News
Next Seminar on 10.04.2024
Written on 06.04.2024 19:20 by Mang Zhao
Dear All,
The next seminar(s) take place on 10.04.2024 at 14:00 (Session A) and 14:00 (Session B).
Session A: (14:00-15:30)
Julian Maurer, Marvin Schank, Matthias Michels
https://cispa-de.zoom.us/j/96786205841?pwd=M3FOQ3dSczRabDNLb3F1czVXVUpvdz09
Meeting-ID: 967 8620 5841
Kenncode: BT!u5=
Session B: (14:00-15:30)
Faiq Iftikhar Awan, Christian Bryan Marcelino, Tobias Berdin
https://cispa-de.zoom-x.de/j/66136901453?pwd=YVBSZU9peUpvUlk4bWp3MDR4cGlUUT09
Session A:
14:00 - 14:30
Speaker: Julian Maurer
No information is provided.
14:30 - 15:00
Speaker: Marvin Schank
Type of talk: Master Final
Advisor: Prof. Dr. Cas Cremers
Title: Formal Analysis of Matrix's End-to-End Encryption
Research Area: RA2: Reliable Security Guarantees
Abstract: Matrix is a federated, decentralised communication architecture that allows messenger applications like Element to provide end-to-end encrypted communication to its users. Researchers recently discovered practically exploitable vulnerabilities in Matrix, questioning its security. To tackle the uncertainty of whether Matrix is secure, one must look closely at Matrix's End-To-End-Encryption protocol. I want to show with a formal analysis of the protocol that Matrix can provide a frame for secure message transmission. In this thesis, I investigate Matrix's underlying encryption techniques, especially Short Authentication String, Olm, and Megolm, the main cryptographic subroutines. I rewrite those concepts into a symbolic model. Based on that model, Tamarin, a state-of-the-art model checker and security verification tool, conducts an analysis. I proved some of Matrix's central security guarantees, like message confidentiality and user authentication.
15:00 - 15:30
Speaker: Matthias Michels
Type of talk: Master Final Talk
Advisor: Christine Utz, Ben Stock
Title: Privacy, Anyone? Investigating the Adoption of Privacy-Friendly Services and Configurations
Research Area: RA5: Empirical and Behavioural Security
Abstract:
Many website embed third-party services, for example, to gain insights into their audience or for embedding additional content. They offer a quick way to integrate these functionalities, often at no extra cost for the website owner. Website owners can influence the amount of personal data processed by third-party services in two ways: Through their selection and if possible, through their configuration.
These choices must be made according to data protection law requirements. The GDPR, for example, requires website operators to limit the data collection to the minimum amount necessary and imposes requirements for data transfer to non-EU countries. To account for this, courts already have placed boundaries for configurations that must or must not be made. Such court decisions have already led to waves of cease-and-desist letters in Germany and Austria.
We conduct a web measurement on 100,000 websites to compare their usage of these configuration options, as well as two privacy-friendly services. For a sample of websites using a privacy-friendly configuration, we use the Internet Archive to un- derstand the temporal context of the adoption of the privacy-friendly configuration. We show that the usage of privacy-friendly services and configurations differs heavily between countries, even among those with similar data protection laws. We also show that websites typically adopt the privacy-friendly option of a third-party service upon its initial integration, or not at all.
Session B:
14:00 - 14:30
Speaker: Faiq Iftikhar Awan
Type of talk: Master Intro
Advisor: Prof. Dr. Andreas Zeller & Marius Smytzek
Title: More Tests, Better Repair?
Research Area: RA3
Abstract: An automated program repair is a tool that can automatically look for bugs in a program and fixes it using techniques like fault-localization, maximum branch coverage etc. Furthermore, test generation uses fuzzers to randomly generate test cases that increase branch coverage of a test subject. Fuzzers are software tools that can generate a large volume of random or semi- random data that can be directly fed into a test subject or program. With this definition in mind, we ask a question.
Does more tests translate to better repair?
We present a comprehensive analysis based on statistical data and results that tries to answer this question. Our approach utilizes recently published tools such as Avicenna, ISLa and Tests4Py to answer this simple question analytically. These tools serve as building blocks for a solution that can use minimal amount of tests to create a specification about a program. Then generate new test cases according to that specification and repair a program using test cases that provide most amount of coverage. Such repairs are then compared against a baseline. What level of enhancement, if any, does an increase in test cases contribute to the effectiveness of a program repair solution?
14:30 - 15:00
Speaker: Christian Bryan Marcelino
Type of talk: Bachelor Intro
Advisor: Stella Wohnig, Prof. Nico Döttling
Title: Evaluating Range Proof to Improve McFly
Research Area: RA1: Trustworthy Information Processing
Abstract: McFly is a Time-lock Puzzle(TLP) primitive created with the help of a blockchain (Proof of Stake) finality layer. Usually, a TLP needs much computational power to solve. With the help of blockchain technology, McFly is not computationally wasteful, and we can decide exactly when the puzzle will be solved.
A slight shortcoming resides in constructing the McFly protocol: The message lies in the exponentiation. Therefore, McFly needs a range proof to ensure that the message lies within a specific range. The proof size of the McFly protocol exceeds the preferred value, so we want to consider finding another range proof.
In this thesis, we will explore the state-of-the-art range proof protocols to improve McFly's situation. This thesis aims to find another range proof that is smaller not only in size but also more efficient in proving and verifying time and incorporating it into the McFly protocol.
15:00 - 15:30
Speaker: Tobias Berdin
Type of talk: Master Intro
Advisor: Dr. Nico Döttling
Title: Laconic Private Set Intersection with Preprocessing
Research Area: 2
Abstract:
Private set intersection (PSI) is a cryptographic primitive that allows two or more parties, each holding a private set of elements, to compute the intersection of their sets in such a way that no information is revealed other than the elements of the intersection. In particular, we consider the setting where one party, called the server, holds a very large set and wants to compute the intersection with a client's smaller set. Recently a lot of research has been devoted to developing PSI protocols with low communication and computation costs. However, even the most efficient constructions only achieve computation complexities that are at least linear in the size of the larger set.
This thesis aims to develop a new construction for PSI protocols that operates in the laconic setting, i.e. it divides computations into a two-round scheme, where all communication is independent or sublinear in the size of the server's set. This setting is highly practical, as clients, unlike servers, usually should not perform resource-intensive computations. A preprocessing approach helps to perform heavy server computations in advance, so that results are available quickly when requested by the client. Our new PSI construction is based on oblivious key-value stores and Bloom filters, achieving sublinear communication and computation costs on both the client and the server side.