- Describe hash functions with your own words
a Hash function is a cryptographic function that creates a unique output for a given input. That output may not be reversed to reveal the original input unless authorised.
- 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).
The hash function is used in bitcoin to codify the inputs of the transactions that comprise each block on the blockchain which in turn become an integral part of subsequent blocks. Because each hash is unique to the relevant input a change in data will in turn result in a different hash output which will in turn travel up through the subsequent blocks making them null and void.
- 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 Resistant Hash is where the probability of a hash function outputting the same hash for two different inputs is extremely unlikely.