Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#3598
  1. It is a mathematical function that takes input and produces output.

2.They are used in chaining blocks together. Every block has a hash of the previous block in it.

  1. There cannot be two same outputs with different inputs.
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#3599

  1. Describe hash functions with your own words
    A hash function is a one way function. A hash function can only go from input to output. Each unique input will produce a unique output.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions are a 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?
    A hash function is collision resistant if it is hard to find two inputs that hash to the same output.

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#3600
  1. Hash functions are unidirectional mathematical formulas which create unique results based on input parameters.
  2. Hash functions are used to create the block chain by miners.
  3. A collision is when the output is the same for two different inputs. In the SHA256 algorithm, this is extremely unlikely.
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#3601
  1. A hash function are one way functions where each input produces an output or digital fingerprint.
  2. Each hash is unique to the relevant input. Should the input change in any form the data will produce a different hash output.
  3. Collision resistant means no two inputs should create the same output.
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#3602
  1. Hash functions are mathematical functions that convert an input of various lengths and then converts it into a fixed length output that is unique like a fingerprint.
  2. Hash functions in crypto currencies like Bitcoin are used to write new transactions into the blockchain thru the mining process.
  3. When 2 separate inputs produce the same output in hash functions, that’s a collision. So we need it to be collision resistant where no 2 inputs give you the same output giving the result a unique fingerprint of its own.
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#3603
  1. Describe hash functions with your own words
    A hash function is a function where an input produces a special output or fingerprint which cannot be reproduced or reverse engineered.
  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash function are 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?
    it means that 2 inputs will get 2 different outputs
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#3604

  1. Hash functions take two inputs and create a unique output. Finding the inputs from the output is next to impossible.

  2. Hash functions are used to validate the blocks. Each hashed block needs to return a specific output. Miners hash the block and search for the unique key to return the specified output. When the unique key is found it is included with the hashed block and added to the next block to be hashed.

  3. Collision resistant means that outputs need to be unique enough that any two sets of inputs cannot produce the same output.

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#3605

Describe hash functions with your own words
A hash function is any function that can be used to map data of arbitrary size to fixed-size values.

How are hash functions used in cryptocurrencies like bitcoin?
Bitcoin uses a hash function takes a chunk of data as input and shrinks it down into a hash value of 256 bits. It is a one-way mechanism. A reverse function to calculate the initial raw data is not possible.

What does it mean when we say that hash functions need to be collision resistant?
A hash function is collision resistant if it is hard to find two inputs that hash to the same output.

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#3606

  1. A hash function is a device where a input gets its unique output

  2. Hash functions are used in Bitcoin for mining. A miner takes input from a block and creates a hash of a certain length that must match the hash of the block that is being mined. This is a very difficult and energy consuming task.

  3. Collision resistant is a quality where two inputs do not give the same outputs or hash.

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#3607

  1. Describe hash functions with your own words
    Has functions are one way, from input to output to create a digital finger print, it cannot reverse.

  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).
    Has function are use to encrypt the transactions data so it’s secure and only the intended can decrypt it.

  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).
    Same output for 2 or more different input, which is very rare.

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#3608
  1. A hash function is a one-way function that for each unique input then will produce a unique output.
  2. Bitcoins blockchain uses these important hash algorithm characteristics to run its consensus mechanism.
  3. It is hard to find two inputs that hash to the same output.
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#3609

  1. A hash function is a function where an input produces a special output or fingerprint which cannot be reproduced or reverse engineered.

  2. Bitcoins blockchain uses these important hash algorithm characteristics to run its consensus mechanism.

  3. It is hard to find two inputs that hash to the same output.

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#3610

  1. Describe hash functions with your own words

  2. Hash functions take a unique input and create a unique output. You can’t reverse the process.

  3. How are hash functions used in cryptocurrency‘s like Bitcoin?

  4. Hash functions are used for security purposes. It makes cryptocurrency tamper-proof and unable to be altered.

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

  6. It is almost impossible for two different inputs to create the same output

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#3611

  1. Hash functions are a one-way function. For each unique input they generate a unique output, but the output cannot be converted into the input.

  2. Hash functions are used to write new transactions into the blockchain through the mining process.

  3. Collision resistant means, that there are no two inputs that have the same output!

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#3612

You can’t reverse a hash output. Its not the same as PK cryptography that has a keypair that is used to encrypt/decrypt data.
Hash functions are used as a fingerprint of the data. A transaction in Bitcoin is hashed so that the hash can be then used as a transaction id (txid). :slight_smile:

#3613

  1. A hash function takes an input value and apply formulae to the input to return an entire different value of a fixed length. This new value can not be reversed to find the original data, thus hashing can be used to verify or compare data to original data.

  2. Miners hash bitcoin transactions called blocks before it is added to the blockchain. This ensures that the blockchain is secure.

  3. It means that it is very difficult if not impossible to find two inputs with the same hash value produced by a hash function.

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#3614
  1. A hash function is a special function that creates a unique output for each unique input.
    In hash functions, You can go from input to output, but never the other way around.
  2. In Bitcoin hash functions are used to encrypt the input data(transactions) and give it a hash fingerprint.
  3. Collision resistance in hash functions mean that 2 inputs cannot hash to the same output.
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#3615

1-Hash functions are algorithms with a unique input that lead to a unique output. These functions can not be reverse engineered per say in which makes them very secure.

2-Hash functions are used to mine bitcoins, but mine them in a way that their total supply is minted over an extended period of time.

3- 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 ≠ b but H ( a ) = H ( b)

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#3616

  1. A hash function is a mathematical process that takes input data of any size, performs an operation on it, and returns output data of a fixed size.

  2. Cryptocurrencies like bitcoin, the transactions are taken as an input and run through a hashing function which gives an output of a fixed length

  1. Collision resistant in this instence means that it is highly unlikely (but not mathematically imposible) to get the same output from a hash function
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#3617

It’s a coded way to transform data into an unreadable mess for humans.

Bitcoin use SHA-256 algorithm only for transactions. Ethereum use KECCAK-256 (SHA-3)

It needs an unique output, you can’t have 2 outputs with the same hash.

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