Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#4620

  1. a hash funcion translate a given input (text, numbers…) into an hash-code. Whats special about this funcion is, is that there is no way to reverse the calculation.

  2. In Bitcoin they are used for miniers to find a specific combination for the block and as a digital fingerprint for every unique transaction.

  3. collision resistant means that there cant be the same output for two different inputs and the other ways around.

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#4621
  1. One way functions, getting an unique output due to its given input.
  2. Hash functions are used in crypto to hash transaction data. Mining is done through a hash containing the previous block plus the new one
  3. That two input hashes should not result into the same output
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#4622

Describe hash functions with your own words
Its used for encrypting inputs. It supports data integrity

#4623
  1. Hash functions are one way functions. The input produces an output a.k.a a digital fingerprint
  2. Hash functions secure information
  3. Collision resistant means that it is hard to find two inputs that hash to find the same output.
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#4624
  1. Describe hash functions with your own words?

Hash functions can’t be reversible and is a one way functions for getting a unique output due to it given input.

  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).

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. It’s the need for this large amount of processing power that means new bitcoins get mined over a long period of time, not all at once.

  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).

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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#4625
  1. Hash functions are one way functions that give an unique output or digital print.
  2. Bitcoin uses SHA-256 hash function to generate random numbers in a way that requires a predictable amount of CPU effort. Generating a SHA-256 with a value less than the current target solves a block and wins you some bitcoins.
  3. Functions are collision resistant because 2 different inputs, even with a minimum difference between them, will never give an equal output.
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#4626

  1. Describe hash functions with your own words
    A hashing function is based on a specific algorithm, more or less secure (MD5 or SHA256 for example).
    Those algorithms ensure that it is impossible to find back the input value based on the output value.
    Those functions take input data as argument that can be a file, a string, a number, etc… and produce as a result a unique alphanumeric (letters + numbers) hash.

  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).
    **I think that for each transaction created on the bitcoin blockchain, a hash is created. **
    The owner that receive the coin hashes the previous transaction + its public key.

  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).
    So a hash function that is collision resistant means that the number of outputs is so big (SHA256 for example is 2²256 possibilities) that it makes really hard to find 2 different inputs getting as a result the same hash output (which is a collision).

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#4627

  1. hash functions are similar to a standard function whereby an input is given and it produces output. However, in these functions the input and the output are both unique since when an output is produced it becomes a unique digital fingerprint of the input. Also, hash functions are a one-way system you cannot reverse the process from an output to an input.

  2. Within Bitcoin, a hash function would be part of the block hashing algorithm which is tasked to write new transactions into the blockchain whenever you mine bitcoins. The inputs of the hash function are recognized as most recent and unconfirmed transactions, as well as extra data regarding time and previously made block on the blockchain. To solve the block successfully, miners of Bitcoins need to bring together all inputs plus their own data so that the outputs can begin with a specific number of zeroes.

  3. In simple terms, it can be defined as being very hard (but not mathematically impossible) to locate 2 inputs that can result in an identical output within a hash function. Thus, 2 inputs will most of the time product unidentical outputs.

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#4628

It’s have fiction to only input and than output to be safely and irreversible!

2- it’s used to make mini transfer 64-128-256 with one way system to be safe!

3- it’s hard to do because the algoritmo input will be used for 1 or more outputs.

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#4629

  1. Describe hash functions with your own words
    Hash functions are mathematical functions that convert an input of any length into an encrypted output of a fixed length. The slightest change to the input will produce a different hash but if the original data is entered again, it should produce the original hash.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    The validation process for blockchain transactions relies on data being encrypted using algorithmic hashing, as well as checking the integrity of messages and authenticating information.

  3. What does it mean when we say that hash functions need to be collision resistant?
    This means that no two input hashes should produce the same output hash.

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#4630
  1. Hash functions is part of a computation to produce Hash Value.
    An example of a has function is Sha 256.

Input message+ Hash function= Hash Value

  1. It is used to pass transactions anonymously.
  2. It is a collision resistant because it is hard to hash two inputs in the same output
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#4631

  1. Hash Function is a function that takes in a data which can be numeric, alphabetic, or data such as files etc… and produce a unique fixed size value.

