Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#4039

A hash function is a unique input that produces a unique output, it is a one way function. Bitcoin uses hash functions

Hash functions are used in cryptocurrencies like bitcoin by producing a unique private key that only you, the owner has, the private key also creates a public key, and a bitcoin address, needed to verify transactions and acts as a signature

no same inputs = the same outputs! its a one way street on these hash functions, no possible way to go back

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#4040

1: Hash functions are essentially very complex functions that take any given input and produce a unique output. They are essentially impossible to solve backwards which gives security and anonymity to the input of hash functions.
2. They are used by providing an input to the hash function which is comprised of the transaction, time stamp, and previous block data which is always unique. This input will always produce a unique output from SHA 256.
3. It means that no two inputs will produce the same output which is extremely important when dealing with the so many different transactions and numbers and identities in the bitcoin blockchain.

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#4041

  1. A hash function is a mathematical equation that creates a specific digital signature from an input of data. Data from the input is mapped and compressed into a numerical value, referred to as a hash or hash value.

  2. In Bitcoin, hash functions are part of the hashing algorithm which writes new blocks to the blockchain within the bitcoin mining process. Essentially, hash functions are crucial to the proof-of-work algorithm which ā€œsolvesā€ new blocks. This creates security within the system, where transaction data is encrypted.

  3. Hash functions need to be collision resistant, where two different inputs will not have the same output. Technically speaking, it is not possible for two independent inputs to have the same hash value, however, hash values are of a fixed length and therefore could potentially at some point ā€œcollideā€. This would take an astronomical amount of time and computing power to occur. It should be hard to find two distinct messages with the same output (collision resistance).

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#4042

  1. Describe hash functions with your own words

    Itā€™s a function that creates a digital signature of a data input.

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

    As i understand they are used everywhere, for your private keys, transactions, mining, each block, everything gets hashed and creates an irreversible chain.

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

    If hash functions would not be collision resistant (different inputs hashing to the same output) it would defeat the purpose of a hash function and would cause severe problems.

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#4043
  1. Describe hash functions with your own words

A hash function takes some kind of digital input such as text, audio, video, etc, and produces a unique output (a hash) from the input. Itā€™s one-way and from the hash, you can never determine the original data. But given a copy of the original data you can immediately verify it has the same hash.

  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 bitcoin, a wallet doesnā€™t store the plaintext of a password, but rather a hashed version of the password. If the proper password is input, the hashes match and the wallet funds are accessed. If the input doesnā€™t match the stored password hash, itā€™ll say wrong password.

  1. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).

With any hash function, as they are of finite length, there is always a possibility two completely separate inputs result in the same hash value. This is called a collision. Hash functions should ideally always produce a unique output for each unique input, so collision resistance is important.

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#4044

Collision resistance explains the probability of two inputs resulting in the same output. :slight_smile:

#4045

Private key is a random number generated by a computer and the public key is derived using the Elliptic curve function, not SHA256. :slight_smile:

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#4046 
1.	Describe hash functions with your own words

Hash function is a one way function meaning one can only go from input to output, not output to input.ā€™ Furthermore, each unique input gives a unique output (digital finger print)

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 are used a s a part of the block hashing algorithm. This is used to input new transactions into the blockchain via mining

3.	What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).

The need for having collision resistant hash functions would dramatically lessen (but not totally eradicate) the chances of having two unequal inputs reach duplicate outcomes. This is necessary for dramatically lessening the chances of cracking an outcome.

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#4047
  1. Describe hash functions with your own words
  • Every input produces a very specific output. Minor changes to the input with cause a totally different output.
  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).
  • Transactions are written using hash functions and recorded into the blockchain.
  1. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).
  • No 2 inputs must produce the same output.
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#4048
  1. A function that allows each and every unique input to generate a unique output. It is nearly mathematically impossible to work backwards to figure out the input from any given output.
  2. Unique hash value:** For every input, it produces a unique output
    High hashing speed:** For each given input the computation is fast.
    Secure hash function:** It is almost computationally infeasible to reverse the function and make it two-way.
  3. When the number of outcomes of a function is limited i.e. 128 outcomes. Then when you have reached 128+1 outcomes you will have 2 outcomes the same. This is a collision. You can create collision resistance when the size of range and structure of function is robust enough to avoid this.
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#4049

  1. Describe hash functions with your own words
    A hash function is a numerical function. Inputs create unique outputs which serve as digital fingerprints. Change any part of the input and you get a completely different output.

  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).

Bitcoin uses the hash function SHA256. SHA256 creates an output base 64 or 58 which contains a string of unique numbers and letters. If you could turn this input back into its output you would essentially brake bitcoin. This has never been done. Bitcoinā€™s blockchain has therefore proven to be a linear set of outputs and safe use case for digital currency.

