- The hash function is generating adequately shortened value from (most of the time) a massive trail of information as a result of a mathematical function.
- It is used to create an irreversible output by applying all of the data from the previous block. It is achieved by a complex mathematical equation.
- It must be hard to find two inputs to the hash to the same output. Every hash function must have fewer inputs than outputs.
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- Each unique input produces a unique output.
- When the mining software wants to add a new block to the blockchain, this is the procedure it follows. Whenever a new block arrives, all the contents of the blocks are first hashed. If the hash is lesser than the difficulty target, then it is added to the blockchain and everyone in the community acknowledges the new block.
- If a hash function is not collision-resistant then an adversary can break the function with little effort.
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Hash function is an algorithm that produces an output - a fingerprint of input value in a unique way using SAH 256 in case of Bitcoin
Every time input is the same, the output is the same
It is not possible to deduct the input value if you know the output
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- A hash function is one that takes an input and produces an output of a specific length containing numbers and/or specific letters. This represents a numeric value.
- An example use of hashing within Bitcoin is a block contains (the hash of the previous block | the hash of all the transactions within itself)
- Two different strings should not produce the same hash.
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one way functions where a specific input consistanly yeilds a specific output but not the other way around. You cannot figure out input with the output. This is what keeps blockchain information and transactions secure.
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Hash functions are part of bitcoin algorithm used to record transactions into the blockchain through mining process and to keep platform secure.
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Hash functions need to be unique enough so itās hard to find two inputs that hash to the same output. If not, this makes hash functions susceptible to be compromised.
- Means that, an input is introduced in an algorithm, and give an unique output
- The transactions from the latest bloc and the hash from the previous block, is concatenation together, then is hashed with sha256 algorithm or another and gives an unique output.
- Means that theoretically is possible that can exist 2 different inputs with the same hash, but, the probability of it happening is very low, like in the brute-force attack.
1 - Hash function is a function you take an unique input and gives you an unique out , is one way function.
2 - We take a transaction as input , we put a hashing function as SHA256 and get out an output fixed 256 bit lengeth.
3 - Collision resistance mean is difficult to find 2 different input to get the same output.
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A hash function is a mathematical process that takes an input data (unique set), i.e. numbers, words, etc., of any size, performs a operation/calculation (hashes) and produces an output of the same data (unique set) at a fixed size (e.g. a string of data), like a digital fingerprint.
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Hash functions in bitcoin are used for bitcoin mining. The inputs are the most recent, not yet confirmed transactions (with timestamp and info about the previous block). Hash functions are used to encrypt data to prevent reverse engineering (cannot deduce the input from the output). The theoretical one direction (pre-image resistance), irreversible, feature of hash functions (e.g. input data --> output data) is an important property of proof of work algorithm in mining. This is all necessary to ensure data is intact and/or not altered which provide users the confidence to use the technology.
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Collision in this context is when a hash function produces the same output for two different inputs. If hash functions need to be collision resistant then the operation should prevent the same output for two or more different (or not) inputs (sorry for using reverse logic laziness here~!).
I hope I managed to answer these questions lololol
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Describe hash functions with your own words - special function which gives a unique output and can go only one way from input to output
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How are hash functions used in cryptocurrencies like bitcoin? - used in mining to verify the transaction
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What does it mean when we say that hash functions need to be collision resistant? Given two different inputs A and B where H(A) and H(B) are their respective hashes, it is infeasible for H(A) to be equal to H(B).
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- Describe hash functions with your own words
A hash function is an algorithm where one input results in one unique out and the output can not be traced back to the input.
- 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 preserve privacy and security. (?)
- What does it mean when we say that hash functions need to be collision resistant? (We didnāt use the term ācollision resistantā in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatās how you learn best).
This means that a Hash function can not have two inputs that produce the same output or this could enable double spending of the given crypto. (?)
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1 if you pour ketchup on your mashed potatoes and mix, you can no longer put the ketchup back in the bottle.
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A function that with a given input always generates the same output. Itā easy to go from input to output but almost impossible to go from output to input.
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Public keys are put through a hashing algoritm to create a bitcoin adress, transactions are hashed when put in a block (Merkle root) and entire block is hashed when mining.
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It must be extremely unlikely that two different inputs generates the same output
- Describe hash functions with your own words
Hash functions take some text and create a unique āhashedā code. This is one way and cannot be reversed.
- 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).
Crptocurrencies use hashing by taking the content of a block and creating a hash to add the block. This hash code can be used in a similar way to a checksum to verify the block.
- What does it mean when we say that hash functions need to be collision resistant? (We didnāt use the term ācollision resistantā in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatās how you learn best).
