Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#2612

  1. Describe hash functions with your own words
    Hash function means its a one-way streak from input to output.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    In Bitcoin, hash function is used to create addresses, private and public keys. Transforming transactions which can be recorded as hashes in a ledger.

  3. What does it mean when we say that hash functions need to be collision resistant?
    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 where a ā‰  b but H ( a ) = H ( b ).

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#2613
  1. Describe hash functions with your own words
  • Hash function translates an input into the same output as a result.

  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).

    • Bitcoin translates transactions with SHA-256 hash algorithm into outputs. This is secure since its not
      possible to find the source transaction from the function output and efficient , since we always get a
      fixed output no matter how long its the input.

  2. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).

  • It means that it is not possible to find the same output for 2 different inputs of the function. So the output of a hash is always unique like a fingerprint.
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#2614

  1. Hash functions is where you insert an input and generates a unique output like a fingerprint.
    The output will be in a 16 bit base format with letters and numbers using SHA256 .

  2. Hash functions in bitcoin are used to write new transactions into blockchain through mining.

  3. its means that its needed so makes it harder for the possible attacker to break the function.

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#2615

Transaction id is the transaction hash and a merkle tree is a tree of hashes whose leaves are the txids. The root of the merkle tree is calculated from these txid which is then used in the mining process to generate the block hash. :slight_smile:

#2616

  1. Hash functions provide a digital finger print (output) to any input entered. To be efficient it can only go from input to output and not the other way.

  2. Hash functions are used in the algorithms used to write transaction into the blockchain through mining.

  3. It means that it needs to be able to have a different output to every input entered. If we have the same output for 2 different input we have a collision.

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#2617
  1. A hash function is a function used to encrypt inputs. They are one-sided functions made to make the output of the function unreadable, in order to protect the input from the public.
  2. Hash functions are used in cryptocurrencies to protect private keys. the hashed versions are called public keys, its what allows the ledger to be public.
  3. When a hash function is collision resistant, it means no 2 inputs will have the same output. This is a very important feature to have in a hashing function.
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#2618

1.Each unique input generates a unique output. If only one character is changed, the entire output changes. Importantly, this function is a one-way function. That means you donā€™t come back from the output to the input.

2.Hash function SHA-256 (Secure Hash Algorithm with 256Bit -> 64 characters) used as proof of work in the Bitcoin mining algorithm, creating addresses like private and public keys

  1. A hash function is collision-resistant if it is hard to find two inputs that hash to the same output
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#2619

1/ the hash function is a way to encode data in such a way that its fingerprint is unique and impossible to know the information that it contains, having only the output

2/ It is used to store information in such a way that it is transparent, secure and accessible to all as long as certain conditions are met

3/means that the hash function has the characteristic that it is almost impossible to obtain the same hash from 2 different inputs

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#2620

A hashing function encrypts digital information only one way, it is very unlikely for anyone to be able to revert a hashed string to its original state.

The hash function is used in the creation of new blocks. The previous blocks hash is combined with the contents of the new block and appended a nonce. If the new hash is lower than the difficulty level it is approved by the network and added to the blockchain.

It is possible for the hash to generate the same output for two different inputs. Though extremely rare it can happen. To be collision resistant means that the likelyhood of this to happen is close to impossible.

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#2621

Hash functions are not used to derive public keys, for that the elliptic curve is used. However the address is a hash of the public key. :slight_smile:

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#2622
  1. Describe hash functions with your own words

Hash function can take any string input and convert it to a unique string with a fix amount of characters depending on the hashing algorithm. the hashing function most perform with 100% consistent results for each input.

  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).

hash function been used all over the cryptocurrencies world from wallet address or seeds, private keys, block indexing and hashing, and for mining algorithms puzzle solving.

  1. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).

ā€œCollision resistanceā€ meaning that thereā€™s no two (or more) inputs that will produce the same output.

