The two-volume set of LNCS 11239 and LNCS 11240 constitutes the revised proceedings of the 16th International Conference on Theory of Cryptography, TCC 2018, held in Panaji, India, in November 2018.The total of 50 revised full papers presented in the proceedings were carefully reviewed and selected from 168 submissions. The Theory of Cryptography Conference deals with the paradigms, approaches, and techniques used to conceptualize natural cryptographic problems and provide algorithmic solutions to them and much more.