Cryptography (noun):
Known as the art form which encrypts important messages so that no one between the sender and the receiver can read the message.
It was used in the past between militaries and their generals to pass critical information without enemy forces deciphering what was being communicated. Little did they know that we would science it all up to make a complicated version of ourselves.
What‘s its use in Blockchain？Since the network is distributed and used by almost everyone around the globe, your information is bound to be at the risk of being stolen or manipulated, especially sensitive ones such as bank account details or where you have stashed that extra cash in your house (hint: it’s always under the mattress).
Enter Public Key Cryptography. It is one of the techniques of Cryptography and forms the foundation upon which the decentralised system of Blockchain relies. We can create and store verifiable records of transactions on the network with the use of Public Key Cryptography.
Now onto the best part. Learning how it works.
How to use it in Blockchain？You will have two keys. A Public key and a Private key. They function as a lock and key. The public key encrypts any message sent on the network and the private key (you guessed it right) decrypts it. However, only those messages encrypted by your Public key are decrypted by your Private key.
The public key can be shared with anyone to encrypt messages. Thus the reason why it‘s called that. But a Private key can’t be shared with anyone as it can be misused, so you have to keep it as hidden as you can.
Keys in actionSo lets create a scenario where you want to ask your friend when they are going to return your expensive watch they borrowed for an occasion. But for fun purposes, you decide to send them a message through the Blockchain network.
Now, you would write your message and then use your friends public key, which they shared with you, to encrypt the message. This would result in a ciphertext or something that your kid types when he gets hold of your phone. After receiving the message, your friend would decode it with their private key and would find your message in its original form.
This is how important communication travels back and forth on the network. Everyone else only sees some gibberish but only you two whats being said. Like only you knew from the message sent back, that your beloved buddy broke your watch, being the clumsy guy that he is.