Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#3618

1.if you insert unique input you get unique output.It’s one way function.
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. A hash function is collision resistant if it’s hard to find two inputs that hash to the same output

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#3619

  1. Hash functions are complex mathematical functions that assign each input a unique output. They are unidirectional functions, meaning the intput-output operation cannot be reversed.

  2. Hash functions are part of the block hashing algorithm which is used to write new transactions into the blockchain as part of the (Bitcoin) mining process.

  3. Collision resistance means that it needs to be infeasible for the function to have two separate inputs produce the same output.

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#3620
  1. Hash algorithms are special functions because:
  • one input can lead to a single output
  • it’s virtually impossible to get to the original input just by having the output (if possible, BTC breaks)
  1. Hash functions are used in Bitcoin as a way of allowing anyone to create a unique output (a hash) , but making it close to impossible for others to reconstruct the input that was given originally for it. The SHA-256 hash function is used in bitcoin to:
  1. Create bitcoin addresses
  2. Mine coins
  1. Collision resistant hash functions means for a single output, it is very hard to find two different inputs
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#3621

  1. Hash functions by using any sort of data input submitting that information to a hash function or algorithm computation which converts it into an output with a fixed alpha-numeric length. The process is generally unidirectional meaning it is not possible to reverse engineer the process from the output back to the original data input. Thus it serves as a reliable form of encryption.

  2. Hash functions are used in cryptocurrencies in order to encrypt the transaction information. The transaction information is entered as an input according specified protocols for the particular cryptocurrency using the hash process. Each crypto has its own hash algorithm. Bitcoin is known to use the NSA invented SHA-256 algorithm. These computations are very exact meaning the least alteration will cause a unique output. The output from the hash computation is stored in a database that is has permissioned public access but one may not reverse the process from output to input because of the magnitude of computational possibilities that be needed to “guess” the input. Thus the information supplied by the original input process remains secure and private.

  3. “Collision Resistance” refers to the extraordinary difficulty that exists in finding two different hash inputs that hash to the same hash output.

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#3622

  1. A mathematical functions which are unidirectional from input to output. Due to the complexity of function you cannot reverse it and figure out exactly what the input operator was (this is different from normal math functions). The other characteristic is each change you make to input would produce a different output (unique fingerprint).

  2. Bitcoin uses SHA-256 which is a secure hash function which are used when a new transaction occurs and a block is added to the chain. This makes it impossible to trace the input operator. This is known as mining process.

3.Cannot have 2 different output from the same input (unique output for an input)

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#3623

  1. Describe hash functions with your own words —- one way, output cannot be reversed, input cannot be deduced or inferred from output. Uses cryptography to condense large data into unique “fingerprint” that can be verified and compared easily but changes given any changes in 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 function expressed in has algorithm to compress block which can then be pointed at to add as the next block in the chain

  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). No two inputs can make the same output so results given inputs never collide into the same result or output

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#3624

  1. Hash functions are where you input data to achieve an unique output in a way it does’t resemble the input.

  2. Bitcoin is a digital ledger of hashes that utilises “proof of work” combined with SHA-256 to obtain mathematical traceability and unbreakability.

  3. Collision Resistant means it is difficult but not impossible to find another input with the same output.

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#3625

  1. Hash function refers to functions that can only be calculated in one way. It is mathematically impossible to find its original input from the output. Every output is unique for each input.

  2. Hash functions are used in cryptocurrencies by using an arbitrary large input/message to create an output hash of fixed length. In Bitcoin its a fixed 256 length. Hash function creates output hash that looks random, hide information of the input and is computationally efficient.

  3. Collision resistant means that every distinct output should never have an identical output. Its not impossible but it would however take an enormous amount of time to find it.

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#3626
  1. Hash function unambiguously transfer data , which is input, to the alphanumerical string or output and it is one-way function, i.e almost impossible to figure out an inverse function.
  2. Hash function algorithm allows creating blockchain itself, i.e connection of true block of data
  3. Collision resistance is a property of a hash function that is computationally infeasible to find two colliding inputs.
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#3627

  1. Hash functions are functions that have two primary qualities. First, no two inputs create the same output. Identical inputs will, however, because the outputs are unique to each individual input. Second, due to the mathematical complexity of hash functions, it is impossible to work backwards and discover what the input was if you only know the output.

