I am a PhD student at the Computer Security Lab of the Universidade Federal de Santa Catarina, researching novel combinatorial (un)ranking algorithms to generate random objects in quantum-safe cryptosystems.

On a personal note, I’m enthusiastic about astronomy, immersive sim games, IBM keyboards specifically older than myself and most songs with a saxophone line. 8)

Publications

I am interested in quantum-safe cryptosystems and their applications, particularly hash-based signatures.

Click to see a list of works I have (co-)authored.
J. P. C. Barbosa, G. Zambonin, T. B. Idalino, R. Custódio. From ElGamal to Lattice-Based: Enhancing the Helios Voting System with Quantum-Safe Cryptography. ACNS 2025, pp. 29–49, jun. 2025. 📃 💽
L. G. Rosa, G. Zambonin, J. E. Martina. Enhanced SIM Swap Security Practices via Ceremony Modeling. AINA 2025, pp. 201–211, apr. 2025. 📃 💽
A. B. Kamers, P. O. Abel, T. B. Idalino, G. Zambonin, J. E. Martina. Practical algorithms and parameters for modification-tolerant signature scheme. SBSeg 2024, pp. 522–537, set. 2024. 📃 💽
G. C. Biage, G. Zambonin, T. B. Idalino, D. Panario, R. Custódio. A concrete LIP-based KEM with simple lattices. IEEE Access 12, pp. 16408–16420, jan. 2024. 📃 💽
L. Mayr, L. Palma, G. Zambonin, W. Silvano, R. Custódio. Monitoring key pair usage through distributed ledgers and one-time signatures. Information 14, no. 10, pp. 523–537, sep. 2023. 📃
L. P. Perin, G. Zambonin, R. Custódio, L. Moura, D. Panario. Improved constant-sum encodings for hash-based signatures. Journal of Cryptographic Engineering 11, no. 4, pp. 329–351, jun. 2021. 📃 💽
G. Zambonin. On the randomness of Rainbow signatures. Master's thesis, Universidade Federal de Santa Catarina, oct. 2020. 📃 💽
G. Zambonin, M. S. P. Bittencourt, R. Custódio. Handling Vinegar Variables to Shorten Rainbow Private Keys. AFRICACRYPT 2019, pp. 391–408, jul. 2019. 📃 💽
L. P. Perin, G. Zambonin, D. M. B. Martins, R. Custódio, J. E. Martina. Tuning the Winternitz Hash-Based Digital Signature Scheme. ISCC 2018, pp. 537–542, jun. 2018. 📃 💽
G. Zambonin. Otimização de desempenho do esquema de assinatura digital Winternitz. Bachelor thesis, Universidade Federal de Santa Catarina, jun. 2018. 📃 💽

Professional experience

I also work as a consultant, helping private and public institutions to solve complex problems related to information security.

See details about my previous experience here.

Before starting my PhD, as part of the Computer Security Lab, I mainly worked in the reference implementation and technical specifications of the Brazilian Digital Signature Standard.

  • [Jan/2020–Feb/2024] Technical lead and researcher Supervised research and development efforts to add support for quantum-safe cryptography, JAdES and trusted lists to current standards, as well as further development of desktop, web and mobile tools used in the Brazilian Public-Key Infrastructure (ICP-Brasil) to generate and validate digital signatures.
  • [Jan/2018–Dec/2019] Software developer and systems administrator Led a major development effort towards modernizing the official digital signature validation tool of ICP-Brasil, that resulted in a responsive new web interface, an API that enables headless/batch signature validation, enforced automated unit testing and continuous deployment practices.
  • [Nov/2016–Dec/2017] Junior software developer Developed a proof-of-concept signature validation module for PDF.js and a small library able to easily customize and instantiate most artifacts in a public-key infrastructure.
  • [May/2016–Oct/2016] Junior software developer Implemented support for CMS signatures (attached, detached or embedded in PDFs) in the official digital signature validation tool of ICP-Brasil.

Some details about my consulting work are given below.

  • [Apr/2024–Today] Consultant on digital signatures In partnership with the National Operator of the Civil Registry of Brazil. I design and develop solutions to enhance digital signature adoption in civil registration and notary public processes.
  • [Sep/2022–Mar/2023] Consultant on trusted lists In partnership with the Electronic Government Network of Latin America and the Caribbean (Red Gealc). Developed tools to assist the usage of digital signatures in cross-border operations via trusted lists, pursuant to ETSI standards. 🔗 🔗 🔗
  • [Jan/2022–Mar/2022] Consultant on digital signature standards In partnership with private companies. Developed a tool to validate digital diplomas, and accompanying files, according to the standards maintained by the Ministry of Education of Brazil.
  • [Dec/2020–Mar/2021] Computer forensic examiner In partnership with an intelligent transportation systems company. Processed a complex dataset with native GNU/Linux tools and used statistical techniques to verify the accuracy of the classification of pictures taken by speed enforcement cameras.
  • [Oct/2018–Nov/2020] Security ceremony agent In partnership with several Brazilian public institutions. Provisioned secure servers to run online elections through the end-to-end verifiable voting system Helios, with reduced need for human-computer interaction.
  • [Sep/2018–Mar/2019] Researcher of quantum-safe blockchain protocols In partnership with a novel blockchain platform. Co-developed a protocol to quantum-proof a blockchain, with secure substitution of wallets, replacement of cryptographic algorithms and zero downtime for the platform.
  • [Sep/2017–Apr/2018] Computer forensic examiner In partnership with an intelligent transportation systems company. Built a time series from various evidence sources forming a complex dataset, used to ascertain the authenticity and accuracy of pictures taken by speed enforcement cameras.

Academic activities

I frequently look forward to complementing my research & development work with other exciting projects.

This is mostly for my own record, but feel free to check it out.
Research visits
Teaching assistantships
  • [Mar/2025–Jul/2025] INE5448 - Special Topics in Technological Applications I Class no. 08208, Computer Science @ UFSC.
  • [Aug/2019–Nov/2019] INE410134 - Post Quantum Cryptography and Computation Class no. 41000025DO/ME, Graduate Program in Computer Science @ UFSC.
  • [Aug/2018–Dec/2018] INE5601 - Mathematical Foundations of Informatics Class no. 01238A, Information Systems @ UFSC.
  • [Mar/2015–Jul/2015] INE5405 - Probability and Statistics Class no. 02208A, Computer Science @ UFSC.
  • [Aug/2014–Dec/2014] INE5405 - Probability and Statistics Class no. 02208A, Computer Science @ UFSC.
Involvement in BSc theses
Talks
Service
  • [May/2019–May/2020] Student representative, Deputy and Full Councils of the Graduate Program in Computer Science at UFSC Elected by peers to be a member of the legislative bodies of the Program. Part of the Scholarships Committee.
  • [Sep/2019–Oct/2019] Student member, Electoral Commission for election of Director and Associate Director of the Graduate Program in Computer Science at UFSC Audited the election and verified its results for the 2019–2021 term.
  • [Apr/2018–Dec/2018] Co-organizer, 19th Biology Academic Week at UFSC Developed an attendance system to accurately provide certificates to students and community.
  • Peer review in Designs, Codes and Cryptography and LATINCRYPT 2023.