101 Blockchains
101 Blockchains

Newbie’s Guide: Private key vs Public Key – How They Work?


Today, we will go through a simple comparison of private key vs public key. Once you understand the difference, you will be able to get a proper grasp of how cryptocurrency works.

When it comes to blockchain or cryptocurrency in general, you should have heard about private and public keys. They are an integral part of any blockchain. Without these, the whole idea will fall off. So, they do? Let’s get started.

Private key vs Public Key

Before we go deep into their comparison, we first need to understand each of them first. In cryptography, and cryptographic algorithm always have two or more keys associated with it. They are private and public keys.

What is a Private Key?

A Private key is a secret key that is used to encrypt and decrypt messages. It is used with the Public key. It needs to be kept private, all-the-time, and should never be shared with anyone.

In cryptocurrency, private keys are used by wallets to protect its asset. As private keys cannot be reversed engineered, they protect your asset without any compromise whatsoever.

For example, Bitcoin wallet has a private key associated with it. When you create a new wallet, both private key and public key are generated along with it. Once you get it, you need to backup your private key to a safe place.

Note: If you lose your private key, you will not be able to access your wallet or its funds. It is always a good idea to back it up either by writing down in private diary or printing it out.

What is a Public Key?

A public key, on the other hand, is only used to encrypt the message. It can be sent to other people for encryption purposes. Once a sender encrypts a message using your public key, you can unlock it only using your private key.

To get a grasp of how these keys work, let’s look at two types of encryption types.

Asymmetric Encryption

Asymmetric encryption works by generating a pair of private/public keys. It is a cryptographic algorithm that lets you send messages. In this algorithm, it is not possible to guess private key from the public key.

Digital signatures are used to share a public key. The private key, on the other hand, is stored safely in the software using encryption.

Symmetric Encryption

Symmetric encryption works on private keys only. This is extremely useful for encrypting data in a server.

Symmetric encryption and asymmetric can work together. For example, an asymmetric encryption is used to send private keys through the network. Once it reaches its destination, the private keys can then be used to decrypt and encrypt data. The private key remains safe as it is sent using asymmetric encryption.

So, how does it work?

The whole process starts when some someone decides to send you coin over blockchain. As a user, you only have access to your private key and public key. The keys are a long sequence of integers and letters. Let’s take a look at the 512-bit encryption key.

KaPdSgVkYp2s5v8y/B?E(H+MbQeThWmZq4t6w9z$C&F)[email protected]!A%D

The key is generated randomly from Encryption Key Generator.

After a transaction is initiated, the blockchain generates a signature to ensure that the transaction goes smoothly with any alteration or double-spending. The signature is then used to confirm the transaction.

Public key encryption

Image Credit: Wikipedia


How the Public Key and Address are Generated

The public key is also generated using the private key. The public key then goes through a one-way hash function which in-turn generates your public address. The public address is visible to anyone and can be shared with anyone to send coins or funds.

It is possible to generate both public and address from the private key. But, the reverse function is not possible. This means that you cannot generate the private key if you have the address or even the public key of a person.

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Technically, it can be reversed, but it would take more than 40e31 (40 followed by 31 zeroes) years to do so using the most powerful computer. That’s not feasible and hence makes the whole process computationally secure.


We hope that our article on private key vs public key helped you to understand how it works. If you are new to cryptocurrency or blockchain, you should learn these concepts and understand the importance of each of them. As a user, you should take care of your private key at all cost. Don’t share it with anyone or you will lose your funds. There are a lot of scams online that will try to ask you for the private key. If you see someone do this, just keep running!

So, what do you think about the whole discussion? Comment below and let us know.

About Author

Nitish holds a BSc in computer engineering. He is a blockchain enthusiast and in spare time likes to read about the moon. His articles have published on Dzone, InfoWorld, and Hongkiat.

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