What are the functions of Public key Cryptography?

Public-key cryptography is also known as asymmetric cryptography. It is a form of cryptography in which a user has a set of cryptographic keys including public key and a private key. The functions of Public key Cryptography are as follows −

Encryption − The encryption application supports the confidentiality and integrity security services for the information. The public key supports the security services including authentication and non-repudiation.

Encryption can be used to transform the plaintext message into unreadable format with the support of a key, again the message transform back to original message by using the decryption procedure.

In this process, each user encrypts the message with the receiver’s public key. The encrypted message is decrypted by only the receiver’s private key. Let us suppose a user B’s private key is PrvB and public key is PubB. If user A need to send a message M to user B. First the message M is encrypted by the public key of user B and send it to user B. Then that encrypted message is decrypted by the private key PrvB of user B.

Digital Signature − Digital signature is used to sign the message to validate the message sender in the network. For example, if user A need to send a message M with its digital signature to user B. First, user A signs the message with his/her private key PrvA. The signed message sends to user B without implementing any encryption on the message. After taking the message, user B checks the signature of user A with the public key PubA.

Digital signatures are very beneficial in online applications. It supports the authentication and security of a user. The digital signatures are generated by user’s private key and also implement hashing on the encrypted information. The encrypted information define that the digital signature is checked by the public key of the concerned user.

Certificate − Digital certificates are used to validate the public key of a user. In public key cryptography, there is possibility that public key of a user can be changed by an attacker in the network. It can prevent the authentication problem of public key digital certificates are produced.

Digital certificates are calculated in the format of x.509 format. It is the standard format acknowledged in the Public-Key Infrastructure (X.509) has suitable the standard to the more flexible organization of the Internet.

Each user generates its public key and private key. The private key is supported as secret at the user and public key is received in the network. Since host the public key in the network, each user requests a certificate authority (CA) to issue a digital certificate for its public key. Digital certificate includes data such as user’s public key, user name, user signature, validity etc.