Introduction 

We will have a detailed look at the difference between public key and private key cryptography. We all have seen in the old Bollywood movies when two detectives meet outside on a mission, the first user identification techniques of greeting each other with a code word.

If both use the designated code word, they continue to communicate further. Code words were used in order of protecting sensitive and confidential information. Likewise, in today’s world of the internet, while most of the communication happens digitally, it’s imperative to protect our data and information from cyber-attacks and malign threats. 

Cryptography is the method of conducting a secure communication wherein the sender uses a cipher to add with the plaintext that converts it into ciphertext, and the intended receiver decodes this ciphertext back to plaintext as he has the key. Any interception in this process can be detected. As we have understood so far, cryptography involves two parts namely, encryption and decryption using a cipher aka the key.

A cipher suite uses a unique algorithm for encryption- encoding while sending and uses another algorithm for message authentication at the receiver’s end. The entire process, embedded in protocols and software codes that are written to run operating systems and electronic devices, needs the generation of public and private keys for encryption and decryption.

There are two major types of cryptography; private and public-key cryptography.

  1. What are the public key and private key cryptography?
  2. Difference between a public key and a private key

1. What are the public key and private key cryptography?

Symmetric key cryptography: This is also referred to as private key encryption.  In this type of cryptography, both the sender and receiver use a single key during the communication or transfer of information. The sender uses this key for encrypting plain text and sends the ciphered text to the receiver through the communication channel. The receiver uses the same key for decrypting the ciphered text on the other end. Upon deciphering he recovers the plain text back.

The private key is only known between two people involved in the communication. Private keys are created using the same mathematical algorithm that is used in the public key to create a strong binary sequence that is paired. 

Asymmetric key cryptography: This is also referred to as public-key encryption.  This type of cryptography is also referred to as public-key cryptography. Here we use two related keys; private and public keys. The public key is used for encryption and the private key is used for decryption. Both keys are different, even if the public is known by everyone, only the intended individual will be able to decipher the text as only he has the unique private key. Asymmetric cryptography algorithm is used in WhatsApp communication. 

Although in asymmetric key cryptography, a string of numbers i.e. the public key is available in public, but it can only be deciphered by the individual who has the secret private key. It has an edge over private keys as it provides increased security. This doesn’t sound, right? Let me explain this. In private key cryptography, both parties have access to the secret key making it more susceptible to hacking or increased risk. Moreover, in the case of private key cryptography scalability becomes an issue.

2. Difference between a public key and a private key

A) Speed

A private key is much faster than a public key 

B) Uniqueness

In the case of the private key which is used for symmetric-key cryptography, the same key is used for encryption and decryption of the message during the conversation 

On the other hand, a public key which is used in the case of asymmetric key cryptography uses two keys, one is used during encryption and the other is used during decryption at the receiver’s end. 

C) Secret

In the case of a private key, the private key is known only to the sender and the receiver and to anyone else

In the case of a public key, on the other hand, the key is public and can be viewed by everyone

D) Type of cryptography

A private key is used in the case of symmetric key cryptography wherein one single key is used for transmission between two parties 

In the case of a public key mechanism, there are two different keys used for the transmission. Which public-key is open for everyone to see and the private key is available only between the sender and the receiver. 

E) Purpose

Private key cryptography checks the speed, reliability, and security of the system 

Whereas the public key testing has a long-term view and checks the sustainability of the system 

To put it in simple terms, the major difference between symmetric and asymmetric cryptography is in the key used by the sender and the receiver. If both use the same key for transmission and receiver, then it is Symmetric key cryptography and if they use different keys then it is called asymmetric key cryptography.

One of the most used and seen examples of public-key cryptography is WhatsApp that promises end-to-end encryption. It involves public-key cryptography/ asymmetric key cryptography.  I.e. only the intended individual has the private key. Upon installation of WhatsApp on the devices, public keys are registered with the server and the messages are communicated securely using unique private keys.

With the increasing usage of digital transactions using UPI, digital wallets, internet banking, end-to-end secure payments is a need of the hour. The respective banks and the payment gateways use cryptography for these transactions to avoid the risk of malware and hackers.

Conclusion 

Cryptography has evolved over the years and has become more secure from potential attacks, cyber crimes, threats, etc. Having studied symmetric and asymmetric types of cryptography, we understand that digital transactions are secure as they are encoded through a lock-and-key mechanism of mathematical algorithms. In recent times, to make this process even more secure than before, quantum cryptography is being used.

Wherein a sequence of photons is sent from the sender which goes through a beam or a polarizer that polarizes it into a chain of data. Upon receiving this sequence, the receiver decodes it and sends it back to the sender. Only the photons that are not intercepted are considered for transmission and the rest are discarded in the process. This ensures the safety and protection of confidential data. 

With the increasing advent of digitization and e-commerce, the security of transactions becomes increasingly important. With cryptography is placed the interceptions and potential cyber frauds can be avoided. 

So, have you made up your mind to make a career in Cyber Security? Visit our Master Certificate in Cyber Security (Red Team) for further help. It is the first program in offensive technologies in India and allows learners to practice in a real-time simulated ecosystem, that will give you an edge in this competitive world.

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