Research:

My main research interest are multivariate equations over finite fields. They can be used both for public key cryptography (e.g., HFE) and also for attacking existing stream and block ciphers (MQ attack). However, they are a rather new research topic, e.g., the question is still open, if the MQ attack really works. In addition, I developed a Zero-Knowledge protocol based on multivariate quadratic equation.

Finally, I work on normality of Boolean functions and developed an algorithm which checks for a Boolean function if it is normal or not. This is joint work with An Braeken.

2003: Developing a Zero-Knowledge scheme based on multivariate quadratic equations, developing and implementing an algorithm for checking the normality of Boolean functions, working on the security of unbalanced oil and vinegar (UOV) schemes, and working on Groebner bases.

2004: Improving the normality-algorithm from 2003, continuing the work on the security of UOV, and breaking the RS(S)E(2)PKC system from Kasahara and Sakai. In addition, I reviewed the security of the Hidden Field Equations (HFE), and the algorithmical problem of computing their public key, and found some equivalence classes for multivariate quadratic schemes.

2005: Continuing the work on equivalent private keys for multivariate schemes, studying differential attacks against multivariate schemes, and working on a taxonomy of all multivariate schemes known so far.

Biography:

• Born in 1977 in Bobingen (County Augsburg, Bavaria, Germany).
• 1996 - 2002: computer science at the University of Ulm (Germany) with minor philosophy.
• 2001-2002: year abroad of 13 month at the University College Cork (Ireland).
• 2002: Graduation as "Diplom Informatiker" (Dipl.-Inf.) - would translate to an MSc in Computer Science in other countries.
• 2003-Nov. 2005: PhD student at COSIC.
• since Dec. 2005: Post-Doc at the Ecole Normale Superieur, Paris (France)

Editorship:

• Organizer of the bi-annual German workshop "Kryptotag".

Membership:

• Member of the Board of the German special interest group of applied cryptography.