Klas Lindfors
Senior Principal Engineer at Yubico
Stockholm, Stockholm County, Sweden
Summary
👤
Senior🎓
Top SchoolKlas Lindfors is a Senior Principal Engineer with 15+ years of experience bridging systems engineering, embedded firmware and cryptographic security, currently leading firmware development for YubiKey and YubiHSM. He combines low-level C and APDU expertise with backend and integration skills, having improved Secure Channel Protocol handling in JavaCard tooling and hardened Yubico's PAM and U2F host libraries. His background includes systems architecture for complex web applications at Stockholm University and early tactical telecom instruction in the Swedish Armed Forces, reflecting a pragmatic, security-first mindset. A hands-on open-source contributor, he has made notable fixes to GlobalPlatformPro and core Yubico projects that strengthen device authentication and robustness. Colleagues rely on him to translate subtle security edge-cases into reliable firmware and tooling improvements.
15 years of coding experience
21 years of employment as a software developer
it-gymnasiet
Stackoverflow
56reputation
1kreached
1answer
0questions
Github Skills (19)
it-security10
c1110
java10
security10
c1710
smartcard10
javas10
hidapi9
apidoc8
api8
mysql8
linux7
cryptography7
embedded6
php6
Programming languages (12)
Github contributions (5)
Yubico/libu2f-host
Sep 2014 - Sep 2020
Yubico Universal 2nd Factor (U2F) Host C Library
Role in this project:
Back-end & Security Engineer
Back-end & Security EngineerContributions:173 commits, 62 PRs, 120 pushes in 6 years 1 month
Contributions summary:Klas made significant contributions to the `libu2f-host` C library. They implemented changes to improve device handling, including handling dead devices and adding exponential timeouts for communication. Furthermore, they addressed security concerns by modifying the udev rules, whitelisting more PIDs, and integrating LGPL license headers. The user also refactored and improved code for authentication and registration processes.
hostc-libraryfactoryubicou2f
Yubico/yubico-pam
Jun 2012 - May 2022
Yubico Pluggable Authentication Module (PAM)
Role in this project:Back-end Developer
Back-end DeveloperContributions:24 reviews, 343 commits, 52 PRs in 10 years
Contributions summary:Klas primarily focused on improving the Yubico PAM module. Their contributions include refactoring code, fixing warnings, and enhancing the challenge-response functionality. They refactored the challenge-response logic to utilize the ykpers library and implemented checks to ensure different challenges receive different responses, addressing potential firmware bugs. Furthermore, the user implemented features like the -i switch for iteration counts and updated the documentation.
pamyubikeyauthenticationpluggable-authenticationyubico
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