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[Master] Feasibility of Mix Networks for Instant Messaging

End to End encryption protects message contents, but communication metadata can (and is) still be used to identify the communicating parties. Mix networks unlink sender and receiver using layered encryption and delaying messages. This thesis analyzes whether the delays introduced can still cover today's low-latency Instant Messaging use cases.

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Discontinuation of GitLab Service at on 2020-04-31

Our GitLab Service at will be discontinued on 2020-04-31.

Don't Panic. will be operated as a normal, production-quality service until at least 2020-04-15, including regular updates and nightly backups. We will try to keep your data available and exportable until 2020-04-30.

Read on for the full announcement...

[Master] Ransomware Detection

Ransomware attacks – in contrast to other cyber attacks – must not be detected and especially not blocked or recovered on first sight. This relaxation is supported by the rareness of ransomware attacks. Certainly, the uprising of ransomware families, which are able to circumvent the detection mechanism, integrated into the local machine, prevents the approaches from taking advantage of the relaxation. Justified by the attack isolation, the move to the personal cloud storage is the reasonable way…

Secure and Private Collaboration through DNS

The mDNS-SD Privacy Extension replaces many multicast packets by unicast packets sent to pre-paired devices only, thus not only distributing less privacy-sensitive data in the network, but also reducing the amount of broadcast traffic that uses a considerable amount of resources on modern wireless networks.

[Master] Design and Analysis of a secure multi-party communication protocol

In the past years digital communication became an important aspect in every day life. Everything is shared and discussed in groups of friends, family or business part- ners without a proper way to protect that information. This master thesis introduces the first secure robust multi-party communication protocol which mimics a physical conversation with the help of a Diffie-Hellman key tree and social behaviours. Robust- ness against offline group members is reached by taking advantage of…

Securing Legacy Applications

TLS Interposter allows current SSL vulnerabilities to be fixed in legacy software that cannot be configured properly by replacing unsafe SSL parameters before any call to the SSL library is made.

SARA: Software Archiving of Research Artefacts

The SARA project (Software Archiving of Research Artefacts) aims to develop a new scientific service that allows long-term access and publishing of research data and scientific software. Its main focus is on software tools that support the processing and analysis of research data. In biological research, for example, measured data is collected and processed with the support of computers. Within Computer Science and Electrical Engineering, the different versions of newly developed software need…


Chat — instant messaging, audio and video calls — have come to form an integral part of our daily life. Most people use closed systems for these needs, which is acceptable for private use, but fail the privacy requirements for official use in a research or teaching environment. However, this does not have to be the case: WISEchat offers the security, comfort and availability demanded by a modern university based on the open, federated Extensible Messaging and Presence Protocols (XMPP).


[Bachelor] Mapping different datatypes ensuring secure cloud storage

In this thesis two generic approaches on how to store different datatypes to a cloud storage are proposed, thereby utilizing Treetank. As part of this thesis implementations for the proposed approaches have been implemented to evaluate their practicability and search out strengths as well as weaknesses. Current cloud storage systems, security concerns towards privacy, stability and integrity of data shared with “the Cloud” is discussed. An overview of Treetank, that originally was designed to be…

[Bachelor] A platform-independent iSCSI Target in Java

This Bachelor thesis describes the architecture of an iSCSI target written in Java, investigates the effects of various parameters on the program's performance, and compares the results to those of a native code implementation.