  2. Hash Function is use in Bitcoin to keep track of transaction, each transaction of BTC is being collected to form a block then hashed. This will help keep track cause any tampering with the block will change the hash.

  3. Collision Resistant means two different input cannot have the same hash.

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#4632

  1. Hash functions take a input, a form of data (letters, numbers, words, sentences) and produce an output that is unique to the input, creating a digital finger print.

  2. Hash functions are using in crypto currencies to write new secure transactions into the blockchain, they are also used to generate bitcoin addresses.

  3. Hash functions need to be collision resistant, meaning it’s should not be possible for 2 or more inputs to create the same output.

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#4633

  1. A hash function receives an input and creates a unique calculated output called a unique digital fingerprint. hash functions are one directional from input to output and never in reverse, making it nearly mathematical impossible to decode,

  2. Hash functions are used in crypto like bitcoin to create a unique signature that will be added to the blockchain as all transaction are added.

  3. hash functions need to be collision resistant as the signature is a unique output and the chance of a duplicate is mathematically low.

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#4634

  1. A hash function is a way to give a unique output based on each input in a way that will prevent the original data from being known. It is completely unique for any changes in the input, and so it is a great way to identify transactions with a unique marker or hash. However, it is completely secure and protects the original data.

  2. Hash functions are used by crypto currencies to create a unique digital signature for each transaction while protecting personal data of the person who bought or sold.

  3. Collision resistance refers to 2 unique inputs netting the exact same output. It should be a very difficult thing to occur, however it is not impossible given that the variance in inputs can be greater than the possible outputs

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#4635

*** How are hash functions used in cryptocurrencies like bitcoin?**
Hash functions transform input data via forming a complex mathematical operation on it into fixed-size output data.

*** What does it mean when we say that hash functions need to be collision resistant?**
It’s vital that two different inputs don’t have the same hash output; this is imperative to digital safety. While mathematically this is possible, it’s best if the odds are astronomically long for two different inputs to end up with the same output. In the event two distinct inputs have the same output, it’s referred to as a cryptographic hash collision, making it imperative for a hash to have a strong collision resistance. Otherwise, the algorithm will be vulnerable to collision attacks, which threatens security.

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#4636
  1. A hash function takes data, passes it through a black box, and returns a completely different piece of data. Hash functions are designed to be one-way, non-reversible algorithms. They are commonly used in password storage, data structures called hash tables (dictionaries in some programming languages), and in data integrity verification.
  2. They are used to write new transactions to the blockchain through mining.
  3. That no two different inputs will result in the same output.
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#4637

  1. Hash outputs are unique hash codes that is created by entering an input which generates an unique output, changing one bit will generate a completely new hash code. The input can be any size but gets generated to a fixed size.
    The hash function is the step where the inputs gets generated to an output. It uses the SHA-256 algorithm in BTC to produce the unique output.

  2. A block has it’s sets of transactions which are hashed to an unique hash output, the next block will have the previous blocks hash output plus the new hash output of their own transactions. This process is repeated to all the blocks which forms the blockchain. This makes it impossible for someone to hack since the hashes are based on eachothers, altering one transaction will generate a completely new hashoutput that will not match the other blocks hashvalues anymore.

  3. The Hash function is the algorithm to produce the hash output, by making it collision resistant it means that it is impossible to find two different inputs that generates the same output. BTC uses SHA-256 which means there are 2^256 possible hash outputs that can be generated. The Likelihood of two of the same number gets repeated twice is very unlikely.

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#4638

  1. Hash function is a computation that generates an output ( Hash ). The function can not be reversed . You can not find the input just by knowing the output and the computation used.

  2. Bitcoin uses the SHA-256 hash algorithm to generate verifiably “random” numbers in a way that requires a predictable amount of CPU effort. Generating a SHA-256 hash with a value less than the current target solves a block and wins you some coins.

  3. a hash function H is collision-resistant if it is hard to find two inputs that hash to the same output; means that 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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#4639

Hash function is an algoritme which changed a bunch of data into an alpha-numeric encrypted,non reversable code; an unique fingerprint

Bitcoin uses Hashfunction SHA-256, it’s the proof of work the miners have to do to create a blockchain and recieve their rewards

Because the outcome is a unique alpha-numeric system it is “not” possible to get the same outcome, because the outcome never refers to the income

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