  2. Hash functions are algorithms that, when computed, create the hashes that form the blocks in the bitcoin blockchain.

  3. If hash functions are “collision resistant”, it means that the odds of two different inputs equaling the same output are astronomically low.

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#3628

1Its an algorithm that translates data into alphanumeric code after a mathematical calculation. This ways the information it secured because it’s not possible to go from the input to the output.

2 In the Bitcoin protocol, hash functionswrite transactions into the blockchain through the mining process. Bitcoin uses SHA-256 algorithm.

3 That means it has to be resistant to the attack and protect the data. It should be practically impossible to find two inputs that hash to the same output.

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#3629
  1. Describe hash functions with your own words

Hash functions are functions where you have inputs (preimage/keys) of variable length and you get a unique output (digest/hash value) of a fixed length. As soon as you change something in the input, the unique output will be completely different. There’s also no way to see what the original information is that you inserted. Hash functions are one-way functions.

  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 used in cryptocurrencies like bitcoin by making transactions easy to identify by using the hash of the transaction. It is also used for security purposes when writing 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).

A hash function needs to be collision-resistant so that two different inputs (digest/hash value) do not create the same output (digest/hash value). The following should not happen when two inputs a and b where a ≠ b, but H(a) = H(b). If this does then security is compromised.

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#3630
  1. Describe hash functions with your own words.

Hash functions are producing fixed length digit output from random input.This output could be also called a fingerprint.

  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 cryptographically writing new transactions and adding blocks to 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).

Collision-resistant refers to a hash function that is highly unlikely for two different inputs to hash the same output.

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#3631

A hash function, a cryptographic algorithm, is a one-way function which takes a digital input and using SHA-256 generates a unique fixed-length output and is used as a digital fingerprint. The output cannot be reversed to the input.

Hash functions, SHA-256, are used by miners to hash the block header. Generating a hash with 18 or more zeros and less than the target hash the miner can add a block in the block chain.

A hash function where finding any two inputs having the same hash digest is difficult.

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#3632

  1. A hash function takes any data input and creates a new representation of that input as an output

  2. Hashfunctions are used in Bitcoin network by hashing the transactions and the last block, to create a new block, and by checking the hash, it is possible to validate that the last block was not altered.

  3. Collision resistant means that two different data inputs do not produce the same output from a hashing function.

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#3633
  1. Hash function - each unique input gives each unique output. Output is unique digital fingerprint of alphanumerical string as one way function you cannot reverse. For BTC it is SHA256.
  2. Hash function is needed in mining process of BTC. In order to add boudled block on blockchain miner need to find the hash that need to reach the target of difficulty. Block is boundled of several transactions and as well of the information of the previous block.
  3. Collision resistence means if there is hard to find 2 inputs that hash to same output.
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#3634

  1. It is used to create a unique output value from a unique input.

  2. It it used to pass transaction information anonymously.

  3. It is a property of hash functions, when a hash function is collision resistant it is hard to find two inputs that hash to the same output.

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#3635

  1. Hash functions are encrypted functions that cannot be reversed. Thus creating a traceable digital fingerprint.

  2. Hash functions are used in crypto currencies through blockchains and the mining process. The hashing is used to verify the blocks and the transactions.

  3. When we say hash functions need to be collision resistant it means, its needs to be hard to find two inputs that hash to the same output.

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#3636

  1. Describe hash functions with your own words
    It’s transformational tool which transforms texts, numbers etc. into unique digital linear code

  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).
    Not sure exactly but remember these linear codes when sending money from wallet to wallet, so it must be something with recognition and verification

  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 xyz inputs it’s hard to find 2 same outputs, they exist but it’s hard and very unlikely to find

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#3637

  1. A special function where each input produces a different output. It’s a 1-way function meaning you can only go from input to output and not the other way around.

  2. In Bitcoin transactions are hashed using SHA-256 which leads to a unique 256-bit digital footprint. The hashes are used to create the blocks and link them on the blockchain.

  3. This means it’s highly unlikely that 2 different inputs will result in the same output after going through the hash.

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