Collected research

A Messy State of the Union: Taming the Composite State Machines of TLS

Benjamin Beurdouche, Karthikeyan Bhargavan, Antoine Delignat-Lavaud, Cédric Fournet, Markulf Kohlweiss, Alfredo Pironti, Pierre-Yves Strub and Jean Karim Zinzindohoue · ieee-security.org

Systematic testing of mainstream TLS stacks shows their composite state machines accept message sequences no valid handshake produces, because per-ciphersuite machines were merged carelessly. A network attacker can skip handshake messages to impersonate a server, or force export-grade RSA and factor the key (FREAK), breaking authentication; the paper adds a verified OpenSSL state machine.

Record

Researcher

Benjamin Beurdouche, Karthikeyan Bhargavan, Antoine Delignat-Lavaud, Cédric Fournet, Markulf Kohlweiss, Alfredo Pironti, Pierre-Yves Strub and Jean Karim Zinzindohoue

Published by

ieee-security.org

Format

Whitepaper

Topic

Crypto

In the archive

• Collected in the 2015 research round

Related sources

• A Messy State of the Union: Taming the Composite State Machines of TLS

Tags

• tls
• auth-bypass
• formal-analysis
• fuzzing
• https
• dynamic-analysis
• owasp-a01-2021
• owasp-a02-2021

This page is the archive's own catalogue record. The research is the work of Benjamin Beurdouche, Karthikeyan Bhargavan, Antoine Delignat-Lavaud, Cédric Fournet, Markulf Kohlweiss, Alfredo Pironti, Pierre-Yves Strub and Jean Karim Zinzindohoue, first published at the original source. Preserved copies are kept so the citation survives its host; this one was last captured on 14 August 2026.