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Chapter and Conference Paper
Chosen-Ciphertext Secure Dual-Receiver Encryption in the Standard Model Based on Post-quantum Assumptions
Dual-receiver encryption (DRE) is a special form of public key encryption (PKE) that allows a sender to encrypt a message for two recipients. Without further properties, the difference between DRE and PKE is o...
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Chapter and Conference Paper
Hidden \(\varDelta \) -Fairness: A Novel Notion for Fair Secure Two-Party Computation
Secure two-party computation allows two mutually distrusting parties to compute a joint function over their inputs, guaranteeing properties such as input privacy or correctness. For many tasks, such as joint comp...
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Chapter and Conference Paper
On the Correlation Complexity of MPC with Cheater Identification
Composable protocols for Multi-Party Computation that provide security with Identifiable Abort against a dishonest majority require some form of setup, e.g. correlated randomness among the parties. While this ...
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Chapter and Conference Paper
Sender-binding Key Encapsulation
Secure communication is gained by combining encryption with authentication. In real-world applications encryption commonly takes the form of KEM-DEM hybrid encryption, which is combined with ideal authenticati...
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Chapter and Conference Paper
Composable Long-Term Security with Rewinding
We circumvent these impossibility results with new techniques, enabling rewinding-based simulation in a way that universal composability is achieved. This allows us to construct a long-term-secure composable c...
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Chapter and Conference Paper
Universally Composable Auditable Surveillance
User privacy is becoming increasingly important in our digital society. Yet, many applications face legal requirements or regulations that prohibit unconditional anonymity guarantees, e.g., in electronic payme...
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Chapter and Conference Paper
Practically Efficient Private Set Intersection from Trusted Hardware with Side-Channels
Private set intersection (PSI) is one of the most important privacy-enhancing technologies with applications such as malware and spam detection, recognition of child pornography, contact discovery, or, more re...
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Chapter and Conference Paper
A New Security Notion for PKC in the Standard Model: Weaker, Simpler, and Still Realizing Secure Channels
Encryption satisfying CCA2 security is commonly known to be unnecessarily strong for realizing secure channels. Moreover, CCA2 constructions in the standard model are far from being competitive practical alter...
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Chapter and Conference Paper
ConTra Corona: Contact Tracing against the Coronavirus by Bridging the Centralized–Decentralized Divide for Stronger Privacy
Contact tracing is among the most important interventions to mitigate the spread of any pandemic, usually in the form of manual contact tracing. Smartphone-facilitated digital contact tracing may help to increase...
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Chapter and Conference Paper
Environmentally Friendly Composable Multi-party Computation in the Plain Model from Standard (Timed) Assumptions
Starting with the work of Rivest et al. in 1996, timed assumptions have found many applications in cryptography, building e.g. the foundation of the blockchain technology. They also have been used in the conte...
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Chapter and Conference Paper
Your Money or Your Life—Modeling and Analyzing the Security of Electronic Payment in the UC Framework
EMV, also known as Chip and PIN, is the world-wide standard for card-based electronic payment. Its security wavers: over the past years, researchers have demonstrated various practical attacks, ranging from u...
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Article
Open AccessOn the (Im-)Possibility of Extending Coin Toss
We consider the task of extending a given coin toss. By this, we mean the two-party task of using a single instance of a given coin toss protocol in order to interactively generate more random coins. A bit more f...
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Article
Karlsruher Thesen zur Digitalen Souveränität Europas
Die Digitale Souveränität stellt die Wirtschaft, Politik und Forschung Europas vor große Herausforderungen. Diese und mögliche Lösungen stellen führende Forscher im Bereich IT-Sicherheit der Karlsruher Forschu...
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Article
Sicherheit auf festem Fundament
Möchte man sichere IT-Systeme konstruieren, so kann man sich nicht auf Software alleine verlassen. Vertrauenswürdige Hardware ist ein unverzichtbarer Vertrauensanker für sichere IT-Lösungen, wie in diesem Beit...
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Chapter and Conference Paper
Reusing Tamper-Proof Hardware in UC-Secure Protocols
Universally composable protocols provide security even in highly complex environments like the Internet. Without setup assumptions, however, UC-secure realizations of cryptographic tasks are impossible. Tamper...
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Chapter and Conference Paper
Non-malleability vs. CCA-Security: The Case of Commitments
In this work, we settle the relations among a variety of security notions related to non-malleability and CCA-security that have been proposed for commitment schemes in the literature. Interestingly, all our s...
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Article
Cybersicherheit in den Biowissenschaften – Was können wir tun?
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Article
Sicherheit relativ definieren
In der modernen Kryptographie wird „Sicherheit“ mathematisch definiert. Einer der etablierten Ansätze, Sicherheit zu definieren, ist die „Simulationsbasierte Sicherheit“, bei der Sicherheit keine absolute Größ...
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Chapter and Conference Paper
A Novel Cryptographic Framework for Cloud File Systems and CryFS, a Provably-Secure Construction
Using the cloud to store data offers many advantages for businesses and individuals alike. The cloud storage provider, however, has to be trusted not to inspect or even modify the data they are entrusted with....
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Chapter and Conference Paper
Towards Realising Oblivious Voting
Electronic voting machines promise to determine election results more efficiently without sacrificing reliability. Two desirable security properties seem to contradict each other however: First, the voter’s ch...
