Cryptography is the practice of secure communication in the presence of third parties. It is also referred to as “secret writing”. Cryptography has been used for centuries to protect important information from prying eyes. In recent years, it has become increasingly important in the digital age, as we rely more and more on electronic communications.

Cryptography is divided into two categories: symmetric-key cryptography and public-key cryptography. Symmetric-key cryptography uses the same key for both encryption and decryption. This type of cryptography is also called “secret-key cryptography”. Public-key cryptography uses two different keys: a public key and a private key. The public key can be shared with anyone, while the private key must be kept secret.

Public-key cryptography is more secure than symmetric-key cryptography, because it is much harder to crack the code using only the public key. In fact, it is virtually impossible to do so without knowing the private key. This is why public-key cryptography is often used for encrypting files and messages.

The most common type of public-key cryptography is RSA (Rivest, Shamir, Adleman), which was first proposed by Ron Rivest, Adi Shamir and Leonard Adleman in 1978. RSA was the first publicly accessible cipher that had a solid proof of security.