Roberto Guimaraes
Senior Software Engineer at Fastly
Denver, Colorado, United States
Summary
🤩
Rockstar🎓
Top SchoolRoberto Guimaraes is a Senior Software Engineer in Denver with 11 years of professional experience focused on large-scale, high-availability systems and low-level networking. He brings deep C/C++ expertise in TCP/IP, advanced socket programming, multithreading, HTTP and TLS/HTTPS, and has shipped production edge-server software at Fastly and high-throughput proxy/DDoS mitigation systems at VeriSign. An active open-source contributor to prominent projects like the H2O HTTP server and picotls, he has improved TLS session resumption, handshake error handling, and OpenSSL interoperability—work that demonstrates rare, practical mastery of SSL/TLS internals. Comfortable across the AWS/CICD toolchain and scripting with Lua and Ruby, he pairs systems-level rigor with automation skills, and is currently expanding into Go. Notably, he co-authored performance-critical networking components earlier in his career (Internet Page Accelerator) that optimized HTTP over satellite links, reflecting a long-standing focus on real-world, high-latency environments.
11 years of coding experience
16 years of employment as a software developer
Bachelor's degree, Computer Science, Bachelor's degree, Computer Science at Universidade do Vale do Rio dos SinosSpecialization Graduation, Specialization in Information Systems and Telecommunication, Specialization Graduation, Specialization in Information Systems and Telecommunication at Federal University of Rio Grande do Sul
English, Portuguese
Stackoverflow
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0reached
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Github Skills (15)
c1710
mtls10
ss10
network-security10
sslv310
ssl10
tls1210
c1110
openssl10
network-programming10
cryptography10
tls1310
libtls10
security10
performance-optimization9
Programming languages (2)
Github contributions (5)
h2o/h2o
Jul 2016 - Jan 2023
H2O - the optimized HTTP/1, HTTP/2, HTTP/3 server
Role in this project:
Back-end Developer & Security Engineer
Back-end Developer & Security EngineerContributions:16 reviews, 20 commits, 11 PRs in 6 years 7 months
Contributions summary:Roberto primarily focused on enhancing the security and performance of the H2O server. Their contributions include implementing TLS improvements, such as sending TLS alerts on handshake errors and optimizing session resumption using the OpenSSL library. Additionally, the user addressed OpenSSL-related issues, including migrating to newer APIs and ensuring compatibility across different versions of the library, contributing to the overall stability and security of the server. The commits show strong expertise in SSL/TLS protocol and low-level network programming.
h2ohttp-clientfiddlerhttp2optimized
h2o/picotls
Jan 2019 - Feb 2021
TLS 1.3 implementation in C (master supports RFC8446 as well as draft-26, -27, -28)
Role in this project:Back-end Developer
Back-end DeveloperContributions:9 reviews, 14 commits, 7 PRs in 2 years 1 month
Contributions summary:Roberto primarily focused on enhancing the picotls TLS 1.3 implementation in C. Their contributions include adding callbacks for extension decoding, incorporating client cipher suite information, and improving the handling of early data within the TLS handshake. These modifications involve updating and extending existing structures and functions within the picotls library to support various TLS features. The user also made adjustments related to session ticket handling.
cryptographysslocsptlsmaster
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