This document provides information on public key encryption. It discusses how public key encryption uses a public key for encryption and a private key for decryption. It also describes how the Diffie-Hellman key exchange algorithm works, including how two parties can generate a shared secret key over an open channel by exchanging public values and performing calculations. An example of the Diffie-Hellman algorithm is also provided. The document concludes by listing some applications of public key encryption like confidentiality and digital signatures, and also discusses some weaknesses like vulnerability to brute force attacks.