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Public Key Encryption – What Is It & How SSL/TLS Certificate Uses to Provide Secure Connection?


  • Two types of encryption are often mentioned, and among them, popular and more secured is public-key encryption.
  • Private Key encryption uses one key called Private Key.
  • Public Key encryption uses two keys – Public & Private keys.
  • Public Key Encryption works with SSL/TLS protocol for delivering end-to-end encrypted connection.

How SSL/TLS Certificate Uses Public Key Encryption to…

Nowadays, technology has evolved tremendously.

Online financial transactions and the passing of sensitive information is quite the norm.
With such advancement, security issues are arising. You’re also aware of it.

Along with new online security advancement, one of the old age securities which accompanied till now is encryption – one of the cryptography schemes where the mathematical function is used for encrypting data into an unreadable format, which can only be decrypted by an intended party.

Generally, two names arise when it comes to encryption:

  • Private Key Encryption (Symmetric Encryption) – Not so popular.
  • Public Key Encryption (Asymmetric Encryption) – Popular, widely used, and the one which we’ll discuss in detail.
In this article, you’re going to learn what private key encryption is. What’s public key encryption, how does public-key encryption works, and how SSL/TLS certificate makes use of it to provide secure connection so you can transfer your sensitive information over the internet without being worried about any security threat?

What’s Private Key Encryption?

If you look in history, you’ll find that private key encryption is used back from 1900 BC. In Private key encryption, both the parties – the one who’s encrypting the data and the one who decrypts the data, shares one single key, which is used for enciphering as well as deciphering the data. Some of the popular examples include Ceaser’s cipher, Louis XIV’s Great Cipher, and the Enigma machine.

Problem With Private Key Encryption

Private Key encryption i is a type of encryption where a single private key is used for encrypting as well as decrypting information, which makes it fast compared to Public key encryption. Though, security issues shouldn’t be overlooked as protecting one single key creates an issue in management as everyone has the same private key.

For example, if both parties must have a physical key and if there’s a distance between them, which is quite common, then you’ve to trust a courier with your private key. And if anything goes wrong in-between for instance, the private key gets in wrong hands then within a matter of time everything could be tumbledown.

Even in today’s digital world, private keys have their issues when it comes to the distribution of keys. For example, how anyone can be sure that an intended party is sending the private key to the right party without any mechanism to authenticate it.

The Invention of Public Key Encryption

Public Key Encryption is one the encryption technique which was discovered twice. Firstly, in 1970 James Ellis, a known cryptographer of the UK’s Government Communications Headquarters (GCHQ) on theory, made a public key encryption system but couldn’t move further as he wasn’t aware how to implement it.

Later in 1973, Clifford Cocks came out with an implementation method by mixing an algorithm that was quite similar to what we say RSA. Also, another mathematician Malcolm Williamson developed a key exchange system similar to a cryptographic key exchange method Diffie-Helman.

Again, in 1976 Martin Hellman and Whitfield Diffie discovered Public Key Cryptography. They’re the one on whom system was named after (in 2002 they even argued that it must be named Diffie-Hellman-Merkle key exchange, as a cryptographer named Ralph Merkle has also worked with them at Standford.)

Lastly, a year later, Ron Rivest, Adi Shamir, and Leonard Adleman created the RSA, which got finalized at MIT.

What Is Public Key Encryption?

RSA and Diffie-Helman were asymmetric cryptosystems (public-key encryption), which is the correction of an age-old problem related to the key distribution of Private Key Encryption.
how public key encryption works
Public key encryption, often called Asymmetric encryption, uses two different keys for encrypting the data. Here, one key is used for encrypting, and another one is used for decrypting that same data. There are two keys – Private and Public keys, so the data which is encrypted using a Public Key will be decrypted using the Private Key.

Here, the benefit is that communication goes only one way with the Public Key encryption. Henceforth, it’s also known as “asymmetric.” Here, the authorized party has the private key, which must be kept securely, and the public key, as the name implies, remains public to everyone – doesn’t carry the risk of compromise as it’s worthless even if it gets in wrong hands.

How Does Public Key Encryption Works?

Public key encryption lets you deliver message secretly to anyone that has published their public key, and only an intended recipient of that message can decrypt it. It’s the way a safe, secure system is set up for exchanging messages.

In public-key encryption, the user is allowed to create a public and private key. Here, both the key are connected through large chunks of numbers and mathematical functions. And, the decryption of an encrypted message sent by another user is carried out by the system through matching its related public key of the user’s private key.

Essential Characteristics of a Public Key Encryption System

  • For encryption and decryption of the data, different keys are used.
  • Every received message is equipped with a unique decryption key called a private key.
  • The key that’s published by the receiver is called the public key.
  • The public key can be shared among anyone for allowing it to encrypt the message and authenticate the digital signature. However, as said earlier, the private key is kept secret, and only the holder of the private key (an intended party) is capable of decrypting that message while generating a digital signature.
  • It’s impossible to determine the Decryption key (private key).

Is Public Key Encryption Superior?

Yes, compared to Private Key Encryption, its better. Public Key encryption encrypts data asymmetrically, due to which it’s quite difficult to crack the same data, which was encrypted with the help of symmetric or say private key encryption.

Though, the security of asymmetric keys shouldn’t be judged as per the length. Metrics of the key, along with the ease of distribution and involved computation, play an essential role in the success of creating a secure key.

On the other hand, Symmetric encryption uses the same key for both encryptions as well as decryption due to which it becomes less secure, as there are higher chances of losing a key and third-party accessing it.

How SSL/TLS Uses Public Key Encryption?

SSL/TLS (Secure Socket Layer / Transport Layer Security) is one of the security protocols which provide encrypted communication throughout a network. In today’s date, it’s an essential and mandatory security layer for the entire website because of the security framework it offers. SSL uses public-key encryption, also called asymmetric encryption. Aside from public-key encryption, this SSL/TLS protocol also benefits using the X.509 certificate for authenticating users who also provides absolute confidentiality and integrity.

How Does SSL/TLS Protocol Work With Public Key Encryption?

In the SSL/TLS protocol, Public Key Encryption is helpful by offering key exchange and authentication. Its best example can is with the TLS 1.3 cipher suites – algorithms used for encryption. To be precise, the SSL/TLS protocol uses the Asymmetric encryption algorithm for establishing a secure client-server session. Once the sender sends the public key for data encryption, the receiver decrypts that message using Private Key.


In today’s technology evolving world, where all data are available online over the internet – personal and professional. It’s of utmost importance to have end-to-end data security in place for avoiding becoming a target of malicious hackers and other online threats that happens daily.

Public Key encryption is like a boon for ensuring the privacy and integrity of the data. And, if it’s applied properly, it can help you stay safe and secure from most of all the data security-related threats that linger around on the internet.

Important Resources to Read

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