Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#4700
  1. Hash functions are strings of numbers and letters which code a specific and unique message.
  2. Hash functions are used in order to hide private keys, you can interact with your public key (for lets say making a transaction) but your private key will be hidden for the outside world. Using SHA-256 it is very difficult for someone (who only knows your public key) to crack your private key.
  3. It means that two different input cannot give the same output.
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#4701

SHA256 is not used in hash functions, though the public key is hashed it was done for the purpose of saving on storage (public key is 65 bytes and hash is 20) but historically only the public key was used as well. Public keys are derived using the Elliptic curve function instead. :slight_smile:

#4702
  1. Hash functions give a unique, unchanging output for each unique input. They are complex and it is not possible to derive the input from the output.
  2. Hash functions are used in the creation of an address and in proof of work mining where unconfirmed transactions are taken as an input and run through a hashing algorithm.
  3. To be collision-resistant means that it is impossible for two different inputs to produce the same output.
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#4703

  1. A hash function is a function where any unique input is converted to a set size output. Any and all inputs, regardless of size, will give a unique output.

  2. Hash functions are used in cryptocurrencies in the mining process where the functions are used in combination with cryptography. Using information found in the block header. This information along with the prior blocks info is hashed until a desired output is achieved.

  3. Being collision resistant means that it is impossible to hash two different values and obtain the same result.

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#4704

1: Hash functions are a mathematical process of taking input data (amount is irrelevant) and changing it into a unique hash output (of fixed size). If the original data is changed in any which way then the hash output will be changed also. This is an excellent process to retain data integrity & security.

2: Hash functions in Bitcoin are part of the Blockchain algorithm that is used to write new transactions into it’s Blockchain through the mining process. Miners must put in huge amount of computing work using their own arbitary piece of input data into solving the hash output for a Bitcoin block.

3: Collision resistant means that it is hard to find two data inputs that hash to the same output. Basically the harder they are to find then the more secure the hash function is. ’
SHA-256 is an excellent example of this as opposed to MD5 which has now been broken & not considered collision resistant anymore.

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#4705
  1. Transform and input to an output…!
  2. Used to create the address chain of the next block and verify its validity.
  3. In cryptography, collision resistance is a property of cryptographic hash functions: a hash function H is collision-resistant if it’s 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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#4706

  1. Any type of input data(text,media,numbers or transactions) mathematically hashed to an output. Any change of the data will change the entire hash output.

  2. Number of transactions input into the BTC hash algorithm by miners to get a desired hash value.

  3. Given two different inputs A and B where F(A) and F(B) are their respective hashes, it is infeasible for F(A) to be equal to F(B). What that means is that for the most part, each input will have its own unique hash

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#4707 
1. Describe hash functions with your own words

goven a binary value as input, returns a value that is considered a fingerprint. A secure hash function is not reversible

  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).
    Already mentioned by Ivan, they are used in POW coins to create a competition between miners.

  2. 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).
    I assume it means that 2 different inputs will produce two different outputs instead of the same output.

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#4708

Homework on Hash Functions - Questions

  1. Describe hash functions with your own words
    Hash function is when an input produces a unique output or fingerprint. It is a one-way function.

  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).

Used to write new transactions into the blockchain through the mining process.

  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’s necessary for two different inputs to NOT have the same output.

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#4709
  1. Hash functions are algorithms that can take any amount of data as an input and encrypt them into a unique alphanumeric code as an output that cannot be reversed to find the original input.
  2. Hash functions are used in the mining process, allowing miners to compete or work together in computing “pools” to solve complex hash algorithms. The one who completes the function correctly first wins the incentive of newly mined bitcoin, or divides the winning amongst the others in that pool.
  3. Collision resistance refers to the extremely low mathematical probability of two unique inputs to equal the same output hash.
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#4710
  1. Hash functions are inputs that convert to outputs in a digital unique fingerprint.
    2.A hashing function is simply a mathematical function that can take any form of data or any size (numbers, alphabets, media files) and produce a fixed-length output for that particular input.
    3.In computer science, a hash collision is a random match in hash values that occurs when a hashing algorithm produces the same hash value for two district pieces of data
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#4711
  1. Hash functions are a one way computation. You can put in an input to get an output but you can never put in the output and get an input. Much like a digital footprint

2.Hash functions are used as a unique transacion. It is used for security purposes. there is no way to crack the code. Hash functions is used to write new transaxtions into the blockchain through the mining process. It’s the backbone of the security. The hash also makes it easy to identify transactions on the blockchain.

