This book constitutes the proceedings of the 7th International Conference on Cryptology and Information Security in Latin America, LATIN 2021, which was held in October 2021. The conference was originally planned to take place in Bogota, Colombia, but changed to a virtual event due to the COVID-19 pandemic. The 22 full papers included in this volume were carefully reviewed and selected from 47 submissions. They were organized in topical sections as follows: quantum cryptography; post-quantum cryptography; asymmetric cryptanalysis; cryptanalysis and side-channel analysis; distributed cryptographic protocols; and multiparty computation.