This book constitutes the proceedings of the 12th International Conference on Security and Cryptography for Networks, SCN 2020, held in Amalfi, Italy, in September 2020*.The 33 papers presented in this volume were carefully reviewed and selected from 87 submissions. They are organized in topical sections on blockchain; multiparty computation; oblivious RAM; primitives and constructions; signatures, encryption, and algebraic constructions; symmetric crypto; theory and lower bounds ; zero-knowledge.

*The conference was held virtually due to the COVID-19 pandemic.