The three-volume set of LNCS 11921,11922, and 11923 constitutes the refereed proceedings of the 25th International Conference on the Theory and Applications of Cryptology and Information Security, ASIACRYPT 2019, held in Kobe, Japan, in December 2019. The 71 revised full papers presented were carefully reviewed and selected from 307 submissions. They are organized in topical sections on Lattices; Symmetric Cryptography; Isogenies; Obfuscation; Multiparty Computation; Quantum; E-cash and Blockchain; Codes; Authenticated Encryption; Multilinear Maps; Homomorphic Encryption; Combinatorial Cryptography; Signatures; Public Key Encryption; Side Channels; Functional Encryption; Zero Knowledge.