Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#4259

  1. Hash functions are functions that give unique output to a given input, whereas the reverse is not true.

  2. Any transaction’s made in blockchain are encrypted by SHA256, the inputs are orders or confirmed transactions that nodes solve.

  3. Collision resistant means it is hard to find two inputs that hash to the same output

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#4260

  1. Hash function are complex functions, which generate unique output from given input, but there is no way to come from output to input of this function.

  2. In Bitcoin hash functions are part of the block hashing algorithm, which is used to write new transactions into the blockchain through mining process.

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

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#4261

  1. Describe hash functions with your own words?
    Hash functions generate unique output from an input. The function is one-way. There is no way to go from that unique output back to input, making it a secure transaction.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions are used in mining, proof of work, to write transactions onto the blockchain

  3. What does it mean when we say that hash functions need to be collision resistant?
    Difficult to find two inputs that hash to the same output.

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#4262

  1. A hash function is a function that is designed to take an input and produce a unique output that will produce the same output every time.

  2. Hash functions are used in cryptocurrencies like bitcoin to hash the transaction data. This is partly to provide privacy in transactions but also to assure accuracy in data.

  3. Collision resistance is a term that implies a property of cryptography. This is the property where 2 different inputs cannot produce the same output. (although not impossible)

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#4263

Describe hash functions with your own words:

  • Every information entering the network (input) - will be coded in a unique code (Output).This code is made of numbers and letters.It is like a fingerprint.

How are hash functions used in cryptocurrencies like bitcoin?

  • Raw data (example transaction) access the Blockchain ( input ) and through the process of mining . The data is validated and transformed into a unique code (Output) and saved on the blockchain network

What does it mean when we say that hash functions need to be collision resistant?
-That means, they are unbrockable and can praktically not be cracked, duplicated or modified.

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#4264

  1. Hash functions are a part of cryptography that does one way unique inputs that produce a unique output.

  2. Hash functions are used in bitcoin for things like creating public and private keys and signing or authentication of transactions.

  3. Collision resistant refers to a hash function where it’s difficult to find two inputs that are hashed to the same output.

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#4265

1.) Hash functions are one way functions where each input gives a unique output.
2.) Hash functions are used to complete cryptocurrency transactions. The input of the function is the not yet confirmed transaction, as well as a timestamp and a reference to the previous block.
3.) Collision resistance refers to the fact that 2 inputs cannot result in the same output.

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#4266

  1. Hash functions produce a unique digital fingerprint through inputting a linear set of data and then receiving a unique hash function as an output, that cannot be reverse engineered.

  2. Hash functions are used in crypto to write new transactions to the blockchain through the mining process. They also generate a unique address to send or receive crypto and makes it easy to identify and verify transactions on the blockchain. It can also be used as storage for passwords.

  3. Collision Resistance in hashing means that it is impossible for two different INPUTS to produce the same OUTPUT. It doesn’t mean that resistance doesn’t exist, only that the collisions are very hard to find.

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#4267

  1. Hash functions are complex mathematical algorithms that take input data and give a different and unique output fingerprint. You can not get the input by tracing back the output.

  2. Hash functions are used to write or validate new transactions into the blockchain via mining.

  3. Collision resistant means that the blockchain cannot be compromised by having the same input produce the same output. This means that if you would be able to alter previous blocks without it affecting the current blocks meaning someone would be left with a lot more bitcoin in their wallet without paying for it and with no one noticing.

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#4268

  1. Hash functions are a cryptographic operation the generate a unique output directly corellated to a unique input through a algorithm that specificies the parameters of the function.

  2. Through the SHA-256 algorithm, the input of the operation gives a fixed length output and thus creates a block. That block is hashed with the old block, meaning that any attempt to reverse or modify the transaction that created that block will change the block itself and basically break the chain.

  3. Collision resistance translates to the highly improbability (2^256 to be more exact) that two functions, i.e. inputs, will have the same output.

