Final answer:
Public-key cryptography is a cryptographic system that uses two different keys: a public key and a private key. It is used for secure communication over an insecure channel, and it provides encryption, authentication, and confidentiality.
Step-by-step explanation:
Public-key cryptography is a cryptographic system that uses two different keys: a public key and a private key. The public key is used for encryption, while the private key is used for decryption. This system is based on the mathematical concept of asymmetric key algorithms, where it is computationally easy to generate a pair of keys, but extremely difficult to derive one key from the other. This makes it suitable for secure communication over an insecure channel, such as the internet.
Let's say Alice wants to send a secure message to Bob. Bob generates a key pair, which consists of a public key and a matching private key. Bob then shares the public key with Alice. To encrypt the message, Alice uses Bob's public key. This encrypted message can only be decrypted using Bob's private key. This ensures that only Bob can read the message.
Public-key cryptography is widely used in various applications, such as secure email communication (PGP), secure online transactions (SSL/TLS), and digital signatures. It provides a secure method for data encryption, authentication, and confidentiality.