I am a researcher specializing in cryptography and its connections to IT security, verification and complexity theory. Specifically, I am fascinated by foundational questions such as building one-way functions from NP-hardness and understanding the conceptual implications of indistinguishability obfuscation. I aim to build foundations for analyzing and building cryptography that is used in the wild such as TLS, EMV, IEEE 802.11 and secure messaging protocols and white-box cryptography. White-box cryptography implements cryptography in insecure environments and is a mechanism required by Master and Visa to secure payment apps. TLS is the main protocol for secure communication on the internet (the s in https indicates that TLS is used), EMV is a secure communication protocol used for payment with MasterCard, VISA and Maestro, IEEE 802.11 is used, e.g., for secure communication in Eduroam, and secure messaging is nowadays deployed by most popular messaging apps. For protocol analysis, we use verification techniques and modularity to be able to tackle the complexity of the protocols. More generally, I am interested in modeling the security of a cryptographic object, i.e., ask the question "What does it mean to be secure?" and to answer that question by a mathematical model (while always being aware that gaps between models and reality necessarily have to exist) that is simple enough to understand the security guarantees conceptually.