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A hash function is a mathematical function that converts an input of variable length into an output of fixed length that cannot be reverted back. For bitcoin this is SHA - 256.
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They are used to pass transactional data anonymously.
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It is practically almost impossible to find two hashes with the same output which makes the hash collision resistant.
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its a system where the input always has a unique output
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hash functions are used by incerting a certain transaction in the hash function and getting a string of numbers to retrieve that transaction
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if there are outputs that are same with a different input than there is a collision which shouldnt be happening. so collision resistant is that the output should never be the same.
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Describe hash functions with your own words
Hash functions has a unique input that delivers a unique output, if you change anything in the input the output changes -
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 is a core concept of Bitcoin mining. In this process, a block of unconfirmed transactions is fed to a hash function and a hash digest is generated. The miner uses this hash digest and adds some input from his/her end to generate an output that contains a certain amount of leading zeroes,
- 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 for two distinct inputs, the output of the hash function should not be the same.
So, mathematically, we can say that for 2 distinct inputs X1 and X2, Hash(X1) should not be equal to Hash(X2)
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- Hash function have unique inputs that gives an output but can never go from output to input
- Hash functions are used in cryptocurrencies like bitcoin because it provides a function that basically āfingerprintsā a piece of data for a given input in turn produces a unique output, that is just a short binary string that identifies this data.
- Pigeonhole principle guarantees that some inputs will hash to the same output. Collision resistance doesnāt mean that no collisions exist; simply that they are hard to find.
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great answer. Thank alot.
1-hash function is a mathematical function that converts any input to a unique output of fixed length (depending of which hash function is used) ex: SHA-256 for BTC
2- In BTC the SHA-256 hash function turns inputs such as the senders address+currency type+time etc and turns it into a unique output hash which is done by the computing power provided by the miners.
3- collision resistance means that you should never technically have similar outputs for two different inputs.
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- You can only go from input to output but not the other way, so its a one way function
- Hash functions are used for public keys, block signatures, transcations.
- you get the same output for more than one input
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- Describe hash functions with your own words
A hash function transforms text or binary data (the INPUT) into an unique, fixed-length, hexadecimal string (the OUTPUT).
Some of itās main properties are:
- the same input message will always result in the same output (same hash value) [Deterministic],
- the input can not be generated from the output [Irreversible], and
- it should be impossible to find two different inputs with the same output [No collisions]
- How are hash functions used in cryptocurrencies like bitcoin?
Although hash functions were not originally designed for cryptocurrencies, they are used in some popular ones mainly because of their properties (some of them were mentioned above) that ensure secure transactions over the blockchain.
The hash functions are primarily used for:
- generating public keys, and
- block hashing (core concept of Bitcoin mining)
- What does it mean when we say that hash functions need to be collision resistant?
A collision means the same output (hash value) for 2 different inputs. Collision resistance doesnāt mean that no collisions exist; simply that they are hard to find. If hash functions are not collision resistant, an attacker could much more easily break the function.
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A hash function produces the digital fingerprint of the input. The input can be any sort of (digital) information. Only the exact same input can give the same output. If the input has only the slightest change, the output will be completely different. The has function is a one-way-function which means that it is not posible to define the input based on its output.
Hash functions are used to mine bitcoins. The output has to be below a certain number. Mining means to find the (exact) input that gives the output required.
- If a hash function has to be collision resistant, it has to be very difficult to get 2 identical inputs.
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Hash functions are oneway input to output. They are functions that produce a unique output that cannot be solved in reverse.
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Hash fuctions in crypto currencies are use in PoW mining. Inputs are unconfirmed transactions plus date, time, amount, etc. that have unique outputs. Miners have to take this info and compute by starting with 0ās as the unknown.
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Collision resistant is making it less possible to have two inputs produce identical outputs.
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- Hash functions are a cryptographic algorithm which takes data off any size and creates a fixed bit size. Each unique input creates a unique output. Can only be solved input to output not output to input.
- Hash functions are used to write new transactions into the blockchain. Bitcoin used SHA-256. It takes the input of any length and converts it into 256 bytes.
3.Two different inputs should not equal the same output.
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- Describe hash functions with your own words
its a function that transforms the bits of an expression input in a computer and converts it in a hexadecimal value of 64 bytes
- 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).
So far I have understand , hash functions work as validators of transactions, when one currency changes hands, just like in accounting, a credit and a debit are recorded. This interaction is recorded in a hash function.
- 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 needs to determine the ability of a function that given two equal inputs provides low chance for the same function hash result
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A hash function is a function that provides a unique output for each input. The output is in the format 256 bits. It is impossible to revert (i.e. you canāt determine he input based on the output).
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Hash functions are used in the block hashing algorithm which is used in order to write new transactions on the blockchain. Because of the singular flow, it makes the transactions non reversible, creating security.
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Collision resistant means computationally infeasible. It is deemed impossible to find an input that would lead to the same output.
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^Answers to the questions in the quoted comment.
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!.- Hash functions are mathematical computation processes that transforms any given data into an alphanumerical code of x characters that cannot be converted back into the input data.
2.- Hash functions are used in cryptocurrencies like Bitcoin to encode a whole block when it is mined, then, that hash code is included at the beggining of the next block, building a chain where you can verify the information inside a block with the hash code included at the beggining of the next block. Also, what miners are searching with the mathematical calculations they perform is a hash code.
3.-That it needs to be difficult to find two different sets of data whose hash code are the same.
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Hash functions are designed to produce a random, unique and irreversible output of a set length to use as āfingerprintsā for any input.
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Hash functions are used in bitcoin as an identifier of a block by hashing the rest of the block, including the previous blocksā hash, transaction data and a ānonceā used for mining. The hash has to follow the consensus rules of the network that regulates the difficulty of mining.
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Collision resistance means that it should be impossible to find identical hashes for different inputs. Kind of like how real fingerprints are only useful as identifiers in crime investigations because it is extremely unlikely for two suspects to have identical fingerprints.
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- Describe hash functions with your own words
Hash functions can be go input to output but can not 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).
Hash functions make bitcoin traceable and unbreakable. - 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).
To be collision resistant there cant be two function that have the same hash.
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- Describe hash functions with your own words
- each unique input will provide a new output
- output is a unique digital fingerprint of the input
- unidirectional
- 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).
- miners try to find a hash function and are a form of encoding, they keep bitcoin secure
- signatures
- 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 the encrypted hash should not be able to be decrypted
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Describe hash functions with your own words
Itās a one-way function that produces a unique output for a given input, it works like a fingerprint. Itās not possible to find the input from the output.
How are hash functions used in cryptocurrencies like bitcoin?
Hash functions are part of the block hashing algorithm which is used to write new transactions into the blockchain through the mining process.
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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- A non reversible function that takes an input and returns a string of data of a fixed size. If one bit of data from the input is changed, the hash will be regenerated and look totally different from the previous hash.
- In bitcoin, hash functions are used for mining. To successfully mine a new block you have to calculate what input is required to return the hash target.
- It has to be very hard (almost impossible) to find two inputs that returns the same hash.
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