Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#3839

  1. Hash functions is hashing an input to an output data of fixed size that gives you a unique “signature” You can only go from an input to an output and not the other way round.

  2. In Bitcoin, the hash that is used is the sha 256 algorithm. You use this in creating addresses and public keys.

  3. Collision resistant because you will never get the same result/signature using 2 different inputs. And you can not reverse it. Every small change you do, will completely change the result/signature.

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#3840

  1. It’s a one way function (you shouldn’t be able to know the origin of the output) that generates a unique digital fingerprint, for each input. And the hash function has a fixed output size.

  2. It is used to protect every transaction on the Blockchain. Bitcoin uses SHA-256 which difficult to brute force.

  3. To avoid that two different inputs have have the same output.

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#3841

  1. Hash functions are algorithms that scrambles data into a unique omelette every time. The omelette never tastes the same and you can’t put all the eggs and the ingredients back together!

  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. A hash function is collision-resistant if it is hard to find two inputs that hash to the same output.
    The harder they are to find, the more cryptographically secure the hash function is.

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#3842
  1. Describe hash functions with your own words - a function that converts an input into a unique string, it’s unidirectional, you cannot go from output to reproduce 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). - they are used to secure/codify the transfers of value; used in mining, they are meant to solve the titles of the inputs, based on the outputs, when solved a block is created.
  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 the inputs are unique and that each of them generates a uniques output. collision resistant refers to the unlikely situations when two different inputs generate the same output.
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#3843
  1. hash function is a one way function where an input is scrambled and each unique input will give a repeatable unique output.
  2. each transaction serves as the input (together with time and previous trasactions) and the hash function helps to encrypt the information. it also helps to form an incentive system where bitcoin miners guess the correct output for a reward.
  3. it means the probability of two input getting the same output is close to impossible
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#3844
  1. Hash function is a unidirectional function where an input gives a desired output.
  2. Hash functions are used to write transactions and miners then pick up some of these transactions and use them as input to calculate an output.
  3. Collision resistant is that the output will remain different or have a low probability of being similar when using multiple inputs.
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#3845

1.) With a hash function u can change any kind of text or digits into a hash. With this hash u have an unique fingerprint of the text. If anyone change the text, the output of the hash it completly diffrent.

2.) Hash funtions in Bitcoin are used to find a new Block in mining. Also to generate Public and Private Keys.

3.) Every has function who have more inputs than outputs are not collision resistant. Once a hash function have more less inputs than outputs its very unlikely to find a collision.

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#3846
  1. A hash function produces a unique output, or digital fingerprint, for every unique input it receives.
  2. BTC miners solve increasingly difficult hash functions to add new blocks to the blockchain in exchange for compensation. The inputs of the hash functions include previous unconfirmed transactions and time with allows them to be unique and unidirectional.
  3. Collision resistance means 2 different inputs cannot produce the same hash.
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#3847
  1. Describe hash functions with your own words
    A hash function is a mathematical method to convert the input, which could be no. text or words into a fixed-length alphanumeric string.

2.How are hash functions used in cryptocurrencies like bitcoin?
The Hash function is used to write new transactions into the blockchain through mining.

3.What does it mean when we say that hash functions need to be collision resistant?
It means that collision resistance holds if it is practically impossible to find two inputs that hash to the same output.

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#3848
  1. hash functions are one way functions AND which have a unique output for a particular input
    It is up until now been impossible to reverse the process and egt the initial input from reverse engineering the output/hash
  2. Used to mine unique hashes. Mathematically almost always unique hashes.
  3. It should be almost impossible to create two of the same exact hashes, to prevent for example a double transaction. Link in the double spending problem case.
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#3849
  1. It is a mathematical function that can compress data of any size into a compressed fixed array value.
  2. They are used to compress transcation data as well as help mining new bitcoin by creating unique hashes specific to newly mined blocks.
    3.Collision resistant means two inputs will not generate the same output through the same hash function.
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#3850
  1. A hash function is a one-way function, for every unique input the function produces a unique output.
  2. Hash functions are solved by miners to add new transactions into the blockchain.
  3. It means that it is practically impossible to find two inputs with an identical output.
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#3851

  1. Describe hash functions with your own words: A hash function takes an input and converts it to a unique set of characters for the output. The same input always equals the same output. The output can not be reversed to find 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). Hash functions are used to create a fingerprint for the data in a transaction and the hash is also used by the miners in the proof of work verify and add the transactions to 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). Two different inputs will never create the same output.

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#3852
  1. One way function that converts any input into a fixed unique output.
  2. THe hashing functions are used to tie the blocks in the chain. Also used in the mining process, with certain difficulty, in order to generate the hash of the block.
  3. It must be hard to find same output to different inputs.
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#3853
  1. Describe hash functions with your own words
    Answer: generate an hast that converts an input of letters and numbers into an heximal 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).

Answer: A hash is a function that converts an input of letters and numbers into an encrypted output of a fixed length. A hash is created using an algorithm and is essential to blockchain management in cryptocurrency.

  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).

Answer: Collision resistance is the property of a hash function that it is computationally infeasible to find two colliding inputs. This property is related to second preimage resistance, which is also known as weak collision resistance.

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#3854
  1. Hash function give each unique input a unique output or unique digital fingerprint. It’s impossible to go from output to input. When a small change is made to the input a new unique output is created that can’t be linked to the original file.
  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.
  3. collision resistant means not getting the same hash output from input.
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#3855

-Hash function is like digital fingerprint of the input
-hash functions are used to mine bitcoin and so, veryfying transactions
-Collision resistance means that its nearly impossible to find 2 inputs that gives you the same output

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#3856
  1. Describe hash functions with your own words

Hash functions are the process of changing an input into a complicated output that would be hard to reverse.

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

  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).

When a hash function is collision resistant it means that you shouldn’t be able to get the same output from 2 different inputs.

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#3857

  1. Hash functions are a digital fingerprint for a specific input. There’re different hash functions that provide different cryptographic results based on the number of bits or fixed size used within the hash function.

  2. Hash functions are used for security purposes in identifying transactions on the blockchain. It’s used as a validation mechanism. If someone wanted to change the ledger or double-spend a transaction, they would have to change the hash in all previous blocks, or be able to recreate the initial input, which is virtually impossible to do.

  3. “Collision Resistant” is a property of the hash function, and a hash function is said to be collision resisant 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). The “pigeonhole principle” guarantees that some inputs will hash to the same output. Collision resistance doesn’t mean that no collision exist; simply that they are hard to find.

Pigeon Principle - In mathematics, if n items are put into m containers, n > m, then at least one container must contain more than one item. E.g. if you have 3 gloves, then you must have at least 2 right-handed or left-handed gloves.

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#3858

  1. A hash function is a function in which you cannot use the output to determine the input. Output is encrypted.

  2. Hash function algorithms are used during mining of new bitcoin

  3. Collision resistance means that no two differing inputs could create the same out(it is not random, its all math based with reason)

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