Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#4460
  1. each unique input creates a unique output
    2.hash of previous mined block is copied in new block and if it somone tried to duplicate it then the entire block becomes invalid.
  2. near impossible to find 2 inputs that create same output.
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#4461

  1. Hash funtions are one-way functions, where each unique input gives a unique output. They are called one-way functions, because you can only go from input to output, but never from output to input.

  2. Hash functions are part of the blockchain hashing algorithm, which is used to write new transactions into the blockchain through the mining process.

  3. It means two different inputs must never hash to the same output

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#4462
  1. Hash functions are computational algorithms that produces a unique result that cannot be traced back.
  2. They are used to mint bitcoin, and to the verification of hashes.
  3. It means that need to be hard to find 2 different inputs that produce the same output
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#4463

1. Describe hash functions with your own words

  • They are one-way functions producing an output of fixed size (256 bits in case of SHA-256)
  • Given an input, the function is consistent. provides the same output every time
  • the output is unique for a set of inputs. Even though it cannot be unique mathematically, itā€™s practically impossible to detect a collision (finding same hash/output for different inputs)

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 works based on ā€˜Proof of Workā€™ algorithm. To prove the work done, miners are required to find a nonce which combined with the block data produces a hash with certain number of zeroes

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 higher the difficulty to find two inputs of the hash function which give the same output, the higher collision resistance the hash function is
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#4464
  1. Describe hash functions with your own words
  • Each unique input gives an unique output (unique digital fingerprint)
  • One-way function whereby you can go from input to output, but you can never derive the input from the 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).

Hash functions are used as part of the block hashing algorithms, which is used to write new transactions into the blockchain. This is done through the mining process.

  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).

It means that it is very difficult to find two inputs that hash to the same output.

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#4465

1 A hash function is a one way function in which every variable input will provide a completely unique output

  1. Hash functions are used to write new bitcoin transactions on the blockchain (mining). The data inputted in the hash can not be altered or erased as its on chain and every hash is unique therefor the only way to mint new coins is viash the mining.

  2. It means it is extremely unlikely statistically that two different inputs would hash the same input

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#4466

Describe hash functions with your own words

  • Hash function is a procedure where any input is transformed into a totally unique output or a fingerprint and it cannot be reversed.

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 and the inputs for the function are all of the most recent, not-yet-confirmed transactions. It is also use in the creation and generation of the bitcoin address.

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

  • Collision resistance doesnā€™t mean that no collisions exist; simply that they are hard to find. A hash function needs to be collision resistant since we cannot have the same outputs for two inputs.
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#4467
  1. hash functions map any input string to an output (called hash) in such a way that there is no chance to figure out the input that lead to a specific output hash.
  2. hash functions are used in proof-of-work (pow) crypto currencies to generate (hash) a new block. Therefore a hash with a specific amount of zeroes at start needs to be found (amount of zeroes = difficulty)
  3. collision resistant means, that there are no 2 inputs with the same output.
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#4468

1.) Hash functions put unique inputs and gives a unique output and the output can not be reversed to see what that input was

2.) Hash functions are used to write new transactions into the blockchain

3.) Collision resistant is when the hash function is difficult to find two unique inputs that are not the same but has the same output to prevent fake transactions being written into the blockchain

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#4469

Hash functions are one-way functions that map data of arbitrary size to unique number of fixed size.

Hash functions are used in 2 ways. Firstly, by hashing transaction data, crypto make sure that recorded transactions havenā€™t been changed. Secondly, cryptos with proof of work use reparative hashing in the mining process.

Hash functions need to be collision resistant, meaning we donā€™t want different inputs resulting in same hash output. If it was easy for to produce the same hash from different inputs, one could create fake set of data that with a hash value that matches the hash value of a genuine set of data, destroying the security of crypto transactions

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#4470

  1. Hash functions take an input and process it to create a unique digital output (fingerprint). It is a one way process (knowing the output will not let you ā€˜back calculateā€™ to find the original input.

  2. Hash functions in Bitcoin are part of the block hashing algorithm used to write new transactions to the blockchain through the mining process. The algorithm contains transaction information, timestamp information and reference to the previous block, and hashes this information into a unique output.

  3. Collision resistance ensures that it is impossible to produce the same output from two different inputs.

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#4471
  1. Describe hash functions with your own word
    A hash function is a function that take unique input and turns it into unique output that cannot be reversed.

2)How are hash functions used in cryptocurrencies like bitcoin?
Hash Functions are used to build connected blocks that are encrypted and encoded as they progress.

3)What does it mean when we say that hash functions need to be collision resistant?
It means that the Hash function H is collision resistant if it is hard to find two inputs that hash the same output.

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#4472

  1. A Hash function is a mathematical process composed in a string of codes based on the size of the input of the data which result in creating a unique output like a fingerprint.

  2. Cryptocurrencies function like the Bitcoin in creating a hash function. Every transaction is a Ledger attached to the previous ledger block sequence and remain in the order of the output that never changes.

