Difference Between Public Key and Private Key in Blockchain

April 10, 2023

Blockchain Basics Introduction to Blockchain Technology

Difference Between Public Key and Private Key in Blockchain

Public key is truly public and can be shared widely, while private key should be known only to the owner. Know more the difference between public key vs private...

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Table of Contents

Introduction

Everything from the exchange of data to the transfer of funds to looking up information to getting driving instructions – the internet makes all of this easy. However, with that come safety concerns. How do we ensure that the data we are transferring is not getting into the wrong hands? How do we make sure that the information being sent is free of any third-party intervention? Answering such questions isn’t as difficult as it used to be, especially with the advent of technologies like blockchain, encryption, decryption, etc.

Data protection is extremely necessary while sending and receiving information to make sure that it hasn’t been tampered with. One way to do this is by encryption and decryption through public and private keys. What is the difference between private key and public key anyway? We find that out in this post, but first, let’s see the definitions.

So, what are public and private keys?

What is a Public Key?

Before getting into the technicalities, let’s answer the very basic question first. What is a key? In cryptography, a key refers to a string of alphabets or numbers saved in a file, which, when processed through a cryptographic algorithm, facilitates the encoding and decoding of data. There are two types of keys: public and private.

A public and a private key are required to safely encrypt data being exchanged between two parties. A public key is used to encrypt the information into ciphertext, and after it is relayed to the receiver, they use the private key to decrypt the message, which is why this process is known as asymmetric cryptography as well. Some applications of public key encryption are:

Encrypting emails to keep the contents confidential
Used in SSL protocol to establish secure connections to websites
Used in blockchain and cryptocurrency
Creating digital signatures in operating systems.

How Do Public Keys Work?

Public key encryption is a slightly more complex process because of the fact that two different keys are involved. The most common algorithms to generate public keys are:

Rivest- Shamir- Adleman (RSA)
Elliptic Curve Cryptography (ECC),
Digital Signature Algorithm (DSA).

These algorithms are used to generate alphanumeric strings with different sizes as per the gravity of the information being shared.

The public key is for the world to see, but the private key paired with it should never be shared with anyone other than the concerned parties. The public keys are generated with an expiration date, which means after it expires, no data can be encrypted using the said public key, though the private key of the pair will keep decrypting the information.

What is a Private Key?

A private key (or secret key) is a key that can be used to both encrypt and decrypt data. The sender and receiver will have the same key that will be used to encode the message before sending it forward, as well as used to decode it after receiving it on the other side. It is called ‘symmetric,’ based on the fact that the same key is used on both sides. The complexity and length of a private key determine how safe a certain encoded piece of data is and how susceptible it is to a brute-force attack.

How Do Private Keys Work?

Private keys play a pivotal role in symmetric encryption, and here’s how it works:

Before every encryption process, it is essential to generate a new key. Make sure it is as random as possible and can’t be figured out through trial and error.
After generating the key, store it very securely, preferably offline. However, it can also be saved on the computer used for the encryption and decryption process with a password. It is important to keep the keys safe, as losing them will mean losing access to the encrypted data.
The private key is used on both ends of the process; by the sender while encryption and by the receiver during decryption. Hence, it must be shared securely and only among the parties authorized to access the data.
It is advised to use cryptographic software to automate this whole process, along with private key management, which is used to make sure that no individual key is used for a prolonged period of time and is retired after a certain period.

Difference Between Private Key and Public Key

After establishing what are public and private keys, let’s dive into the difference between private keys and public keys. Here’s a comparison chart that establishes the differences between the two encryption systems:

Features	Public Key	Private Key
Definition	Public key encryption is the process where a pair of public and private keys is used to encode and decode data.	Private key encryption is a process that uses a single key, also known as a secret key, to encode and decode data.
Type	It is also known as asymmetric encryption, as two different keys are used for different purposes.	It is also known as a symmetric encryption algorithm, as a single key is shared for encryption and decryption purposes.
Sender/Receiver Dynamic	The sender and receiver don’t use the same key. The private key is shared by the sender with the receiver.	The sender and receiver employ the same key for both encoding and decoding purposes. The key is shared with the receiver securely.
Performance	The sender and receiver don’t use the same key. The private key is shared by the sender with the receiver.	The private key encryption is faster as the same key is used throughout.
Secrecy	The public key is visible to everyone.	The private key is supposed to be stored securely and is to be shared only with the concerned parties.
Key loss	As the key is public, it is not likely to be lost.	Losing the key is likely, so it should be stored securely, preferably offline, as losing it means losing access to the encrypted data.

