David Schwarzbeck
David Schwarzbeck
Computer Science Department
Programming Systems Group (Informatik 2)
Martensstr. 3
91058 Erlangen
Germany
- Phone number: +49 9131 85-28996
- Fax number: +49 9131 85-28809
- Email: david.schwarzbeck@fau.de
- Website: https://www.ps.tf.fau.de/en/mitarbeitende/schwarzbeck/
Student contact hour
Prearrange an appointment by email.
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Software Watermarking
(Own Funds)
Term: since 01.01.2016
URL: https://www2.cs.fau.de/research/SoftWater/Software watermarking means hiding selected features in code, in order to identify it or prove its authenticity. This is useful for fighting software piracy, but also for checking the correct distribution of open-source software (like for instance projects under the GNU license). The previously proposed methods assume that the watermark can be introduced at the time of software development, and require the understanding and input of the author for the embedding process. The goal of our research is the development of a watermarking framework that automates this process by introducing the watermark during the compilation phase into newly developed or even into legacy code. As a first approach we studied a method that is based on symbolic execution and function synthesis.
In 2018, two bachelor theses analyzed two methods of symbolic execution and function synthesis in order to determine the most appropriate one for our approach. In 2019, we investigated the idea to use concolic execution in the context of the LLVM compiler infrastructure in order to hide a watermark in an unused register. Using a modified register allocation, one register can be reserved for storing the watermark. In 2020, we extended the framework (now called LLWM) for automatically embedding software watermarks into source code (based on the LLVM compiler infrastructure) with further dynamic methods. The newly introduced methods rely on replacing/hiding jump targets and on call graph modifications. In 2021, we added other adapted, dynamic methods that have already been published, as well as a newly developed method to LLWM. The added methods are based, among other things, on the conversion of conditional constructs into semantically equivalent loops or on the integration of hash functions, that leave the functionality of the program unchanged but increase its resilience. Our newly developed method IR-Mark now not only specifically selects the functions in which the code generator avoids using a certain register. IR-Mark now adds some dynamic computation of fake values that makes use of this register to blurr what is going on. There is a publication on both LLWM and IR-Mark. In 2022, we added another adapted procedure to the LLWM framework. The method uses exception handling to hide the watermark. In 2023, we adapted more methods to expand the LLWM framework. These include embedding techniques based on principles of number theory and aliasing.In 2024, we developed three new watermarking techniques: Register Expansion, SemaCall, and SideData.
They construct hash-like arithmetics that generate a watermarking message from a secret key. The first two techniques have been published in the paper "Register Expansion and SemaCall: 2 Low-overhead Dynamic Watermarks Suitable for Automation in LLVM" in the proceedings of the CheckMATE'24 workshop in Salt Lake City. We wrote an extended version containing the SideData watermark, currently under peer review for the DTRAP journal.
Optimierungen in Übersetzern
Basic data
| Title | Optimierungen in Übersetzern |
|---|---|
| Short text | inf2-ue2 |
| Module frequency | nur im Sommersemester |
| Semester hours per week | 2 |
Voraussetzung zur Teilnahme an der Prüfung ist die erfolgreiche Bearbeitung der Übungsaufgaben.
Parallel groups / dates
As a main focus the lecture gives an overview of optimizing techniques applicable to procedural programming languages. In particular, optimization techniques that are of importance to high performance computers and parallel computers are covered. Techniques and representations are introduced that are necessary to compute and to manage information required for optimization are covered as well.
The following list of key words provides an overview of the topics covered in this lecture:
- dependence analysis, dependence graph, array subscript analysis, SSA, control flow Graph, dominators.
- loop transformations: strength reduction, induction variable elimination, loop-invariant code motion, loop unswitching.
- loop reordering: loop interchange, loop skewing, loop reversal, strip mining, loop tiling, loop distribution, loop fusion.
- loop restructuring: loop unrolling, loop coalescing, loop replacement (reduction), loop idiom recognition.
- memory access transformations: array padding, cache miss jamming, scalar expansion, array contraction.
- partial evaluation: constant propagation, constant folding, algebraic simplification, strength reduction.
- redundancies removal: unreachable-code elimination, useless-code elimination, dead-variable elimination, common-subexpression elimination.
- procedure call transformations: leaf procedure optimization, procedure inlining, procedure cloning, function memoization, tail recursion elimination.
- transformations for parallel machines: data decomposition, scalar privatization, array privatization, data partitioning and computation partitioning, guard introduction, message aggregation, message pipelining, prefetch and poststore, syncronization elimination.
