Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#5061

  1. A hash function is a “one way” function that takes a unique input and produces a unique output.

  2. They provide a secure way for network nodes to verify changes to the blockchain.

  3. No two input hashes should map to the same output hash.

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#5062

  1. A hash function is when a computer translates an input (digits, letters or media files) into a random string of letters and numbers. The out is what is known as the hash (or digest). Each hash produced is unique, and can never be reversed to calculate the initial input.

  2. Hashes are used in the cryptocurrencies like Bitcoin during the mining process. Miners must solve an equation with a known partial input, to create a hash target. Miners need to try and guess the digital input to reach the harsh target, and resolve the problem. The first minor to resolve the equation is the winner, and in Bitcoins case, is rewarded with the newly mined Bitcoin.

  3. In cryptography, collision resistance is a function of hashing which prevents two separate inputs generating the same output.

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#5063

  1. Describe hash functions with your own words
    Hash functions are functions that only work one way, currently they haven’t been cracked but maybe they will in future with stronger quantum computers. With hash function each unique input gives a unique output. You get a text -> bits (SHA-256) -> Binary Hash -> Hexadecimal 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).
    Block hashing algorithms are used to write new transactions into the blockchain through the mining process. In order to solve this complex mathematical challenges, bitcoin miners are required to have a huge computational power in order to solve those challenges and get rewarded for it with financial incentive - bitcoin.

  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).
    Collision resistant means that it’s hard to find two or more inputs that hash to the same output. In a SHA-256, 2^256 there will always be some collision, meaning that two inputs will result in same output(hash), but it’s important that those collisions are hard to avoid collision attacks or at least make them much harder.

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#5064

  1. Describe hash functions with your own words -> a hash function creates a deterministic output from a given input but it is not possible to go backwards to calculate the input from the output. This means that the same input will always lead to the same output but it is a one way street, so to speak…

  2. How are hash functions used in cryptocurrencies like bitcoin? They are used in consensus algorithms for example mining and also in generating public keys from private keys

  3. What does it mean when we say that hash functions need to be collision resistant? -> this is important in crypto currency so that the money stays safe. A collision is the case when an address is calculated from a private key and this address is already in use. The person who found this address can now transfer the funds at this address and basically steal the money by using the private key with which they found this address

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#5065

1. Describe hash functions with your own words

Hash function is a function that produce unique output to unique input, and it’s only one way, meaning you cannot find the input by using the output.

2. How are hash functions used in cryptocurrencies like bitcoin?

every new block is added using the hash of the former block, and also miners getting rewarded when the value of the hashed block header is smaller than the target value.

3. What does it mean when we say that hash functions need to be collision resistant?
it means that we want to avoid cases which we will get same output( hash) to more than one input. It’s important that each unique input will create unique output.

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#5066

  1. Its a one way function that produces an spesific output after you gave it a certain input. You can never recover the input based on the ouput.

  2. Hash functions are used to enable transactions. Mineres produce nonce until they find the right hash to announce them to the network.

  3. Close to impossible that two differnet inputs creat the same output.

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#5067

  1. Describe hash functions with your own words
    Hash functions is a way of process or function of outputting a specific data/output after you gave it a specific data/input.

  2. How are hash functions used in cryptocurrencies like bitcoin? Cryptographic hash functions add security features to typical hash functions, making it more difficult to detect the contents of a message or information about recipients and senders.

  3. What does it mean when we say that hash functions need to be collision resistant? * They are “collision-free.” This means that no two input hashes should map to the same output hash.

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#5068

  1. Hash functions are encrypting devices.

  2. Are they used to compress the huge record of previous transactions?

  3. “This means that no two input hashes should map to the same output hash.”

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#5069

1. Describe hash functions with your own words
A hash function is a function that takes raw input and outputs a unique fingerprint of the input using a specific hashing algorithm (MD5, SHA-256, etc). The hashed output will always be the same if the input is the same, but any change to the input (change 1 pixel on the image, add/remove a character from a string, etc) and the output will be completely different.

2. How are hash functions used in cryptocurrencies like bitcoin?
Hash functions in cryptocurrency are used during each transaction on the blockchain; a few inputs are put together (the original input, the timestamp, and reference to the previous block), miners on the blockchain then attempt to “solve” this hash using SHA-256 to generate a target hash that is less than or equal to a target output of X zeros.

3. What does it mean when we say that hash functions need to be collision resistant?
Collision resistance (at least for hash functions) means that it is infeasible or impossible to find 2 different inputs that produce the exact same hashed output; if a hash function is collision resistant, it means it’s more secure (than a non-collision resistant hash) because you can only have 1 matching hashed output for 1 unique input. Hash functions need to be collision resistant because it greatly increases security which in turn increases trust in the hashing algorithm uses.

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#5070

1.) without the hash function there would not be any blockchain who works with the POW consensus. A hash function has always only one way, you can hash somethind and then you get a unique combination from letters and digit, its impossible to came from the output to the input with SHA256. When you can hack the output from SHA256 then you broke bitcoin.

