Cryptography Hash Function


While the term itself may seem intimidating, cryptographic hash functions are relatively easy to understand.

We won’t get into too much detail but it’s an important topic as it is the way the blocks are “digitally” attached together, how transactions are "sorted" and how the private and public keys work. 

Such a function is a mathematical equation that will transform any kind of input into a fixed length output.

The input could be a book, a phone number, any characters, or a picture and movie the output would always be the same length.  

The output is commonly called "Digest" or "Hash' 


Properties that a hash function should have::

Easy to compute: It must be easy and fast for any computer to calculate the output which is the result of that equation.

Deterministic: a given input will always give the same output when the hash function is applied.

Image resistant:  From the output it’s infeasible to  find the input.

Actually with enough computational power and millions of years in front of you could find the input, so we say it’s “infeasible” not impossible.


Collision resistant:  It must be extremely unlikely— in other words, practically impossible— to find two different inputs that produce the same output

If you change any character, even a simple capital letter into a small one the output will look totally different, only the length remains the same.

Hash functions are also called "One way function" because any input will give a fixed length output but from that output it will be practically impossible to guess the input back. 

That property is what is used in blockchain: to link blocks together and to generate public/private keys.  

Evolution in progress...