Homework on Hash Functions - Questions

Blockchain and Bitcoin 101
#1145

Homework on Hash Function.

Describe hash function with your own words.

  1. To simply put a Hash is always a one way function. This means each unique input will give you a unique output. You will not be able to find out the input of the hash function through the output.

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).

  1. In bitcoin hash function is used through mining, transactions and also private and public keys. This property is crucial in bitcoin mining. To successfully solve a block, miners try to combine all of the inputs with their own in such a way that the resulting hash starts with a certain number of zeroes.

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)

  1. In Hash Function a collision resistant means that it very difficult to find two different input that would result to having the same output in a hash Function.
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#1146

1.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.
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 refers to hash rate of the functions . the difficulty is high to find two inputs hashing for the same output.

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#1147

1.they take an input and encrypt it into a totally random output. Same input will always give same output though. Virtually impossible to derive an input from an output with SHA256

  1. Used in mining for proof of work. Nonce is concatenated with hash of block contents and then hashed again and the result has to be less than the current difficulty string. Public keys are also used to verify values that were hashed by a private key (i.e. value was not tampered with maliciously)

  2. It means that the chances of a 2 hashed results being exactly the same are really really really low.

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#1148

Hash functions are unique digital imprints that are created from an input to output. This is a one way system meaning you cant go from output to input.

Transactions that are generated are taken as inputs for Bitcoin and hashed through hashing algorithm SHA-256 to give a fixed output of length. This newly hashed output is taken as input for next block. If data is altered in past blocks this will change subsequent blocks.

This mean that the hash function must be capable of entering the same data n number of times and resulting in same output. and also preventing two different data from generating same output.

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#1149

  1. A hash function helps to process a unique data input into a digitally encrypted output which acts as its unique, irreversible fingerprint.

  2. Hash functions are used in bitcoin mining as proof of work for network nodes verifying new transactions. It includes the blockchain’s full data set as well as other key info such as the time and date of the transaction.

  3. Collision-resistance means that each data input has its own unique output, or that it is at least very unlikely for 2 inputs to share the same output from hash function.

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#1150

Describe hash functions with your own words

  • Hash functions are like a lock & key. The key (input) can be used to unlock the lock (create the output), but the lock can not be used to find the key, at least in my example. (Maybe…?)

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).

  • They are used to prove blocks are legitimate & to show that the senders do in fact have the funds to cover the transaction.

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).

  • Each input has it’s own unique hash, & changing anything would cause the block to be rejected.
#1151
  1. Hash function is a one-way function which generates for an input one specific output. Even a small alteration of the previous input would cause a completely different output
  2. The hash function used in cryptocurrency like btc is a tool of validation in PoW that there has been no manipulation
  3. As long as the hash is preimage resistant it is hard to find collisions which means two different inputs can’t cause the same output
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#1152

  1. One way function, each unique input equating in an irreversible unique output.

  2. Secure hash(s) contain transaction data in secure manageable format

  3. Ensuring that two unique inputs cannot equal the same unique output. Anti-counterfeiting

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#1153

  1. A hash function can take input and generate a “fingerprint” of that input. You cannot take the outputted result (fingerprint) and determine the input from it if using SHA256. It is known that MD5 has been “hacked” and input can now be determined, so we should not use that hashing method.

  2. Hash functions can be used to generate unique fingerprints for signatures, wallet ids, and other unique identifiers within the blockchain.

  3. Input into a hash function should create a unique base16 or base64 hash string. Two different inputs should NEVER create the same hash string. The most minor change to an input would create a very different hash string.

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#1154

  1. A type of function where you input information and receive a unique output. The process is not reversible.

  2. Hash functions are used to encode information for bitcoin transactions so that they are secure and trustworthy.

  3. To be collision resistant, every input must have an output that belongs only to that very specific input and no other.

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#1155

  1. Hash functions are a formula that when given a specific input will produce an output of a specific length.

  2. In cryptographies like bitcoin, its hash functions are used as a way to convey information using a highly secure process.

  3. When we say that hash functions have to be collision resistant, we mean that when there are two different inputs, each one will have its own unique hash and produce a unique fingerprint.

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#1156

It is a function which is used to decrypt any data to one string of a fixed length.

Hash functions are used in bitcoin to combine the block no. With nonce and with text and with the previous hash of the previous block to generate a new hash.

It means that it is very difficult to have two different inputs having the same hash.

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#1157

  1. Describe hash functions with your own words.
    is a hah function that creates an output of data to a specific length not reversible, one way.

  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 compress information and encrypt it securely and verifiably.