  1. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).

A hash function is said to be collision resistant if its hard to find two inputs that hash to the same output.

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#4050
  1. Describe hash functions with your own words

Hash functions are mathematical functions used to encrypt information(numbers, text, files etc) and transform that information into a new form. Doing this has an advantage when you need to see is a file has changed from in a certain period of time. One other example would be when using username and passwords to enter an application. if the application has security it will not store the actual password in the database it will store the hash.

  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.In bitcoin mining, the inputs for the function are all of the most recent, not-yet-confirmed transactions (along with some additional inputs relating to the timestamp and a reference to the previous block).

  1. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™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 )ā€¦

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#4051

  1. Describe hash functions with your own words
    Hash functions allows a unique input to give a unique output, which is a digital fingerpint. This cannot be reversed to determine the input.

  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).
    It is used to add new transactions to the blockchain when mining. The difficulty in getting the correct outcome enables bitcoin to be mined over time, not immediately.

  3. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).
    No two input hashes should give the same output. It prevents hacking, a ā€œfakeā€ input cannot be used to get the legitimate output

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#4052
  1. Describe hash functions with your own words

Hash functions are new algorithm ways to protect data, it cannot be reversed, deleted, or modified. These algorithms are uniques and they only have 1 result which is practically impossible to decipher by the deconstruction of the equation

  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).
  • I think the hash functions are used to re-affirm e each part of the transaction previous to the confirmation. Is really necessary for the Bitcoin/cryptocurrencies because each function is regulated by a referee (computer) which needs to solve it before continuing the route.
    This confirmation usually takes 10 minutes
  1. What does it mean when we say that hash functions need to be collision resistant? (We didnā€™t use the term ā€œcollision resistantā€ in the lecture, but you will easily find this on Google, we add this question intentionally to make you research information on your own, thatā€™s how you learn best).
  • 2 inputs looking for the same output is a collision resistant (which is not possible)
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#4053
  1. A hash function is a function that creates a unique fingerprint to a unique input.
  2. Hash functions are used to write the new transactions onto the blockchain.
  3. To be collision resistant 2 inputs cannot equal the same output
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#4054

  1. A hash function is a digital fingerprint that has a unique output from a given input. It can only go from input to output and cannot be reversed.

  2. Hash functions are used to produce bitcoin because it is like a lottery system when mining bitcoin. The miner has to produce a hash that is equal to or less than a specific number in order for the bitcoin to be mined. The hash function is used to hash transactions with a unique output that cannot be altered on the blockchain.

  3. Collision resistance means that it is extremely difficult to find two inputs that yield the same output.

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#4055

  1. Hash functions are special functions that will always produce a unique output with every different input. Its goal is to be a one way function going from input to output only.

  2. I believe they are used to secure crypto wallet addresses so that they donā€™t get hacked. The key phrases are never to be revealed and can not be deciphered through brute force by looking at the hashes alone (The input can not be found through the output). The hashes are the addresses of wallets in which people can copy and pace to do transactions in which minors are then put to work to verify the transaction using their own data in the blockchain and by solving the very difficult mathematical problem of achieving the the output required to mine the transaction into a block which then gets added to the blockchain.

  3. What it means is that hash functions need to have it so that more than one input donā€™t share the same output. This will help secure the hash function algorithm so that hackers donā€™t try to crack the system by figuring out the input through the output information.

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#4056

1_ Hash functions are translators (or one way enigma machines) that transforms an input data into a unique output data ( string of letters and numbers) that are not reversible.

2_ It is used in cryptocurrencies to reach consensus and to mine blocks

3_ A hash function that makes it improbable that two different inputs do not produce the same output

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#4057

  1. Each unique input will produce a unique output. When you put a number in the hashfonction, the output gonna have a unique digital fingerprint.

  2. The hash fonction is used to start from a private key(input), and from this key it will generate a public adress(output). Every one can know your public adress and deposit fund to your account, but cant find the private key from it that make your wallet safe .

  3. That mean that we cant have 2 input for an output. Soo when i send Btc to a public adress, its cant go too 2 different wallet with 2 different private key(input)

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#4058

1. Describe hash functions in your own words
Hash functions are mathematical processes that produce a unique output for each unique input that is given. A hash function is a one way function that is very complex and pretty much impossible to crack.
2. How are hash functions used in cryptocurrencies like bitcoin?
In cryptocurrencies like bitcoin, hash functions are part of the block hashing algorithm used to verify and 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?
Collision resistance means that itā€™s incredibly difficult to find 2 inputs that produce the same output in a hash function.

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