Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#5321

  1. A hash function is a complex one way function that is unique, equivalent to a finger print. Once an output has been generated there is no way to reverse engineer this process.

  2. Cryptocurrencies such as bitcoin use hash functions to process transaction information anonymously, as well as prevent fraudulent transactions such as double spending and also verifying the authenticity of a file.

  3. Property of a cryptographic hash function is known as “collision resistance”. A hash function is considered collision resistant if it’s difficult to find two inputs that will hash the same output.

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#5322

  1. Describe hash functions with your own words
    hash functions are sha256 encrypted functions which take data and output a 78 digit code with digits
    and letters validating the contents of said data.

  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).
    Each new block contains hash information of the previous blocks on the chain. This keeps the ledger
    trustless, and makes it easy to validate the chain against false hashes.

  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).
    Simple hash functions encrypt data, but are easy to crack. It’s easy for hackers to take the output,
    and trace back the original data. You need to make hash function much more complicated so that no
    2 different inputs can give the same output. Instead you want every piece of data that’s even 1 letter
    different to generate a completely unique hash output.

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#5323

  1. A hash function is a one-way function. Each unique input will produce a unique output that can’t be reversed. Also, by changing the input only slightly, f.e. changing one lower case letter to upper case, will change the output completely. The other property of a hash function is that the output will always be the fixed length no matter how long the input is.

  2. In bitcoin hash functions are used for mining. Through the block hashing algorithm, new transactions are recorded into the blockchain. Also, the hash function is used for creating private and public keys.

  3. It’s one of the needed properties in cryptographic hashing and if a hash function is not collision-resistant, then it’s easier for a bad actor to break the function.

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#5324

Hash Functions are one-way functions which take an input (data) and create an unique output - a unique digital fingerprint. The hash-function creates an output with a fixed-length based on the hashing-algorithm, no matter how long the input is. Additionally, it is not possible to reconstruct the input using the output.

  1. The hash functions are used within the process of mining in order to compress the transactions and the block header into a hash. In addition, the public key is hashed with the use of a hash function - creating a public address.

  2. Collision-resistant means that hash-functions will hash data - and will always come up with a different hash output. Having different inputs but the same hash output is almost impossible.

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#5325

Describe hash functions with your own words

It is a process with input data of any size (a string), making an operation and returning an output (digest) data of a fixed size.

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 essential in security as a while, not only in the bitcoin protocol. They are part of the block hashing algorithm and used through a mining process to write new transaction into the blockchain. In bitcoin mining, the inputs for the function are all of the most recent, not-yet-confirmed transactions.

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 resistance prevents an attacker from creating two distinct documents with the same hash.

a hash function H is collision-resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b where a ≠ b but H(a) = H(b)

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#5326

  1. It takes whatever data you input into it and and then organizes that data into a pre-determined length and unique output.

  2. Bitcoin takes all the transaction data, no matter how large or small and always outputs all the data in 256 character. So instead of remembering all the data, it only needs to remember the 256 characters hash.

  3. It’s 2 different inputs have the same hash. The BTC has to make it improbable to happen

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#5327

1. Is a function used that has 2 main characteristics:

  • each unique input has a unique output (that gives a digital fingerprint)
  • each input gets an output, but you can not figure out the input from the output.

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

  • to make sure nothing has changed (check the authenticity)
  • to save bandwidth - because blocks can be identified by transaction IDs (TXID)
  • to authorize digital signatures

3. What does it mean when we say that hash functions need to be collision-resistant?
Means it’s hard to find two inputs that create the same output

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#5328

  1. Describe hash functions with your own words
    a. A hash function takes a unique input and outputs a unique fingerprint. Hash functions in general are used to keep the integrity of the information being used alongside with a digital signature to the original data.

  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).
    b. Hash functions are used to pass transaction information anonymously

  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).
    c. Collision resistant pertains to having the defense of no two inputs outputting to the same output

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#5329

  1. Hash functions are a one-way function that produces a unique hash value.

  2. Hash functions are used on the bitcoin blockchain as part of the block hashing algorithm. They are also used pass transaction information.

  3. It means that it is very hard to find two inputs that equal the same output. Specifically, in cryptographic hash functions this is an important trait because it ensures that reverse-solving is near impossible.

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#5330

  1. Hash functions take an input of digital text. Turns it into 1’s and 0’s then performs a complex algorithm like SHA 256 to create a unique output.

