Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#4139

  1. Each input a hash function receives will produce it’s own unique output. Hash functions are also a one way function, thus the input cannot be obtained from it’s respective output.

  2. The input of a blockchain hash, called a block, consists of unconfirmed transactions in addition to information from the previous block. In order for a block to added to the blockchain, a mining node must find a hash below the number set by the block’s header.

  3. For a hash function to be collision resistant means that it is impossible for two inputs to produce the same output.

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#4140

  1. A hash function is an algorithm that can process any data into a unique digital “fingerprint” through an input-to-output ONLY basis and cannot be reversed.

  2. Hash functions process the transactions made on Bitcoin and make them secure since the output cannot be reversed.

  3. Hash functions need to be collision resistant because every hash input needs to be unique. Collision resistant means that a hash function’s input does not produce the same output.

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#4141

  1. Describe hash functions with your own words
    Hash functions are functions where it´s impossible to find out through the output, what the input was.

  2. 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.

  3. What does it mean when we say that hash functions need to be collision resistant?
    A hash function is collision resistant, if it´s hard to find two inputs, that hash to the same output.

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#4142

Q: Describe hash functions with your own words

A: A function in which each unique input gives a unique output. You can get from input to output, but not from output to input, so it has a one-way function.

Q: 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: Hash functions are a part of the block hashing algorithm. Block hashing algorithm is used to write transactions in the blockchain by using the process of mining. For a block to solve a hash, with all the bitcoin computer’s network, it takes a lot of computation energy and can be solved in nearly 10 minutes.

Q: 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).

A: We say for a hash function that is collision resistance, when it is difficult to find 2 hash input to result into the same output.

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#4143

  1. Describe hash functions with your own words
    the hash function is a conversion that takes any data and converts it to 256bits and has one way.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    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. What does it mean when we say that hash functions need to be collision resistant?
    that means a hash function is collision resistant if it is hard to find two inputs that hash to the same output

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#4144
  1. one-way conversion of data
  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. collision-resistant = hard to find two inputs that hash to the same output.
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#4145

  1. a hash function is a one way algorithm that takes any string of data (input) and computes it into encrypted data (output) giving it a unique digital fingerprint.

  2. bitcoin uses hash functions as universal translator for computers-cryptimi. inputting data that cannot be altered enables block mining that regulates itself, miners are rewarded by solving equations. because it is based on mathematical equations and data can be encrypted, each new transaction is linked onto the previous block and requires verification on the network, it enables cryptocurrencies to send/convert payments without a third party involved, faster and cheaper than before.

  3. hash functions need to be collision resistant to keep it workable, you cannot have two different inputs with the same hashed output. given two inputs x and y it is infeasible that h(x) =h(y) each one is unique

(feel a bit out of depth now! like i took a leap too far with my own research, can you hold my hand again)

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#4146
  1. A hash function converts any string of data into 256 bits. It is impossible to reverse and therefor privides a unique data identifier.
  2. Hash function is used to hash transaction data.
  3. There can not be two data with the same hash.
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#4147

1- A hash function produces a unique alphanumerical number to each input you feed it with. It is not possible to reverse calculate that number back to the input. The same input will always produce the same output.

2- In Bitccoin miners take the hash of the previous block, plus transactions they want to put into the block they are currenty working on, plus a nonce to create a new hash, that has to meet or be below a set target in order to create a new block.
Also the public key is a hash, generated with the private key as input.

3- Colllision resistance means not to get the same output from to different inputs. every output should be unique to a specific input

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#4148

  1. Describe hash functions with your own words
    A hash function is a one-way algorithm that converts each unique input to a unique output, which is 256 bit.

  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 cryptographic hash function is used for security purposes and constitutes crypto security.
The hash of a transaction makes it easy to identify transactions on the blockchain.

  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).
    When it’s hard to find 2 inputs that hash the same output.
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#4149

  1. A hash function is a mathematical algorithm that converts an input of letters and numbers into an encrypted output of a fixed length. It has 2 special characteristics in that a) each unique input always produces a unique output (digital fingerprint) and b) it follows a fixed path of input to output and never the other way around.

  2. Hash functions are used to write new transactions into the blockchain via the mining process, and perhaps the most common usage of hash functions is in the storage of passwords.

  3. In cryptography, if it is hard to find inputs that hash to the same output, the hash function is collision resistant. Collision resistant may be categorised into 2: weak - bound by particular input and strong - applies to any 2 arbitrary inputs.

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#4150
  1. Hash function is a cryptographic system where allocating an input gives you a unique output, in sha256 theres no way to reverse from output to input.
  2. Hash functions are used for mining, every transaction is hashed so the miners pick up these hashed algorithms and then combine them to create a new block, changing the amount of 0 in the hash nonce they change the dificulty acording to the time needed.
  3. Collision resistant is used to describe the posibilitys there is for two inputs to hash the same outputs
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#4151
  1. Mathematic algorithm for converting input data of any size to a data of a fixed lenght. Output is the fingerprint or hash. HF are used for faster table searching, data comparison, store passwords, etc.
  2. Hush functions in bitcoin protocol are part of the block hashing algorith, which is used to write transactions into the blockchain through the mining process. Inputs are not-yet confirmed transactions.
  3. It is hard to find two inputs that hash to the same output.
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#4152
  1. A hash function is a function that results in a cryptographic digital result that changes completely whenever the slightest change is made to the original input.
  2. Hash functions are used in cryptocurrencies likes Bitcoin to hash the transaction data before being encrypted and added to the blockchain.
  3. Collision resistant means that the probability of two outputs being the same is nearly impossible.
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#4153

  1. Hash functions are very special for 2 reasoasons :

    • for each unique input will produce a unique output;
    • you can go from input to output, but you can never go from output to 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. It is infeasible for 2 different inputs to have the same hash value

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#4154
  1. A hash function gives an unique output of a fixed length for a given input. The input can’t be found be “back feeding” the output.
  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. A hash function is collision-resistant if it is hard to find two inputs that hash to the same output.
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#4155

  1. Describe hash functions with your own words.
    It’s a one way function where every unique input gives an unique output. So you are getting a fingerprint for each input. And it’s not possible to find out what the input was through the output.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions are used so that it would only be possible to add irreversible, immutable data to the blockchain. It also creates the need for a large amount of processing power and bitcoins are mined over long periods of time.

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

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#4156

  1. It is a function where the data that you input is completely transformed to a unique output.

  2. It is use to get a reference number to a block header, transaction and secure the data. In the case of mining to receive a reward by creating a valid block hash.

  3. It is the difficulty for a hash function to create the same output for different input, so that the program won’t be confuse by the similarity and that the hash will be more secure to use.

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#4157

-Each input gives a unique output digital fingerprint that provides one way transaction to only input to output.

-Using in Bitcoin and other crypto currency’s transactions in blockchain data. It keeps the data transactions secure.

-Collision resistance means almost impossible to find two inputs to give same output in a hash function.

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#4158

  1. A hash function yields an output for an input, in a process which cannot be reversed - the input cannot be derived from the output.

  2. Hash functions are used in bitcoins proof of work consensus mechanism, whereby miners must find a hash which starts which starts with a given number of zeroes. The input is arbitrary and the mining difficulty is adjusted by variating the number zeroes with which the hash must start. The difficulty is adjusted such to adapt to variations in the computational power which miners are collectively dedicating to mining.

  3. Collision resistance means that no two inputs will result in the same output. Strictly speaking, the SHA-256 is not collision resistant, but a is so astronomically unlikely that for all intents and purposes, it doesn’t matter.

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