Basics of cryptography
Public Key Cryptography

The cryptographic systems based on public key evolved to address the security issues posed by symmetric cryptosystems. This method solves the problem of secret key cryptography by using two keys instead of a single key. Public key cryptography uses a pair of keys. In this process, one key is used for encryption, and the other key is used for decryption.

This process is known as public key cryptosystem (also denoted as cryptography) or asymmetric cryptosystem because both the keys are required to complete the process. These two keys are collectively known as the key pair. In asymmetric cryptography, one of the keys is freely distributable. This key is called the public key and is used for encryption. Hence, this method of encryption is also called public key encryption. The second key is the secret or private key and is used for decryption. The private key is not distributable. This key, like its name suggests, is private for every communicating entity. It is important to point out that the public and private keys are related, but it is virtually impossible to deduce the private key if you know the public key.

The most common public key algorithm is RSA, which name is created as an abbreviation of the first letters of its authors’ surnames; Rivest, Shamir, Adleman.