  2. Hash functions are used in bitcoin to pass on transactional information anonymously.

  3. Functions need to be collision resistant so that the network can stay honest, trustless and immutable due to the nature of cryptocurrency which is performing transactions. two inputs cannot = the same output.

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#5331
  1. Takes a unique random size input and coverts it into a fixed length output
  2. The hash function encrypts the input. The output is impossible to cannot be reversed to find the unique input.
    3.Hard to find 2 inputs that will become the same outputs.
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#5332

Hash Functions-

  1. A mathematical function that has a unique input that gives a unique output. You can’t go from output to input.

  2. Each transaction has a specific output and the miners are trying to find the correct input to receive the rewards for solving that algorithm.

  3. This means that 2 inputs will not equal the same output.

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#5333
  1. A hash function takes an input and translates it into an completely output, that serves as an unique digital fingerprint. You can not reverse the operation - by having the output, you can not discover what the input was. And if you change the smallest thing in the input (a comma or a space, for example), the output would be different.
  2. The hash functions in cryptocurrencies makes it impossible for someone to double spend a bitcoin, for example, or to create a new bitcoin out of nowhere.
  3. It means that two different inputs can not lead to one same output.
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#5334

  1. A has function is an algorithm used to convert an input to a unique output or “digital fingerprint”

  2. Transaction data (address, amount, timestamp) is converted via hashing functions to create transaction ID’s. Previous block hash is added to the next block making the network more secure.

3.Hash functions need to be collision resistant to prevent two hash outputs being the same as two different inputs

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#5335

  1. A Hash function is kind of like a coded representation of data. You change the data, your hash changes too. You cannot find the input from the output.

  2. Hash functions are used in Bitcoin to pass transaction information anonymously, says the internet.

  3. Collision resistant means that it is hard to find 2 inputs that produce the same output, also says the internet. It makes sense, 2 inputs cannot collide. Each output must be unique.

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#5336

  1. Hash functions are one-way functions. You can’t get back to the original data starting from the output.

  2. In Bitcoin hash functions are used as the glue that ultimately protects the mathematical equations that everything is built on.

  3. We can’t find 2 inputs that produce the same output.

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#5337
  1. Describe hash functions with your own words.
  • They are a calcuation that where a unique input ptovides ad unique output, like a digital fingerprint. Also, output can never be used to calculainput, otherwise the hash is broken.
  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).
  • Used in cryptocurrencies to pass transaction information anonymously.
  • Hash functions take in an input of any length, apply a mathematical function on this input and generate a fixed-length output called the hash digest.
  • They were originally designed for Information Security.
  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 for two distinct inputs, the output of the hash function should not be the same.
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#5338

  1. Describe hash functions with your own words -
    Has functions, are complex mathematical, unidirectional functions. The output of a hash function cannot be used to reconstruct the input values. Hash functions are used in cryptography. The inputs to the hash function are the recent, unconfirmed transactions, combined with a timestamp and reference to the previous block.

  2. How are hash functions used in cryptocurrencies like bitcoin? - They are part of the block hashing algorithm in Bitcoin

  3. What does it mean when we say that hash functions need to be collision resistant? -
    Collision resistance refers to the idea that it’s unlikely to have 2 different inputs of a hash function, that return the same output. This can happen but it is rare to find two inputs that hash the same output. Collision resistance is desired and an indicator of how cryptographically secure a hash function is.

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#5339

  1. one way function of converting data ( of any size) to a fixed lined output ( signature )

  2. the primary function is ultimately security , If an output could be reversed engineered to derive the original input it would essentially make bitcoin obsolete ( hackable) and the bitcoin network would not longer be considered secure .Hash function create security .

  3. Collision resistance is a property of cryptographic hash functions: a hash function is collision resistant if it is hard to find two inputs that hash to the same output ; that is, two inputs a and b such that H(a) = H(b). Every hash function with more inputs than outputs will necessarily have collisions.

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#5340

1.Describe hash functions with your own words

Hash functions input data and output data that cannot be reversed or manipulated.

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

Hash functions are used to send transactions from one party to another and store them on a public database for everyone to verify if transaction is legit.

3.What does it mean when we say that hash functions need to be collision resistant?

Collision Resistant means it needs to be hard to find a colliding pair of inputs.

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