Homework on Hash Functions - Questions

[Alko89]

@SheepBoss

Additionally they randomly hash a number which selects the miners who are rewarded payment in bitcoin.

Miners look for the right number and the winner takes the price (block reward), not the other way around

[Alko89]

@jamesvoraw

Hash functions are used in Bitcoin and other crypto currencies to create a pair of public and private wallet addresses.

We don’t use hash functions to generate keys. The private key is a random number and from it we derive the public key using elliptic curve. However we do hash the public key to get the address

[Ernesto]

1 is a one way function where you can go from input to output but not the opposite it also generate a fingerprint or unique id for each input
2. Bitcoin used SHA-256 and basically create a unique output using the data from the input
3. when we say a hash needs to be collision resistance means that every input will get a unique output
you can never had 2 inputs with the same output this will broke the BTC blockchain

[Dreamer]

I really like how you formulated your answers - informative yet succinct! Thank you!

[mesoto]

• Describe hash functions with your own words

one way traffic. for a unique input it will output a unique hash.

• 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).

bitcoin is a combination of multiple hashes that gives it unique characteristics. in blockchain technology the subsequent block mined consist of hash information that contains attributes of the block before it.

• 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)

this means that the output of H(a) will never equal output of H(b) unless a =b.

[wafflemakr]

@Ernesto

Bitcoin used SHA-256 and basically create a unique output using the data from the input

Hi there! correct, but do you know where does bitcoin uses this? In which process?

[AlexandreJun]

1. Describe hash functions with your own words

Are functions that when applied the input, gives a single unrepeated output for every imagined input, almost, because infinite cannot be described.

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 guarantee that the past is immutable, since the data is resumed easily during the process.

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).
   because everytime it collides (give the same answer to different inputs) it can weaken the antifragile nature of the cryptic part of crypto coins.

[Bitcoinstache]

1. Describe hash functions with your own words
   Hash functions are functions where one input of string data (any size) will be converted to a unique fixed length of output data. It is infeasible to derive the input string data from the unique output data of the hash function.

2. How are hash functions used in cryptocurrencies like bitcoin?
   Hash functions are used in many ways with cryptocurrencies like Bitcoin. A few examples how Bitcoin uses hash functions are; First, Bitcoin derives the address by inputting the public key (with additional steps) through two hash functions SHA-256 and RIPEMD-160. Next, in the Bitcoin blockchain the notion of “mining” requires miners to brute force a partially known input, derived from the latest state of the blockchain, through the SHA-256 hash function to reach a hash target thus discovering the complete correct input and being rewarded in Bitcoin. And last transactions, hashed transactions, and combined hashed transactions of a block are input through the SHA-256 hash function until a root hash is achieved allowing for the formation of Merkle Trees.

3. What does it mean when we say that hash functions need to be collision resistant?
   When we say, “Hash functions need to be collision resistant,” we mean that the input for the hash function must be infeasible to reuse. If the same input is used twice or more through a hash function the same output will be reproduced each time. This would be detrimental to the blockchain as per the purpose is to transfer and secure value.

[oligcoonpan]

1. Hash function is a one way function that transfers input data in to a unique output. It cannot be reversed.
2. Hash functions are used to encrypt data, and only the recipient can decrypt it
3. It means that no 2 different inputs should form the same output.

[VICBTC]

1. Describe hash functions with your own words
   **Hashing is generating a value or values from a string of text using a mathematical function and cannot be reversed.

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 transactions are taken as input and run through a hashing algorithm bitcoin uses SHA-256) which gives an output of a fixed length.

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).

** hen we say that hash functions need to be collision resistant , we mean that it is infeasible to find two colliding inputs (two inputs that have the same output when both of them are hashed). The minimal requirement for a hash function to be collision resistant is for the length of its result to be 160 bits.