2.) hashfunctions are used for genarating bitcoin adresses and the bitcoinminers need them to produce the previous block hash parameter.

3.) it means that the hash dont give any things from the input in the output. This can save the thing that there is no input with the same output.

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#5071
  1. A hash function is the result from taking an input, placing it through a hash algorithm, with the end product being an output that is specifically unique. The output cannot be reversed, however any change in the input will result in a completely different output.
  2. Hash functions are used to write new transactions onto the blockchain on cryptocurrencies like bitcoin. The inputs for the functions in bitcoin consist of all the recent transactions, and a few other factors, combined. The inputs try to solve for a hash that meets specific requirements.
  3. Collision resistant means that you should never have two different inputs that have exactly the same hash.
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#5072

Hello all!

  1. Hash functions are algorithms only readable and useable between computers and are such that any alphanumerical text can be used as input and it will result in a hash that represents that text.
  2. Hash functions are used in bitcoin to represent different wallets and keys to those wallets to access, send and receive funds. They are represented publicly on the blockchain.
  3. Hash functions needing to be collision resistant means that each input has a unique hash, having two inputs with the same output causes collision; no hash function is completely collision-free BUT it is so unlikely that it doesn’t matter and is therefore considered collision resistant.
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#5073

  1. Describe hash functions with your own words.
    This function was designed to solve the hash OUTPUT only, so this function is solved in one linear direction (INPUT to OUTPUT).
    If this function is fed with the exact same data INPUT, it will produce the exact same OUPUT (hash). So, if you change even the slightest character, then the hash output will be completely different.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions are a security feature that meets the encrypted demands needed to solve for a blockchain computation. They are used in cryptocurrencies to pass transactions anonymously. They are complex and difficult mathematical functions that transform a given set of data into a bit string of fixed size (aka “hash value”).

  • Bitcoin uses the SHA-256 cryptographic hash function.
  • IOTA, a platform for the Internet of Things, has its own cryptographic hash function, called Curl.
  1. What does it mean when we say that hash functions need to be collision resistant?
    A hash function is collision-resistant when two different INPUTS do not generate the same OUTPUT hash.
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#5074

  1. A hash function changes an input to a different output. That output is like a fingerprint. If the output can be used to recreate the input then the hash function is broken.

  2. Hash functions change an input to an output that hopefully can’t be recreated. So with cryptocurrencies the hash can be stored or used instead of the original input. The original input can be a user or a username, passwords or transactions.

  3. That means that it is really hard to find two or more inputs that create the same output. So if it is easy to find two or more inputs to recreate the same output there is not much of a collision resistance.

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#5075

  1. Hash functions are code designed to generate a unique alphanumeric output from any input

  2. Hash functions are used in cryptocurrencies like Bitcoin for things such as digital signatures, authentication, random number generation, password security, and mining

  3. A great hash function needs to be collision resistant, meaning that it’s impossible (or extremely unlikely) to find any two inputs that will generate the same output

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#5076
  • Hash functions are one way functions where each input produces an output or digital fingerprint.
  • Hash functions in Bitcoins are using in mining for new transactions on the blockchain. The inputs for the hash function are the unconfirmed transactions plus additional data related to time and the previous transaction. To solve the block miners try to combine all of the inputs along with data of their own so the outputs start with a bunch of 0’s. It takes a lot of computing power and guessing
    3.Collision resistance means that is very difficult to find 2 inputs that produce the same output in a hash function. This is an important property in cryptographic hash functions.
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#5077

  • Hash functions produce an unique fixed size fingerprint of data. It should not be possible to reverse the function (i.e. to get the input by using the fingerprint and recalculating it).

  • Hash functions are used to encrypt transaction information.

  • Collision resistance means that the hashing algorithm should avoid the case that 2 different inputs produce the same output.

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#5078
  1. Hash functions unlike regular functions provide a unique output for any input… a unique individual fingerprint that cannot be reversed… it is a one-directional function such that the output cannot be used to produce the input.
  2. Hash functions serve cryptocurrencies in the fact that the characteristic of being a unique digital fingerprint serves to maintain the integrity of a cryptocurrency… each crypto is thus identified by a unique value on the blockchain that cannot be replicated or counterfeited
  3. To be collision resistant means that no two different inputs can ever produce the same exact output.
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#5079

1. Describe hash functions with your own words
A hash function is a mathematical/cryptographic function that accepts an arbitrary-length input and produces a one-way value (the hash) that cannot be back-computed to get the original input.

2. How are hash functions used in cryptocurrencies like bitcoin?
Hash functions are used in cryptocurrencies as signatures for each transaction – to ensure that each transaction is unique.

3. What does it mean when we say that hash functions need to be collision resistant?
Collision resistance for hash functions means that for the conceivable range of possible inputs, the output of the hash function is unique (no, or very minute chance of collisions).

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#5080

  1. Describe hash functions with your own words
    Is a function that the input generate an output in hashing algorithm to be secured.

  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 on bitcoin to secured the translations data through SHA-256

  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).
    A hash function is collision resistant if it is hard to find two inputs that hash to the same output.

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