Next Seminar on 05.07.2023

Written on 03.07.2023 09:34 by Niklas Medinger

Dear All,

The next seminar(s) take place on 05.07.2023 at 14:00 (Session A) and 14:00 (Session B).

Session A: (14:00-15:30)
Tim Scheckenbach, Louise Malvin Tanaka, Mikka

Meeting-ID: 967 8620 5841
Kenncode: BT!u5=


Session B: (14:00-15:30)

Robert Pietsch, Oliver Valta, Simon Anell


Session A:

14:00 - 14:30

Speaker: Tim Scheckenbach
Type of Talk: Bachelor Intro
Advisor: Prof. Dr. Andreas Zeller
Title: Specification-Based Fuzzing of x509 Certificates
Research Area: RA5
x509 certificates have been around for about 35 years to ensure secure web browsing
and identification. Because it is widely used, it must be secure, which can only
be achieved through extensive testing. However, this is a very difficult and costly
challenge due to the complexity of the x509 format. Automated testing techniques
such as fuzzing are needed to assist in this task.

In this talk, I will introduce the basic concepts of x509 certificates and specification-based fuzzing.
Moreover I will introduce the approach I take in my thesis, by building a fuzzer upon the ISLa solver, a
grammar-aware constraint solver. Using a grammar and some constraints the fuzzer is able to generate valid
certificates from scratch covering most of the different formats the x509 standard offers.

14:30 - 15:00

Speaker: Louise Malvin Tanaka
Type of Talk: Bachelor Intro
Advisor: Dr. Lucjan Hanzlik
Title: Implementation of Virtual ePassport Based on ICAO MRTD
Research Area: RA1: Trustworthy Information Processing
Online verification, such as age verification nowadays lacks common standard that could be used across the internet.
On lower security level, some sites just trust what user inputs without any further verification.
On some heavier cases, verification process require user's personal identity (ex. ID card) and it takes some time to process.

To solve this problem, there exists some solution by creating a virtual ID that could be used to verify a user identity
accross the internet. However, instead of creating a new infrastructure, could we use existing one that are already widely available nowadays to solve this? By utilizing electronic passport, we could skip the bootstrap process to create a virtual ID, since it
has already done by the government. Extending functionality of epassport to be used to verify ourself on the internet would be the goal of this talk.

15:00 - 15:30

Speaker: Mikka Rainer
Type of Talk: Bachelor Intro
Advisor: Michael Schwarz, Lukas Gerlach
Title: Reversing the Microarchitecture with Microkernels
Research Area: RA3

The microarchitecture of modern CPUs contains many undocumented hash functions that distribute data to other microarchitectural elements. With knowledge of these hash functions, an attacker can significantly improve existing attacks or make new attacks against the microarchitecture possible. Due to that, these functions are important to create novel defenses and mitigations. While several of these hash functions have been successfully reversed, many functions on newer CPUs are still unknown. Existing techniques fail to reverse them, as the process of reversing the function relies on noise-free measurements.

In this thesis, we investigate how we can create a noise-free measurement environment for microarchitectural reversing by leveraging the power of microkernels. , we show how we can significantly improve the measurements in comparison to previous techniques, at the example of the addressing function of last-level cache slices.


Session B:

14:00 - 14:30

Speaker: Robert J. Pietsch
Type of talk: Bachelor Intro
Advisor: Dr. Michael Schwarz, Lukas Gerlach
Title: Automated Checking of C Compiler Optimization Effects on Data Obliviousness
Research Area: RA3

Being close to the limit of what is physically possible, the performance of modern general-purpose processors is no longer significantly increased by packing more transistors onto the dye or increasing the clock frequency. Instead, CPU manufacturers employ sophisticated optimizations like caches, branch predictors, and dynamic code reordering. While these optimizations provide a performance advantage in many real-world applications, they come at a heavy security cost: Plenty of microarchitectural side-channel attacks have been discovered that abuse optimizations to leak secret data. Examples are timing attacks on caches that allow attackers to detect locations of previous memory accesses and infer secret data.

One solution to this is writing programs in a "data-oblivious" way (also known as "constant-time programming"), not to perform any secret-dependent memory accesses. Data-obliviousness is a property of assembly code where only a few highly-specialized compilers can give guarantees dependent on the C code. When using other compilers (e.g. gcc or clang), it is currently impossible to derive such guarantees from a given C code. Especially for more complex compilers, formal verification is not feasible due to the complexity introduced by numerous optimizations and combinations thereof.

In this work, we present a tool to automate testing the behavior of several compilers on fixed C code snippets concerning data-obliviousness with different optimization combinations enabled. We employ the tool to check C constructs that, by the current research state, are recommended for developing data-oblivious programs. To trigger more sophisticated optimizations, we also fuzz-generate C code that we expect to be compiled into data-oblivious code and again analyze the compiler behavior with our tool. Additionally, we use the tool to analyze several cryptographic implementations for data-obliviousness violations when compiled with specific optimizations enabled.

14:30 - 15:00

Speaker: Oliver Valta
Type of talk: Bachelor Intro.
Advisor: Lucjan Hanzlik
Title: Practical One-time Programs and Applications to eCash
Research Area: Algorithmic foundations and cryptography

Digital money is an irreplaceable part of our society. However, most existing systems for eCash only work online. Despite benefits such as availability and privacy, offline transaction systems are still uncommon. For such systems, preventing double-spending typically relies on hardware.
One-time programs (OTP) allow computations on a single input without leaking anything about the program. OTPs can be used to reduce the complexity of the required hardware for offline transactions by relying on one-time memory devices.

In this thesis, we employ one-time programs to construct an eCash system and prove its security. We explore offline transactions as well as their limitations, and discuss the privacy of this system, both between users and the central instance.
Furthermore, we show how this system can be realized using existing hardware and the Android Keystore system.

15:00 - 15:30

Speaker: Simon Anell

No information provided.


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