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#4269

1.Hash function translates certain data to the computers,it is impossible to do the opposite.

  1. 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.Collision resistant means that finding 2 inputs that result in the same output is extremely difficult therefore the hash function is cryptographically secure.

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#4270

Hash functions are functions that are based off the input and output method. When you input characters, the output will be between 256 characters ranging from letters, numbers and symbols.

Like Bitcoin, hashes are ran by miners who try to be the first to add a new block to the chain.

Collision resistant mean it’s impossible to have the same outcome with 2 different hashes.

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#4271
  1. Describe hash functions with your own words

Hash functions are functions that return a unique output (fingerprint), from their input. They take binary code information(0 and 1), and convert it into alphanumeric information(letters and numbers).

  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).

They are used in cryptos like btc to produce blocks of encrypted data. Through a mechanism called proof-of-work(PoW), miners work with powerful computers to solved increasingly difficult mathematical problems. When solved they confirm these transactions, and new new blocks (hashes), are created and added to the blockchain. As a result they are rewarded with new bitcoins.

  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).

It means that it must be hard for hash functions to find to inputs that hash to the same output (digest).

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#4272

  1. Hash functions have two key characteristics. The first is that each unique input produces a unique output. Secondly you can go from input to output but not the other way, meaning its a one way function.

  2. In 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. In cryptography collision resistance is a property of crypto hash functions: a hash function is collision-resistant if it is hard to find two inputs that hash to the same output.

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#4273

  1. Hash functions output a unique fingerprint to an input.

  2. Hash functions are used to verify that a Block is original.

  3. It means that every input needs to provide a unique output. In some hash algrithms it is possible to get the same hash (output) from two different inputs.

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#4274

  1. Hash functions are functions which work only in one direction. Here you can get the output from the input but you’ll never get the input from the output. Its unlike normal functions where you can find the input when you know the output. When you create a hash via SHA256 the input will be converted to ones and zeros. Afterwards it will be converted into the SHA256 hash. The numbers 10,11,12,13,14,15,16 will be displayed as a, b, c, d, e, f respectively .

  2. Hash functions are part of the block hashing algorithm which the miner use to save new transactions on the blockchain. Through the hashing algorithm miners are creating new blocks.

3.A hash function is collision resistant when its hard to find two inputs with the same output. If a hash function is not collision resistant, it is insecure.

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#4275

  1. Its a function in which the uploaded data (input) is transformed into a specific and unique fingerprint (output) from which it is “impossible” to get the input

  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. That it must be really difficult to find 2 inputs that hash the same output
    any hash function with more inputs than outputs will necessarily have such collisions the harder they are to find, the more cryptographically secure the hash function is.

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#4276

  1. In a hash function a unique input will produce a unique out put. A hash function is a one way function meaning you can put an input in and get an output however inputting the reverse will never produce the input.

  2. hash functions are used in bitcoin to keep the blockchain secure. Miners will mine for a new block, the new block will consist of a certain type of hash. Once found that block is then added to the chain and the miner is rewarded w some coins.

  3. So there are times on blockchains where two miners will find a block that meet the requirements of their hashing algorithm this “collision” will then cause a fork in the chain. So the more resistant the blockchain is to collision the less likely this scenario will happen.

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#4277

Describe hash functions with your own words
It’s a function that for every unique input always gives the same unique output and it’s a one-way function, you can derive a unique output from the input, but you cannot reverse it, you cannot get the input from the output.

How are hash functions used in cryptocurrencies like bitcoin?
They are used in mining. Miners use the hash algorithm SHA 256 to hash the block header until they get an output that is equal or lower than a given Target.

What does it mean when we say that hash functions need to be collision resistant?
It means that it is hard to get the same output from hashing two different inputs.

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#4278

This is called a stale block and has nothing to do with hash collisions. A collision occurs when two inputs result in the same output. :slight_smile: