What is Public Key Cryptography?

1 What is Public Key Cryptography?

Public key cryptography or asymmetric cryptography is an encryption technique that used two pairs of keys that are named as a public key and a private key.

In public key cryptography (PKC), the public key is used to encrypt the message and it can only decrypt by the private key.

Public key cryptography (PKC) is more robust and can not be breakthrough by any third party security breach attempts.

PKC enables the confidentiality, data integrity, authentication and non-repudiation for secure communication.

2 How Public Key Cryptography Work?

As public key cryptography works on the basis of two key pairs which are named as the public key and private key. These key pairs are formed in such a way that the private key can never be obtained from the public key.

Now, the public key is known to everyone, so the sender can encrypt the message by using the receiver’s public key.

But the private key is only known to the receiver who can use it to decrypt the message of the sender. This means the third parties can never obtain the original message even after they got the encrypted message of the sender because they do not have any access to the private key.


 RSA (Rivest-Shamir-Adleman) is the most commonly used algorithm for generating key pairs in public key cryptography.

Generally, RSA mathematically generates two key pairs where one is the private key which is kept secret by the owner and another one is the public key which can be shared to anyone.

3 Applications of Public Key Cryptography

  • Confidentiality: As the message encrypted with the public key and can only be decrypted with the receiver’s private key which is only known to the receiver that makes it impossible for others to view the original message.
  • Authentication: Every individual has its own unique private key by which the message is signed. It can be proved easily that the message belongs to the original sender or not.
  • Non-repudiation: Everyone has their unique and separate private key used for signature so someone can’t say later that the signature was not applied by him.
  • Digital signatures: As the message is signed by the individual’s private key so it can be verified by the public key of him.
  • Encryption: As the message is encrypted with someone’s public key so only that person can decrypt the message using his/her private key.