This book constitutes the refereed post-conference proceedings of the 5th International Conference on Cryptology and Information Security in Latin America, LATINCRYPT 2017, held in Havana, Cuba, in September 2017.The 20 papers presented were carefully reviewed and selected from 64 submissions. They are organized in the following topical sections: security protocols; public-key implementation; cryptanalysis; theory of symmetric-key cryptography; multiparty computation and privacy; new constructions; and adversarial cryptography.