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#2623
  1. Hash functions are a way to secure inputs but creating complicated and original outputs that cannot be traced back to what the input was. A key security component of Bitcoin.
  2. Hash functions turn inputs into unique and complicated outputs in order to secure data on the blockchain.
  3. Collision resistance refers to hash function inputs that never have the same output. The harder it is to duplicate outputs or inputs then the more secure the system.
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#2624

  1. A function that creates a unique output from a unique input and is near impossible to crack (relate the output to the input)

  2. hash functions are part of the block hashing algorithm which is used to write new transactions into the blockchain through the mining process.

  3. Collision resistance is important because it provides security and stop attackers from being able to figure out the input from the output

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#2625

Homework on Hash Functions - Questions

  1. Describe hash functions with your own words
    Bitcoin has funtios are one way computation functions that have unique outputs
  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).
    Each transaction has its own hash
  3. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).[Collision resistant is when an input has an identical hash output, ie its very important in cryptography that this does no occur
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#2626

  1. Hash functions operate by taking an imput, putting it through an algorithm to get a 256 bit output. This is a one way process and it is deterministic. Meaning that if the input is the same you will get the same output, change the input and the output changes drastically.

  2. In bitcoin, the cryptographic hash function SHA 256 is used in mining to create merkel trees and to generate new addresses.

  3. we mean that two different inputs should not equal the same hash output. If thisi is the case, the inputs are presumed equal. However while we need hash functions to be collision resistant, they are not always. Although, this number is infinitely small because of the high bit output (256).

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#2627

Hash functions are one way information encoding mechanisms. A hash function takes information and generates a hash which is like an encrypted version of the original information. Any chan he in the input will completely change the output.

They are used in bitcoin for mining and recording transactions. They use the new inputs along with the previous hashes to encode a new block for verification.

Collision resistance refers to the probability of two inputs generating an identical output. This needs to be extremely unlikely for the network to remain reliable.

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#2628

Hash Functions are used to verify data and make sure the hashes match to know that any data has not been altered or changed.

How are hash functions used in cryptocurrencies like bitcoin?

Hash functions are used in cryptocurrencies by having miners guess the digital input that can create the hash target and solve the problem. The miners must try many different combinations of input and the first miner to answer the problem correctly wins of matching them.

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

Hash functions need to be collision resistant because if it isnā€™t, it defeats the purpose of crypto as someone can easily break the function with little effort. Being collision resistant makes it very hard for anyone to attack the network easily, which keeps the blockchain in tact and correct.

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#2629

  1. Describe hash functions with your own words
    A has function is a function which works only one-way from input to output. Each unique input of a hash function gives a unique output. A unique digital fingerprint.

  2. 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. 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. What does it mean when we say that hash functions need to be collision resistant?
    Collision resistant means that it is very difficult to find two inputs that produce the same output.

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#2630

  1. Describe hash functions with your own words
    A hash function is a function that utilizes various properties in order to secure the data stored in the blockchain and guarantee itā€™s immutability by producing a ā€œdigital fingerprintā€ like string of code. This function has several properties to ensure data going from input to output can not be reversed 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).

Hash functions are used in cryptocurrencies like bitcoin by using a hashing algorithm (for instance BTC uses SHA-256) which produces an output of fixed length. This ā€œdigital fingerprintā€ creates a Merkel Tree, helps to speed up the rate of transactions by being able to follow a ā€œhash trailā€ to cut down on time to find out if a particular transaction belongs in that block or not and in the mining process, in both creating new blocks and ā€œnoncingā€ new hashes to the proper target difficulty.

  1. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).

Collision resistance is the idea that in almost all instances, each input will have its own unique hash, and the probability of two inputs creating the same hash is almost impossible.

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#2631

  1. Describe hash functions with your own words
    A hash function is like a mathematical formula that gives you an output by giving it an input. Itā€™s a one way function, so canā€™t figure out the input just by knowing the output.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    In bitcoin the transaction are taken as input included some other information like timestamp and previous hash and run through the 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?
    Means most time each input will have its own unique hash. It is infeasible that two different inputs and their respective hashes are equal.

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