Stealthy Kleptographic Cryptosystems

Degree: Master
Contact Person:Thomas Eisenbarth

Field of Research

Kleptography describes the idea of putting secure back doors into black box cryptographic modules in a secure manner. That means, a party B can create a back door in the cryptosystem used by A in such a way that the backdoor can only be used by B. Furthermore, the party also can remain uncaught even if the backdoor is found and outputs of the backdoored cryptosystem are indistinguishable from regular outputs, except for B.

The idea of Kleptography was proposed more than 20 years age. However, as a result to the Snowden revelations, the topic is of renewed interest. New algorithm substitution attacks (ASA) now allow the extension of kleptographic methods to all types of cryptography, including common public key and symmetric schemes.

Project Scope

The goal of this project is to explore the practical side of modern kleptographic systems: Their applicability to commonly used crypto standards should be explored. A strong focus is on the stealthyness and performance of found solutions. How much do such systems differ in performance and other obvious system features such as code size from the non-backdoored counterparts? How efficient is the information leakage for the different cryptosystems?

Why me?

Working on this project can provide the opportunity to

  • Develop a deeper understanding of advanced cryptographic functionality and services
  • Gain practical experience in designing and implementing cryptographic systems
  • Contribute to the public understanding of the severity of threats through powerful persistent adversaries to our common security infrastructure.