Public Key Cryptography

Related Concepts

Asymmetric Cryptography; Digital Signature Schemes; Key Agreement Schemes; RSA Encryption Scheme

Definition

Public key cryptography is a method to encrypt messages using a non-secret key. The term public key cryptography also includes various others cryptographic methods using a non-secret key, such as Authentication, Digital Signature Schemes, and Key Agreement. In this section, public key encryption schemes are described.

Background

Conventional cryptography, also known as Symmetric Cryptosystem, uses a secret key to encrypt a message; the same key is required to decrypt the encrypted message. Therefore, the sender and the receiver of encrypted message either had to agree on the secret key before encrypting the message, or the receiver had to learn the secret key before decrypting it. The same secret key could not be used when sending a message to a different receiver. How to manage secret keys was a serious problem before public key cryptosystem was invented.

Theory