What are the Examples of Public and Private Key Encryption?

The Diffie–Hellman key exchange is an example of public key encryption. It is a method to exchange cryptographic keys safely over a public channel. It was the idea of Ralph Merkle and was named after Whitfield Diffie and Martin Hellman. Earlier, the only way to share keys was to get them delivered in person through a trusted middleman. Diffie-Hellman allowed two parties to establish a shared secret key over a secure channel. Multiple services based on the Diffie-Hellman key exchange have been proposed, including the ElGamal encryption.

Another example of a public key cryptosystem is RSA (Rivest Shamir Adleman), used for secure data transmission. A user creates a public key based on two large prime numbers and an auxiliary value. The prime numbers are to be kept secret while the rest goes public. Anyone can encrypt the message using the public key; however, only a person with knowledge of the prime numbers can decode the message.

On the other hand, if you have used Microsoft Word to encrypt a document, you have used private key encryption.

What are the Business Benefits of Public-Private Key Encryption?

Using public-private key encryption has its business benefits as the recipient can be sure of the fact that the data that has been sent hasn’t been compromised and tampered with.

1. Confidentiality

The public-private key encryption works on the principle that the encrypted data that has been sent can only be accessed by the recipient. To ensure that the information’s confidentiality hasn’t been compromised, the encryption takes place through the public key and the recipient decodes it with a private key that only they can access. This process ensures that there is no third-party intervention and only the intended recipient can decode the information that has been sent.

2. Integrity

The encryption and decryption process has more to it than you might think. As a message gets decrypted, there’s another process that takes place which requires checking that the received message is the same as what was sent. It ensures the integrity of the message and the fact that it hasn’t been tampered with in transit.

3. Authenticity

When a message is sent by the first party, it is signed by their private key. The only way for the second party to decrypt it is by accessing the former’s public key. By signing their message with their private key, the first party ensures the message was authentic and really came from their side. A public-private key pair ensures that the authenticity of a message is maintained as it is forwarded from the sender to the receiver.

Conclusion

With the advent of technology in all spheres of life, it is essential to ensure that our information doesn’t fall into the wrong hands. It has become more important than ever with digital currencies and finance management processes going online. One way to ensure safety is by encryption and decryption through public and private keys.

We hope this post has successfully explained to you the distinctions between public key vs. private key.

Frequently Asked Questions (FAQs)

1. What are a Public Key and Private Key with Examples?

Public key encryption refers to a process where a pair of public-private keys is used to encrypt and decrypt information. For example, Bob needs to send Alice a message that someone else shouldn’t read. For that, Bob will use Alice’s public key to encrypt the message and will send it to her.

Alice will use her own private key to decode the message. In this process, the public key is known to all, but the private key is not shared with anyone other than the recipient. It is also called asymmetric encryption because different keys are used for different purposes. Private key encryption is a process where the same key is used to encrypt as well as decrypt the message.

2. What are Public Key and Private Key in Cryptography?

A key in cryptography is a complex series of numbers and alphabets, which can help encrypt or decrypt data when processed through a cryptographic algorithm. The two kinds of keys in cryptography are public keys and private keys. The public key is used to encrypt information and subsequently forward it to the recipient.

On the other hand, the private key is used by the recipient to decrypt that very information. Where the public key is visible to all, the private key is to be stored safely, ensuring that no second party has access to it.

3. What is the Difference Between a Private Key and a Public Key?

Here are some of the differences between private and public keys:

Public key encryption requires a pair of public and private keys to encode and decode data, whereas private key encryption requires only one key for both encryption and decryption.
The public key is also known as asymmetric encryption, as different keys are used for both encoding and decoding. The private key is known as symmetric encryption because the same key is being used for both said processes.
The public key is visible to everyone, but the private key is supposed to be stored safely and is to be shared with the concerned parties only.
The public key is visible to everyone. However, the private key is to be stored safely, as losing it would mean losing access to your crypto.

4. How Does Public Key and Private Key Work?

A public key is a string of alphanumeric codes, generated by algorithms. It is used to encrypt information which can later be decrypted by a private key. In public key encryption, both of the said keys are used for two different purposes, however, in private key encryption, one single key is used for both encryption and decryption.