Franziskus Kiefer
Co-Founder & CEO at Cryspen
Berlin, Germany
Summary
🤩
Rockstar🎓
Top SchoolFranziskus Kiefer is a Berlin-based security and cryptography engineer, researcher, and serial founder with 13 years of experience building high-assurance cryptographic systems and teams. As Co-Founder & CEO of Cryspen (and founder of CryptoEng), he helps organizations define and achieve provable levels of trust in software, drawing on prior leadership of security engineering at Wire and crypto research at Fraunhofer AISEC. He has hands-on experience bringing formally verified primitives into production—contributions that span NSS, HACL*, RustCrypto codecs, and Bouncy Castle—combining protocol design, vetted implementations, and secure engineering practices. Notably, he led deployment of end-to-end encrypted group video calls and implemented an open-source MLS library in Rust, showing a rare mix of protocol research and product-grade delivery. Educated to PhD level, he balances academic rigor with startup execution and a track record of adapting formally verified crypto for real-world stacks.
13 years of coding experience
10 years of employment as a software developer
Technischen Universität DarmstadtDoctor of Philosophy (PhD) Computer Science, Doctor of Philosophy (PhD) Computer Science at University of Surrey
English, German
Github Skills (26)
crypto10
data-serialization10
c1110
java10
security10
c1710
serialization10
javas10
deserialization10
nss10
asn110
cryptography10
curve10
generics10
rust10
Programming languages (23)
Github contributions (5)
RustCrypto/formats
Oct 2021 - Jan 2023
Cryptography-related format encoders/decoders: DER, PEM, PKCS, PKIX
Role in this project:
Back-end Developer
Back-end DeveloperContributions:81 reviews, 19 commits, 82 PRs in 1 year 3 months
Contributions summary:Franziskus primarily contributed to the `tls-codec` library, focusing on implementing and improving various codecs and traits for cryptographic format encoders/decoders. Their work included implementing traits for borrowed primitives, adding support for variable-length vectors (QUIC-style), fixing bugs related to empty vectors, and enhancing the serialization and deserialization capabilities for different data structures within the library. The user also implemented derive macros for TLS serialization and deserialization and improved the generics used by the library.
cryptographyderpemencoderspkcs
hacl-star/hacl-star
Sep 2017 - Jan 2023
HACL*, a formally verified cryptographic library written in F*
Role in this project:Back-end Developer / Security Engineer
Back-end Developer / Security EngineerContributions:102 reviews, 151 commits, 64 PRs in 5 years 4 months
Contributions summary:Franziskus contributed to the HACL\* cryptographic library by integrating and patching NSS (Network Security Services) files, specifically involving Curve25519 implementations. Their work included modifying C header and source files for integration with NSS, updating build scripts, and addressing code comments. The user's contributions focused on adapting and patching the cryptographic primitives to be compatible with a specific environment or library, demonstrating security-related engineering skills.
inriacoq-librarycryptographicformal-verificationverified
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