Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#1969

Highly unlikely. It means that two inputs don’t result in the same output.

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#1970

  1. Describe hash functions with your own words:
    Is a one way function which transform input text to an unique output.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    They are used to encrypt the transaction data and only the intended recipient can decrypt it, which makes it very secure.

  3. What does it mean when we say that hash functions need to be collision resistant?
    It means each input is transformed to an unique output and the probability of two different inputs transforming to the same output its almost impossible.

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#1971

  1. Hash functions are a way to encrypt strings of data or inputs of any size into a cryptographic hash that has the same output that can’t be altered or change, and also can’t be discovered by working backwards from the output.

  2. Bitcoin is a digital ledger for hash functions that store data and provide security and mathematical traceability. These hashing functions are then used for new transactions mined on the blockchain.

  3. Collision resistant means two different inputs creating the same output is highly unlikel.

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#1972

  1. Letters and numbers prescribed certain numbers and alphabets used to code and for inputs in the blockchain

  2. Hash funcitions are used to write new transactions into the blockchain mining process as a part of a algorithm.

  3. Hash functions being collision resistant refers to them not having the same output coding wise once they are entered as a function. While not impossible, it is extremely unlikely it will happen.

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#1973
  1. A hash function is a function that produces a unique output for an input and it is infeasible to retrieve the input based on what the output is.
  2. Hash functions can be used to secure transactions by making it infeasible to to retrieve the input from the output.
  3. When a hash function is collision resistance it means that two parties making a transaction will not both generate the same hash.
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#1974
  1. Fixed lenght output with any input
  2. Hash Function are part of the block hashing algorithm which is used to write new transcation into the blockchain.
  3. Collision resistant means very low probability of two inputs generating the same output hash
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#1975

A hash function computes a digital ‘fingerprint’ of the input value of the function.

Hash functions are used in cryptocurrencies for:

  • Writing new transactions into a blockchain through mining

Collision resistant means the likelyhood of H(A) = H(B) is extremely low. So low that it is safe to assume in this case that A=B.
3.

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#1976

  1. Hash functions are mathematical equations applied to inputs to generate unique outputs.

  2. Hash functions are used to create unique digital fingerprints of data which form the bases of new blocks.

  3. Collision resistance refers to the high unlikelihood of coming up with the same outputs through hashing, i.e., it is very unlikely that any different inputs will result in the same output.

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#1977
  1. Describe hash functions with your own words

A hash function is a one way conversion of an input of any length to a unique output with a fixed length.

  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).

Cryptocurrencies uses a transactions as input and store the unique output on the blockchain

  1. 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 its must be very hard to have two inputs that have the same output.

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#1978

  1. Describe hash functions with your own words- A hash function is a one way function, meaning that you put in an input and get an output. You can not get the input from the output though. You get a digital fingerprint pretty much.

  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 which gives an output of a fixed length. It is also used in mining bitcoin as well. Hash functions are part of the block hashing algorithm which is used to write new transactions into the blockchain through the mining 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).
    It means that for the most part that each input will have its own unique hash. Functions need to make sure that multiple inputs will not have the same hash.

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#1979

1- A hash function is a one way input to output function which converts an input into a “digital fingerprint” output that represents the input, using an algorithm such as Sha-256
2- Hash functions are used to ensure every transaction is immutable, as even the slightest change will change the hash, and since the hash contains the date of previous hashes, it would also need to change all those hashes.
3- Collision resistant means it is infeasible (if you use a proper algorithm) to have two inputs hash to the same output.

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#1980
  1. A hash function has two key properties. First, for each unique input, it produces a unique output. Second, It is like a one way street in that, the input will yield the output but the output cannot be used to obtain the input.
  2. Hash functions are used to secure bitcoin by providing a means of obtaining the output of a hash function easily, whilst guarding the input.
  3. Each input must deliver a unique output such that the hash of A will not deliver the same result as the hash of B.
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#1981

  1. Describe hash functions with your own words
    Answer: Hash functions are one way type of function where each unique input will produce a completely unique output or digital fingerprint. The properties of cryptographic hash functions are definitively deterministic, quick computation, pre-image resistance, small changes in the input changes the hash, and collision resistant.

  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).
    Answer: In cryptocurrencies like bitcoin, hash functions are used in the particular hashing algorithm SHA256. This hash function takes an input of data of any length and gives an output of a fixed length in order to encrypt the data. This hash is then stored on a block on the blockchain.

  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).
    Answer: When we say that hash functions need to be collision resistant, we mean that two different inputs computed through the same hashing algorithm will produce two completely different outputs, or its own unique hash, most of the time.

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#1982
  1. Hash functions are “one way” functions that give a fixed length (256bits for SHA256) output for every input. They are used as a sort of digital fingerprint that can be verified even it is practically impossible to deduce a given input from a given output with our current technology and computing power. This fingerprint feature is used to check data integrity since the slightest change in the input would drastically change the output.

2.Hash functions are used in crypto to check the integrity of blocks in the chain, which makes something like Bitcoin highly secure and difficult to fudge transactions and other data on the chain. Miners use hash functions to solve complex math problems in order to find blocks and get rewarded in BTC.

  1. Collision resistance means that its rare but not impossible that two different inputs could give the same output hash in a hash function.
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#1983
  1. Describe hash functions with your own words

It gives input a unique identifier

  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).

To give each coin a unique identifier with the ledger.

  1. 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 needs enough bits that collision is infeasible.

@ivan
@IvtechUser01
@Khary

#1984

Coins don’t have unique identifiers, that would kind of make them nonfungible, NFTs can have a unique identifier :slight_smile: do you know another use case for hash functions in blockchain?

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#1985

Coins don’t have unique identifiers, that would kind of make them nonfungible, NFTs can have a unique identifier :slight_smile: do you know another use case for hash functions in blockchain?
Makes it so you can go from input to output but not output to input.
@Alko89

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#1986

  1. A hash function is similar to a function, but distinguished by the fact that it is practically impossible to move from output to input.

  2. Hash functions are used in a couple ways. First, computing the hash of a new block is what creates the “work” in mining, thus giving BTC and other coins value (costs of computing power, electricity, etc.). Second, the hash function guarantees that no information in previous blocks could be changed, giving cryptocurrency the trait of immutability.

  3. A hash collision occurs when two separate inputs give the same output. If the hashing mechanism is not collision resistant, then fraud is very possible. It would be like someone stealing social security information or one’s fingerprints! Not good!!!

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#1987

  1. Hash functions are one way. Any change in inputs results in different hash value. Same inputs always gives same hash value.

  2. Hash function used in BTC:

  • hash of current block is created by hashing previous block’s hash value with newly added transaction information.
    -miners are supposed to generate n number of 0s in hash value to successfully mine a block.

3)collision resistant means very rare chance of 2 different inputs generating the same hash value.

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#1988

  1. A function that takes as input a unique string of bits (X) of any length and that produces an output that is another unique string of bits (Y) of constant length and for which it is infeasible to find the original input by just using the output. Hash(X) = Y for which there is no ReverseHash(Y) = X.

  2. Hash functions are used to link the nodes of the blockchain together and preserve the integrity. Because each node stores the hash of the previous node, if you alter a single node you need to rebuild and rehash all the following nodes in the chain. This ensures the integrity of the blockchain.

  3. Collision Resistant: It means that for 2 different inputs the hash function will not return the same result.

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