Quantum Cryptography -- Tight Bounds for Simon's Algorithm -- Constructions for Quantum Indistinguishability Obfuscation -- On Forging SPHINCS+-Haraka Signatures on a Fault-tolerant Quantum Computer -- Post-Quantum Cryptography -- Post-Quantum Key-Blinding for Authentication in Anonymity Networks -- Implementing and measuring KEMTLS -- A Monolithic Hardware Implementation of Kyber: Comparing Apples to Apples in PQC Candidates -- Attribute-Based Access Control for Inner Product Functional Encryption from LWE -- Asymmetric Cryptanalysis -- Classical Attacks on a Variant of the RSA Cryptosystem -- Improved attacks against key reuse in learning with errors key exchange -- Cryptanalysis and Side-Channel Analysis -- Differential-ML Distinguisher: Machine Learning based Generic Extension for Differential Cryptanalysis -- Train or Adapt a Deeply Learned Profile -- Autocorrelations of vectorial Boolean functions -- Automatic Search for Bit-based Division Property -- TEDT2 - Highly Secure Leakage-resilient TBC-based Authenticated Encryption -- Distributed Cryptographic Protocols -- Weight-Based Nakamoto-Style Blockchains -- LOVE a Pairing -- Implementing Secure Reporting of Sexual Misconduct - Revisiting WhoToo -- Stronger Notions and a More E cient Construction of Threshold Ring Signatures -- Improved Threshold Signatures, Proactive Secret Sharing, and Input Certification from LSS Isomorphisms -- Multiparty Computation -- Full-Threshold Actively-Secure Multiparty Arithmetic Circuit Garbling -- The Cost of IEEE Arithmetic in Secure Computation -- Honest Majority MPC with Abort with Minimal Online Communication.

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.