3). Collision resistant means that it is computationally infeasibile to find two colliding inputs. You cannot have two inputs that lead to the same output

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#4712

1. Describe hash functions with your own words

The hash function is a special function that accepts any form and size of data including digits, letters, or even large media files, and converts them into an alphanumeric string of a certain size. Standard sizes are 64-bit, 128-bit, and 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).

Hash functions in cryptocurrencies are used for encrypting data like addresses (public and private keys), transaction details, and digital signatures. Then the encrypted data is stored in the public ledger.

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).

Hash functions need to be collision-resistant basically means no two unique inputs should be able to create the same hash as the output.

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#4713

Questions:
. Hash functions are packets of data, where there is a unique output for each given input and it is a one way function where you can only go from input to output.
. They are part of the algorithm which is used to create new transactions through mining.
. Collision resistance is crucial in order to prevent hackers from breaking the code as they would otherwise be able to analyse results and then two different inputs would create the same output.

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#4714

  1. A hash function is a mathematical function that converts a unique input into a unique output. If any of the input elements are altered, an alternative output will be calculated. Hash functions should be linear and compute input to output, but never output to input. It is a unidirectional function.

  2. Hash functions in Bitcoin are part of the block hashing algorithm, which is used to write new transactions into the blockchain through the mining process. Each block header has the hash of the previous block, so, if any of the previous blocks were changed in any way, the output would result in a different hash.

  3. To be collision resistant means that it needs to be difficult to find two inputs that hash the same output. Any hash function with more inputs than outputs will have such collisions. The harder they are to find, the more secure the function is.

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#4715

  1. Hash function: one way function resulting in a unique digital fingerprint. When you hash something you get a digital fingerprint that is in numbers and letters. If anything is changed in the file the hash will be different.

  2. How are hash functions used in bitcoin? they are used to pass transaction information anonymously.

  3. Collision resistant means the chances of you finding two inputs that result in the same output is rare.

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#4716

  1. Input gives an output but you cant go from output to input.

  2. Used to write new transactions into the blockchain.

  3. Hard to find two inputs that hash the same output.

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#4717

  1. Hash functions take an input and it produces an output with a unique digital fingerprint.

  2. Hash functions are used in cryptocurrency mining. The miners attempt to solve complex equations in order to turn that input into an output that creates part of the blockchain.

  3. Collision resistant means that no two similar inputs can creat the same output. If the input is close (even a comma difference) or there is a possible collision, there is no way that the output can be the same.

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#4718

  1. Describe hash functions with your own words
    A good hash function is one way function (cannot be calculated backwards with current technology) where the output for every input is completely unpredictable until has been computed (so you cant narrow down the outputs based on other computed results.)

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Used for proof-of-work mining, first computer verified to create a valid block with a hash under an agreed number adds the block to the chain and gets a reward.
    The transactions themselves use hash functions in the signing process, the block containing the transactions also has a hash, which makes part of the input for the proof-of-work hash.
    Hash functions are also used in generating addresses.

  3. What does it mean when we say that hash functions need to be collision resistant?
    Although there are theoretically infinite inputs that make the same output it is close to impossible unlikely to ever find 2 inputs that make the same output. This property makes the hash a reliable way of identifying arbitrary blocks of information.

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#4719

  1. Describe hash functions with your own words
    Hash functions are almost like digital finger print for data. So if I write “Hello World” and ‘hash it’, it will get a unique hash value according to the hash function I use. These can be used to secure 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).

In cryptocurrencies hashing functions are part of algorithms used to add i.e. bitcoin transactions on block chain. Every transaction on chain is hashed together with the hash of previous block - making it immutable once added on the block chain as if the value in transaction would change, so would the hash.

  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 is very unlikely that there are two similar blocks with same hashes as there are so many permutations of the “finger prints” generated. The number is finite, but still it is so big that it would take years and years. And then some more years.

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