3)Collision resistant is that no 2 hashes have the same output.

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#4473
  1. Hash functions are the one-way functions that you can never find the input from outputs and each unique input, produces a unique output.
  2. Hash functions in Bitcoin are used to confirm the transactions and prevent double-spending by users to prevent fraud and keep the network secure. In fact, they solve function algorithms to be rewarded in BTC.
  3. A hash function is Collision resistant if giving two different inputs have no same output.
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#4474

1 a hash function is a way to create a unique but simple string of data for verification purposes on a larger data pool it also can not be worked in reverse to see what created the hash.
2 exactly as described above. all the transactions plus the previous hash are fed into the function which creates the next block. this creates an extremely secure system.
3 collision resistance no 2 inputs can create the same output.

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#4475
  1. A hash function is a function that can only be solved in a linear, unidirectional way.
  2. A hash function in bitcoin is used to add new transactions into the blockchain through the mining process
  3. Collision resistance refers to the inability to find two inputs to a hash function that gives you the same result
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#4476

so here it goesā€¦

  1. A hash function is a type f algorithm that takes any size input and gives a very specific size output that is a fixed-length character string. now a hash function has to have some pretty distinct properties that give it its security and high level of protection. Some of these properties are that its deterministic, computationally quick, collision resistant, pre-image resistant, unidirectional, efficient, able to meet varying levels of difficulty during mining, and that any change to the input gives a different output.

  2. Hash functions are used in cryptocurrencies on so many levels but really they all center around security and efficiency. Simply put it is used to record all transactions and information in a very secure manner while ensuring its efficiency throughout the blockchain growth. this is what makes it reliable and able to maintain its decentralized state of existence.
    It makes things secure because once the transactions and information are put through the hash algorithm they can be altered due to the unidirectional characteristic where the input can not be discovered with the output and any alteration to any block would have to change every block previous due to the way the chain imprints itself throughout. in this way the hash algorithm keeps all transactions final and the blockchain growing in one direction uninterrupted. with every new block created with this hash algorithm, it contains with it all data of the history of the chain. Security also comes from the fact that it is collision resistant where no two inputs that differ in any way can create the same output and the vast possibilities of a unique output makes it near impossible to find an input with brute force. which would be the only way to crack it since the hash output is pre-image resistant.
    It is through the efficiency of all of this that the hash algorithm can keep the proof-of-work process fairly quick while keeping the blockchain tamper-proof and inalterably secure. This keeps the who-owns-what-and-where reliable.
    3)Well it means that even with thousands of inputs a day within the whole life of blockchain past, present and future to comeā€¦ no two inputs will cause or result in the same output. It means that the result of the hash function will result in a unique out put with even the slightest change to the input. This is a ā€œneed beā€ situation due to the fact that if it were to happen then the integrity of the network would be compromised due to the fact that the chain could be altered without anybody noticing. This would leave the hash algorithm broken and no longer usable.

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#4477

  1. For hash functions, each unique input will produce a unique output. It is a one way function. It is impossible to deduct the initial input from the output received. (sha 256 is BTC, MD5 and sha1 got cracked)

  2. In the abstract, a hash function is a mathematical process that takes input data of any size, performs an operation on it, and returns output data of a fixed size.
    This can be used to take a sequence of letters of any length as input ā€“ what we call a string ā€“ and return a sequence of letters of a fixed length. Whether the input string is a single letter, a word, a sentence, or an entire novel, the output ā€“ called the digest ā€“ will always be the same length.
    Hash functions are part of the block hashing algorithm which is used to write new transactions into the blockchain through the mining process. Itā€™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.

  3. Because hash functions have infinite input length and a predefined output length, there is inevitably going to be the possibility of two different inputs that produce the same output hash. If two separate inputs produce the same hash output, it is called a collision.
    Hash functions are data structures used in computing systems for tasks, such as checking the integrity of messages and authenticating information. They are ā€œcollision-free.ā€ This means that no two input hashes should map to the same output hash.
    Chaining is a technique used for avoiding collisions in hash tables. A hash chain is a method to produce many one-time keys from a single key or password. For non-repudiation a hash function can be applied successively to additional pieces of data in order to record the chronology of dataā€™s existence.
    All hard disks ever produced on Earth canā€™t hold enough 1MB files to get a likelihood of a collision of even 0.01% for SHA-256. SHA-256 is theorized to be quantum-resistant.

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#4478

  1. hash functions are a one way function where the unique input gives a unique output. You can not determine the input from the output

  2. In the bitcoin protocol, hash functions are part of the 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

  3. A collision resistant hash function is when it is hard to find two inputs that hash to the same output.

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#4479

  1. Functions that are able to transform an input into a specific output. But not the other way around.

  2. In simple terms, hashing means taking an input string of any length and giving out an output of a fixed length. In the context of cryptocurrencies like bitcoin , the transactions are taken as input and run through a hashing algorithm ( bitcoin uses SHA-256) which gives an output of a fixed length

  3. Collision resistant means two different things not getting the same hash.

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