Why are non- collision - resistant hash functions considered …

https://security.stackexchange.com/questions/215836/why-are-non-collision-resistant-hash-functions-considered-insecure-for-signing-s

The security margin of that function is much severed than of collision resistant ones. An attack that one day seemed unfeasible, or a hash function that was “only” not collision-resistant , not-too-long after may be further broken with a new discovery, forcing you to need to change it real quick.

Which cryptographic hash algorithm has the highest …

https://www.quora.com/Which-cryptographic-hash-algorithm-has-the-highest-collision-resistance?share=1

For those who don’t know what collision resistance is, please read here Collision resistance. As we know (from the above link) for a hash function which produces output of length n bits, the probability of getting a collision is 1/2^n/2 (Due to Bi…

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; that is, two inputs a and b such that H = H, and a ≠ b.[![|16x16]

[jamesvoraw]

Thanks for that info. I believe that I have better understanding now.

[Alko89]

@oligcoonpan

Hash functions are used to encrypt data, and only the recipient can decrypt it

You can’t really decrypt the hash. You can only verify that the hash was derived from the said input

[1207]

1. Describe hash functions with your own words
   R: is a mathematical function to encrypt data.

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).
   R: Has functions are key in cryptography which is one of the key characteristics of a cryptocurrency like bitcoin. Hash functions allow for the submission of data in a secure way.

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).
   R: it is a feature of a hash function where it is difficult to find two inputs that hash the same output.

[ANV81]

1. Describe hash functions with your own words
   A hash function turns any type of input into a set size of bits represented by a unique string, sort of like a digital fingerprint.

2. How are hash functions used in cryptocurrencies like bitcoin?
   It’s used to create keys, hash transaction data, and create blockchain identifiers into individual blocks which also allows for chaining and the mining process to verify transactions securely.

3. What does it mean when we say that hash functions need to be collision resistant?
   The unique outputs created, although possible to generate the same string using different input, has a very very low chance of being replicated, which prevents hash collision.

[Ipitos]

1. Take data, convert it into a “code” and if someone has the same code, they match and give access
2. Transactions are taken in and hashed, and then they are connected with the hash to the next block in the blockchain
3. The same hash code cannot occur when doing 2 different inputs

[Adrie567]

1. making a unique fingerprint of some data or file

2. hash in bitcoin are used to make data unchangeable

3. collision means two blocks with the same hash which means the same data. the resistance is the ‘nonce’ random data/text string, added to the hash string and than hashed again until the difficulty is met. this random nonce makes collision almost impossible.

[elrider]

Describe hash functions with your own words.
All inputs are one of a kind which can only give a one of kind output, also hash functions can only be from input to output and not in reverse.

How are hash functions used in cryptocurrencies like bitcoin?
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.

What does it mean when we say that hash functions need to be collision resistant?
collision resistant’s hard to find two inputs that hashes same outputs.

[oligcoonpan]

Thanks !

[Taran]

1. A special function that allows that when something is inputted, it has its own unique output (fingerprint).

2. Hash functions are used often by miners, who adjust the signiature data until the hash starts to turnover a greater profit.more importantly hash functions enable more security on the network. As blocks contain hashes of the previous block and so adjust accordingly it becomes a lot easier to verify the chain against hashes.

3. Collision resistance, is where 2 entities cannot be represented by the same hash. The practically infinite combinations means it will be a very long time before the possibility of a hash clash

[GraVeddieMusic]

1. When a string of text or value is entered into a hash function you will get a set result different from the original value and the chance of guessing what the result is considered infeasible.

2. The hash function is used for security when a bitcoin is sent through the network the SHA-256 algorithm is used to protect the key from getting hacked or tampered with while a transaction is being transferred or stored.

3. The odds of using the “brute force method” of hacking the encryption is considered infeasible because the amount of outcomes to be guessed one at a time would need quantum computing and technology that has not been developed to even try. There is a High Min-entropy because of the amount of outcomes are infeasible unlike the “Birthday paradox”