( a ) = H ( b ).[1]:136” The remaining information is mostly a supersonic jet passing overhead …… It is not crystal clear to me what makes for good collision resistance nor the consequences.

[Jared_Vizzi]

1. Describe hash functions with your own words.

Hash functions take a data set as an input and output a large, unique alphanumeric sequence. If any part of the input data is changed in any way, the resulting hash will be completely distinct. Also, once a set of data has been translated into hash, it cannot be reversed. In other words, the original data that created the hash cannot be discerned by looking at the hash.

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 by miners to attempt to solve algorithmic “puzzles” in order to add a new block to the blockchain. When they are able to produce a hash that is less than or equal to the target, their new block is added.

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 more collision resistant if it has more outputs than inputs. That is, it is less likely to produce the same hash from two different inputs.

[grapefruitgrape]

1. Hash functions are 1-1 functions, which means that each input has a unique output; two inputs will never yield the same output. Additionally, given the output of a hash function, one is not able to discern the input that created that output. You are only able to go from input —> output, not the other way around.

2. Hash functions are used in the mining of new bitcoins. A miner must find an input that yields an output with a certain number of 0’s. Since the miners cannot work backwards, this is a lot of work and processing power.

3. Collision resistant means that it must be very difficult to find two different inputs that yield the same output. Hash functions must have a unique output for each input

[Resonance]

1. Describe hash functions with your own words
   Hash functions are functions that convert variable size/length input data into a fixed size/length output string with a unique identifier.

2. How are hash functions used in cryptocurrencies like bitcoin?
   Hash functions can be used as a medium for monetary transactions, smart contracts (in the case of Ethereum), or universal translations (in the case of oracles, such as chainlink).

3. What does it mean when we say that hash functions need to be collision resistant?
   "Collision resistance is the property in which it is nearly impossible to find two distinct inputs that would “collide” into, or generate the same output.

[Cryptomonk]

1. A Hashfunction takes any given input data and converts it into a string of digits and letters.
2. Hash functions are used for the mining process.
3. It means that 2 diffrent inputs are not able to produce the same output.

[ElrondHalfelven]

1. Hash functions are outputs of functions that cannot be reversed, presumably.
2. They are used in cryptocurrency for security by analysing chunks of data and scaning it for any risk to security. Used in digital signatures, code signing certificates, biometrics and more.
3. Collision resistant means you cannot detect any two distinct inputs that would collide into each other or compute the same output.

[Victiinii]

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? (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).
4. string of data that is one input and is translated into an output leaving it in numbers and letters
5. BTC uses proto 256 for transcation and blocks
   3.collision resistance is a property of hash functions: a hash function H is collision-resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b where a ≠ b but H(a) = H(b)