- pointer analysis, alias analysis null
1. Parallelgruppe
| Semester hours per week | 2 |
|---|---|
| Teaching language | German |
| Responsible |
David Schwarzbeck Tobias Heineken Prof. Dr. Michael Philippsen |
| Date and Time | Start date - End date | Cancellation date | Lecturer(s) | Comment | Room |
|---|---|---|---|---|---|
| wöchentlich Wed, 08:15 - 09:45 | 23.04.2025 - 23.07.2025 |
|
11301.00.031 |
Übungen zu Optimierungen in Übersetzern
Basic data
| Title | Übungen zu Optimierungen in Übersetzern |
|---|---|
| Short text | inf2-ueb-uebersetzer |
| Module frequency | nur im Sommersemester |
| Semester hours per week | 2 |
Zeit und Ort für die Übungen werden in der ersten Vorlesungsstunde vereinbart.
Parallel groups / dates
In der Übung werden die in der Vorlesung vorgestellten Konzepte und Algorithmen zur Optimierung von Programmen durch einen Übersetzer wiederholt und vertieft.
Im Rahmen der Projektübungen erweitern die Übungsteilnehmer den in Übersetzerbau 1 implementierten Übersetzer um eine Auswahl der vorgestellten Algorithmen.
Die Materialien zur Lehrveranstaltung werden über StudOn bereitgestellt.
1. Parallelgruppe
| Semester hours per week | 2 |
|---|---|
| Teaching language | German |
| Responsible |
Tobias Heineken Prof. Dr. Michael Philippsen David Schwarzbeck |
| Date and Time | Start date - End date | Cancellation date | Lecturer(s) | Comment | Room |
|---|---|---|---|---|---|
| wöchentlich Tue, 12:15 - 13:45 | 22.04.2025 - 22.07.2025 | 10.06.2025 22.04.2025 |
|
11302.02.133 |
In der Übung werden die in der Vorlesung vorgestellten Konzepte und Algorithmen zur Optimierung von Programmen durch einen Übersetzer wiederholt und vertieft.
Im Rahmen der Projektübungen erweitern die Übungsteilnehmer den in Übersetzerbau 1 implementierten Übersetzer um eine Auswahl der vorgestellten Algorithmen.
Die Materialien zur Lehrveranstaltung werden über StudOn bereitgestellt.
2. Parallelgruppe
| Semester hours per week | 2 |
|---|---|
| Teaching language | German |
| Responsible |
David Schwarzbeck Tobias Heineken Prof. Dr. Michael Philippsen |
| Date and Time | Start date - End date | Cancellation date | Lecturer(s) | Comment | Room |
|---|---|---|---|---|---|
| wöchentlich Tue, 10:15 - 11:45 | 29.04.2025 - 22.07.2025 | 10.06.2025 |
|
11302.02.134 |
In der Übung werden die in der Vorlesung vorgestellten Konzepte und Algorithmen zur Optimierung von Programmen durch einen Übersetzer wiederholt und vertieft.
Im Rahmen der Projektübungen erweitern die Übungsteilnehmer den in Übersetzerbau 1 implementierten Übersetzer um eine Auswahl der vorgestellten Algorithmen.
Die Materialien zur Lehrveranstaltung werden über StudOn bereitgestellt.
3. Parallelgruppe
| Semester hours per week | 2 |
|---|---|
| Teaching language | German |
| Responsible |
David Schwarzbeck Prof. Dr. Michael Philippsen Tobias Heineken |
| Date and Time | Start date - End date | Cancellation date | Lecturer(s) | Comment | Room |
|---|---|---|---|---|---|
| wöchentlich Mon, 10:15 - 11:45 | 28.04.2025 - 21.07.2025 | 09.06.2025 |
|
11302.02.133 |
2024
- :
Erweiterung eines Rahmenprogramms für das automatische Einfügen von Software- Wasserzeichen in Quellcode (Master thesis, 2024)
URL: https://github.com/FAU-Inf2/LLWM/blob/main/semacall + register-expansion + sidedata/thesis-1.pdf
BibTeX: Download - , , :
Register Expansion and SemaCall: 2 Low-overhead Dynamic Watermarks Suitable for Automation in LLVM
ACM SIGSAC Conference on Computer and Communications Security (CCS'24), Workshop on Offensive and Defensive Techniques in the Context of Man At The End (MATE) attacks (Checkmate ’24) (Salt Lake City, UT, 18.10.2024 - 18.10.2024)
In: CheckMATE '24: Proceedings of the 2024 Research on offensive and defensive techniques in the context of Man At The End (MATE) attacks, New York: 2024
DOI: 10.1145/3689934.3690815
URL: https://dl.acm.org/doi/10.1145/3689934.3690815#
BibTeX: Download - , , , , :
Register Expansion and SemaCall: 2 low-overhead dynamic Watermarks suitable for Automation in LLVM [Source code and Raw Experiment data]
(2024)
DOI: 10.5281/zenodo.13337275
BibTeX: Download
(anderer)