  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).

like the birthday paradox when you may have the same output for two different inputs.

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#1158

  1. Describe hash functions with your own words
    For a given input address a unique output address is created.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    The Bitcoin proof of work algorithm is sha-256 (secure hashing algorithm).

  3. What does it mean when we say that hash functions need to be collision resistant?
    They have low probability being attacked successfully. Bitcoin is really hard money. A 51% attack exists but those computer resources are better off put to work mining where real rewards are currently available. In the future bitcoin may have to be upgraded to a more difficult hashing algorithm which could result in needing increased processing power and time to transact. Not a big deal overall…

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#1159

  1. Hash functions can secure data/transactions by generating a unique digital fingerprint based on specific input. For cryptocurrencies, the transactions themselves are the input, but hash functions can also be used as an integrity check for other types of data.

  2. With cryptocurrencies, the transactions are used as the input and run through a hashing algorithm. This produces an output of a fixed length. Rather than having to remember all of the input data (which could be huge), you just remember the hash and keep track.

  3. In a hash function, each input generates a unique output. When a collision occurs, it means two different inputs generated the same output. While no function is 100% collision free due to the fixed length, it needs to be extremely difficult to cause this to be considered collision resistant.

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#1160

  1. Describe hash functions with your own words.
    Hash functions are a one directional fixed size output.

  2. How are hash functions used in cryptocurrencies like bitcoin?
    Hash functions are used in cryptocurrencies like bitcoin as the backbone to the mining process which secures the system through proof-of-work as well as reward the miner with new minted btc.

  3. What does it mean when we say that hash functions need to be collision resistant?
    Collision resistant of a hash functions means that 2 different inputs can not have the same output after going through a hash function.

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#1161

  1. One way functions where an input gives you a unique output like a fingerprint. The output cannot be used to determine the original input or this would invalidate the function aka break bitcoin.

  2. For bitcoin, transactions are taken as the input and run through the SHA-256 hashing algo to give that input a fixed length which can be used to keep track of that input which could be huge.

3.It means that two different inputs should not have the same hash.

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#1162

Homework on Hash Functions - Questions

  1. Describe hash functions with your own words
    Answer: A hash is a way of compressing data. Unlike file comprehsion a hash gives us a code that acts as a short-cut for finding the data. Hash functions combine algorithmic set parameters with AI random generation. For example, in the case of SHA 256 the output will always be 64 (set parameter) characters but the manner in which these 64 characters are generated is through an AI function which generates an output randomly.
    .

  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).
    Answer: In cryptocurrencies hash functions are used both in the generation of coins in a proof of work system as well as in the generation of private and public used for the purpose of a trust less exchange of value. The individuals do not need to trust each other since the math, algorithms and security have supplied that. By including a piece of the hash of the last block and incorporating it into the next block the blockchain creates an immutable 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).
    Answer: Collison resistance means that it is higly unlikely (infeasable but not imporssible) to find two input characters which result in the same output. This is necessary to create unique digital tokens and or assets. It is extremely important in a deflationary asset like Bitcoin since the assets cannot be multiplied the way other digital images can be.

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#1163

1. Describe hash functions with your own words

Hash functions provide a unique output for each input they receive. Hash functions differ from normal functtions in that, given the output of a hash function, it is not possible to determine the original 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).

Each block in Bitcoin’s blockchain is hashed using SHA-256 to provide a unique hash. This allows for the integrity of each block to be verified very quickly and easily, as the smallest change to any portion of a block would result in a completely different hash being generated.

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).

Collision resistance in hash functions is very important, as it makes it infeasible for two different inputs to have the same output. In the case of SHA-256, the “birthday paradox” studied earlier would give a 50% chance to break collision resistance at the sqrt(2^256) = 2^128th instance. This is a number so large that it is infeasible to occur, so the it is safe to assume that if two hash function outputs are identical, then the inputs are also identical.

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#1164

Describe hash functions with your own words
With a hash function you can give a unique digital fingerprint to some kind of digital information.
You can use that fingerprint to verify that information later or to confirm that the transaction really happened for example.
You can never find out what the input was if you only have acces to the output.

How are hash functions used in cryptocurrencies like bitcoin?
A new block contains multiple transactions that are combined in one hash. When that block gets mined, the hash of that block is added to all the transactions in the next block and gets hashed all together. That links the blockchain together in a secure and immutable way.

What does it mean when we say that hash functions need to be collision resistant?
There is a chance that at one point two different inputs produce the same hash (fingerprint). The lower the chance of that happening the more collision resistant the hash function is.
If there a too many collisions, your fingerprint is not guaranteed unique anymore and security drops.

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