This monograph describes the principles of information theoretic secrecy generation by legitimate parties with public discussion in the presence of an eavesdropper. The parties are guaranteed secrecy in the form of independence from the eavesdropper's observation of the communication. The focus is on secrecy generation in two settings: a multiterminal source model and a multiterminal channel model, in both of which the legitimate parties are given privileged access to correlated data of which the eavesdropper has only partial knowledge. Part I is concerned with basic technical tools for secrecy generation, many of which are potentially of independent interest beyond secrecy settings. Part II applies the methods of Part I to secrecy generation for the multiterminal source and channel models. Based largely on known recent results, this self-contained tutorial also includes new formulations with associated new proofs.