So,how cryptography continue to works on blockchain?

The most used cryptography in blockchain is the encryption.
In bitcoin it uses the SHA-256.

The purpose of the encryption is to convert a large data into a short numbers( hash) and
to make the the encrypted message can be decrypt by the sender and receiver.

Just imagine the message in your Gmail is only known by you and your receiver/sender, Google company has no authorization to access to the information of those mails.

Next, due to it's peer-to-peer network, all the onchain information need someone to verify to proof them valid,
which mining algorithm has been introduced such as PoW, PoS, DPoS and so on.

Bitcoin uses Proof-of-Work as their algorithm in order to verify all these transaction message or 'email'

For example Alice send Bob 1.0 btc:
In traditional banks, the bank will deduct 1 btc from Alice and add 1 btc to Bob's account.

But it is different in blockchain since we do not have a bank to become our trustee.

So, miners from all around the world will act as the bank, but a decentralized way.
As in All of the miners will compete together to decrypt the information which in stored in a 'block'

Just assume all the emails has been packed in a bundle and waiting to be verify

the miners will then start to scan through the latest to-be-verified block and find out the mathematical equation of the answer.

E.g.
If a question is given in '1+1=' , we know the answer will be '2' right?
What if the question is given in '2=??'

The miners will need to find out the exact equation the has the answer of '2'
so what can they do is to brute force it, which means try to crack it 1 by 1

with the computing power available these days, this is considered easy isn't it?
Of course there are certain rules will be need to fit in order to decrypt the block and it will not be discussed today.

So to conclude the message for this post,
We started to understand why bitcoin needs miners in order to make the blockchain works.

In short, blockchain has it own fixed protocol to encrypt the message, and in a public chain, we will need the help from community around the world to verify it.

Hope this helps!