Although hash functions are one way it is possible for two different inputs to generate the same hash code. Collision resistant hash functions stop this.
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Describe hash functions with your own words
Hash function take an input (any length of digital information) & performing complex mathematical operation on it providing alphanumeric string of fixed length.
How are hash functions used in cryptocurrencies like bitcoin?
Bitcoin use hash function to uniquely identify a particular transaction generating alphanumeric output.
Received output is used to create blocks which are link together (mining).
What does it mean when we say that hash functions need to be collision resistant?
Collision resistant means that it is extremely unlikely that two different inputs creates the same output.
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1. Describe hash functions with your own words
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. Hash functions are so-called one-way functions, meaning that one cannot easily deduce the input, based on the output and how the function to create the output operates
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).
a. For POW cryptocurrencies such as Bitcoin, hash functions are used to write new transactions into the blockchain through the process of mining. The use of hash functions generally warrants the immutability of the blockchain.
3. What does it mean when we say that hash functions need to be collision resistant? (We didnāt use the term ācollision resistantā in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatās how you learn best).
a. What it means is, no distinct set of inputs (x, y, z) will - with a very high probability - produce the same output f(x).
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- Hash functions are special functions where every input has a unique output and you can not determine the input from the output, but you will always get the same result for the input using the same hashing function.
- Hash functions are used to ensure cryptocurrencies are immutable, and donāt change and also supports security of the network. Hash function also support the mining process where in order to solve the puzzle and append a new block a nonce has to be correctly concatenated with the hash of the block trying to be appended and that has to be hashed and the result has to be lower than the set difficulty. So in essence hashing functions is the secret sauce that makes bitcoin what it is.
- This means the possibility of having two different unique inputs hashed resulting in the same output is not feasible.
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Describe hash functions with your own words
Hash functions create or output a series of characters (analogous to a fingerprint) from an input. In SHA256, a base 16 alpha/numerical hash is the output. -
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 allow for transactions to be secured and cannot be changed. Going from output to input is almost impossible. It also creates a more efficient network due to the size of output being the same no matter what the input is. -
What does it mean when we say that hash functions need to be collision resistant? (We didnāt use the term ācollision resistantā in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatās how you learn best).
It is difficult to find 2 inputs producing the same hash outputs.
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1**. Describe hash functions with your own words**
Hash functions are a one way unique input that gives a unique output (a digital fingerprint)
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 in cryptocurrencies like bitcoin work using algorithms to produce a fixed length output, for example bitcoin uses SHA-256 to produce a set 256 bit hash/ fixed length output. This is 1 of the 6 properties cryptographic hash functions utilize to be secure ~PRE IMAGE RESISTANCE~ which basically states it is infeasible to determine the unique input from the unique output hash when you utilize a value / algorithm with a high min-entropy, SHA-256 / Keccak-256 (used by Ethereum)
The 6 properties that hash functions have to be secure are:
1.) Deterministic: same result every time (keep track of the input)
2.) Quick Computation: returns hash input quickly
3.) Pre-Image resistance: infeasible to determine the input using the output
4.) A small change in Input changes the Output
5.) Collision Resistant: Infeasible using a Secure Hashing Algorithm (SHA) like 256, that two different inputs will equal the same hash.
6.) Puzzle friendly: H(kIx) = Y high min-entropy: the chosen value is so widely distributed so much so that choosing a random value has a negligible probability of working, the higher the value (number) you choose / assign the higher the min-entropy ~ the wider the distribution.
3. What does it mean when we say that hash functions need to be collision resistant? (We didnāt use the term ācollision resistantā in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatās how you learn best).
It means that input A and input B will not have the same hash (H), it is infeasible for A(H) to = B(H), each input will have its own unique hash. Though it is easier to break Collision Resistance than Pre Image Resistance, it would still take such an incredibly long time (when utilizing a function like SHA-256) that the issue becomes moot.
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Describe hash functions with your own words
A hash function is a function that produces a unique output for based on the initial input
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 in Bitcoin are use to find/mine the next block in the chain
What does it mean when we say that hash functions need to be collision resistant? (We didnāt use the term ācollision resistantā in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatās how you learn best).
This means its statistically improbable that the the same hash is generated by two competing miners
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Hash functions are mathematical expressions that can be used to obtain a āfingerprintā for numbers or text. you can input anything and the output will be a code with a consistent number of characters
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Blockchains use hashing to cryptographically store data on-chain, arranging it sequentially and layered upon previous hashed data making it virtually impossible to alter or see without permission.
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Collision resistance refers to the likelihood of inputting two different values and outputting the same hash value. Hash functions must be collision resistant as hackers can find and exploit vulnerabilities if not.
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